This paper examines the financial transformation of Inter Miami CF after the arrival of Lionel Messi in July 2023 through the lens of #cognitive_economics rather than conventional sport finance. Standard explanations of the club's rise treat the outcome as a talent story: a great player joined a weak team, results improved, and money followed. This paper argues that such an account is incomplete. The scale and speed of the club's revaluation, from an estimated pre Messi value of 585 million United States dollars to a reported 1.45 billion dollars within roughly two and a half years, cannot be explained by athletic output alone, because the commercial gains arrived faster than the sporting ones. Instead, this study proposes a two stage psychological mechanism. In the first stage, the #frequency_illusion, popularly known as the #Red_Car_Effect or the Baader Meinhof phenomenon, converted a modest franchise into an object of constant #selective_attention. Strategic #visual_branding, anchored by a distinctive pink shirt, celebrity attendance, and a global streaming distribution deal, ensured that once consumers registered the club, they began to see it everywhere. In the second stage, the #halo_effect governed interpretation. Because Messi carries an almost unchallenged reputation for on field genius, sponsors, investors, broadcasters, and casual fans transferred that single positive judgment onto the entire organisation, its stadium, its ownership, its management, and its league. Using a qualitative, theory building case study design based on published financial estimates, peer reviewed research on #superstar_economics, and documented commercial events, the paper develops a Notice Then Judge model of value creation. The findings suggest that the true #Messi_Effect is less a story about football and more a demonstration of how #cognitive_bias can be organised, marketed, and monetised. The paper closes by discussing the fragility of halo driven valuations, the #key_person_risk that follows from them, and the ethical questions raised when firms deliberately engineer bias in consumer judgment. Keywords: cognitive economics, frequency illusion, halo effect, superstar effect, brand equity, sport finance, Major League Soccer, behavioural economics 1. Introduction 1.1 The Problem With Talent Based Explanations When a sports franchise triples in value in less than three years, the standard explanation is performance. Better players produce better results, better results attract more fans, more fans generate more revenue, and higher revenue supports a higher valuation. This chain of reasoning is intuitive and it is often correct. It is also, in the case of Inter Miami CF, insufficient. Consider the sequence of events. Lionel Messi agreed to join #Inter_Miami in June 2023 and made his debut in July of that year. At the moment of the announcement, Inter Miami sat at the bottom of the Eastern Conference of #Major_League_Soccer. It had never won a trophy. It had a small stadium in Fort Lauderdale rather than a marquee venue in Miami itself. It had a short and undistinguished history, having entered the league only in 2020. Yet the commercial revaluation did not wait for the sporting turnaround. Secondary market ticket prices for the club's home matches began climbing within days of the announcement, long before Messi had kicked a ball in the league. Merchandise sold out before it could be worn. Sponsors began negotiating before a single competitive match had been played. This ordering matters enormously for theory. If commercial value had followed sporting achievement, the club would be an ordinary case of investment and return. Instead, commercial value preceded sporting achievement. Something was being priced that was not yet on the field. That something, this paper argues, was a change in #consumer_perception, and more precisely a change in two distinct cognitive processes: what people noticed, and how people judged what they noticed. 1.2 The Argument in Brief The argument of this paper is that Inter Miami's revaluation was produced by a two stage mechanism, and that the two stages are psychologically separate, sequential, and mutually reinforcing. The first stage is attentional. Human beings cannot process the enormous volume of information that reaches their senses. They filter. Once an item is flagged as personally relevant, the filter changes and the item appears to be everywhere, even though its objective frequency in the environment has not changed. Psychologists call this the frequency illusion. In consumer terms, it is the reason someone who has just bought a red car suddenly sees red cars on every street. Inter Miami, through a deliberately unusual pink shirt, an aggressive celebrity strategy, and a global streaming platform, engineered exactly this condition on a planetary scale. The club became impossible not to notice. The second stage is evaluative. Once attention is captured, the mind must make a judgment, usually with far less information than the judgment deserves. Under such conditions people rely on a single salient trait and extend it outward. This is the halo effect, first documented more than a century ago and repeatedly confirmed since. Messi's salient trait, his footballing excellence, is close to universally accepted. That single trait was extended to the club that employs him. A franchise with no trophies and a temporary stadium was suddenly perceived as a premium, world class sporting institution, because the mind does not easily separate a great player from the organisation that surrounds him. This is #cognitive_spillover: the transfer of an evaluation from one object to an adjacent object with which it shares no necessary connection. The two stages are not interchangeable. Attention without a favourable evaluation produces notoriety, not value. Evaluation without attention produces a good product nobody sees. Value at scale requires both, in that order. The paper therefore proposes a Notice Then Judge model, in which the frequency illusion supplies volume of attention and the halo effect supplies direction of judgment. 1.3 Why This Matters Beyond Football The case has significance well outside sport. Modern markets are increasingly attention constrained rather than supply constrained. In such markets, the scarce resource is not production capacity but a place in the consumer's field of notice. If the two stage mechanism described here is generalisable, then any firm that can manufacture salience and then attach it to a credible positive signal can, in principle, achieve rapid revaluation without a corresponding change in underlying operational quality. That prospect is commercially attractive and ethically uncomfortable in equal measure. It is one of the central concerns of #behavioral_economics that the same insights which explain consumer welfare can also be used to reduce it. 1.4 Research Questions This study addresses four questions. What specific design choices by Inter Miami and Major League Soccer created the conditions for the frequency illusion at global scale? Through what channels did the halo surrounding Lionel Messi transfer to the club as an economic entity? Can the observed financial outcomes, including valuation, ticket prices, attendance, and sponsorship, be explained more completely by a cognitive model than by a talent model? What are the boundary conditions, risks, and ethical limits of a valuation built on engineered bias? 1.5 Structure of the Paper Section 2 reviews the relevant literature across three streams: superstar economics, attention and the frequency illusion, and the halo effect in consumer and organisational judgment. Section 3 develops the conceptual framework and states four propositions. Section 4 explains the methodology and its limits. Section 5 describes the pre Messi baseline. Sections 6 and 7 present the evidence for stage one and stage two respectively. Section 8 assembles the financial record. Section 9 discusses the fragility of halo based value, including #succession_risk. Section 10 sets out theoretical and managerial contributions. Section 11 addresses limitations and future research. Section 12 concludes. 2. Literature Review 2.1 The Economics of Superstars The economic study of exceptional individuals begins with the observation that in certain markets, small differences in talent produce enormous differences in reward. Rosen (1981) argued that this happens where a performer's output can be reproduced at low marginal cost and where consumers prefer a small amount of the best over a large amount of the merely good. Nobody wants ten average violinists instead of one great one. Broadcasting, streaming, and social media have intensified this logic, because the cost of distributing one more viewing of Messi is effectively zero. Later work distinguished talent based stardom from popularity based stardom. A performer may be rewarded not only because they are objectively better but because they are widely known, and being widely known is itself self reinforcing. Recent empirical work in sport economics has begun to separate these two effects. Jedelhauser, Flepp and Franck (2023) show that in European football the market systematically overvalues the most popular players relative to their measurable contribution, while undervaluing highly capable second tier players whose names are less familiar. The market, in other words, does not simply pay for output. It pays for #salience. The applied literature on the star effect in stadium demand is now substantial. Schreyer and Singleton (2025) examined the arrival of Cristiano Ronaldo in the Saudi Pro League and found that his presence raised home stadium attendance by roughly one fifth, raised attendance at the stadiums he visited by about fifteen percent, and produced a small positive effect even on matches in which he did not appear. This last result is the #superstar_externality: a star lifts the entire league, not only his own club. Stephenson (2024a, 2024b) found comparable patterns in American women's sport, showing that the arrival of Caitlin Clark generated attendance effects that spilled far beyond her own team, and that star participation shapes demand in the National Women's Soccer League. Gnagey and Koford (2026) extended this work with a long panel of Women's National Basketball Association games and concluded that Clark's attendance effect exceeded that of any prior player in the league's history. For Messi specifically, the most direct evidence comes from a 2025 study in the Journal of Sport Management, which used secondary market resale data rather than reported attendance. Reported attendance is a blunt instrument because stadiums have capacity ceilings; once a venue sells out, additional demand becomes invisible in the attendance figure. Resale prices have no ceiling. The study found that Messi's arrival raised resale prices for Inter Miami home matches by between roughly eleven and twelve times, and raised prices for the club's away matches by between four and five times, during the 2023 season. It also found a #spillover_effect on matches not involving Inter Miami at all, although this effect varied by club and was in some cases negative, consistent with a displacement of local spending toward the one fixture that mattered. These studies establish that the star effect is real and large. What they do not do, and do not claim to do, is explain the psychological pathway. They measure the outcome, not the mechanism. That is the gap this paper addresses. 2.2 Attention, Salience, and the Frequency Illusion The second literature stream concerns attention. The human perceptual system receives far more information than consciousness can handle, so it filters aggressively and pre consciously. What survives the filter is what has been marked as relevant. The frequency illusion, sometimes called the Baader Meinhof phenomenon, describes the experience that follows a change in this marking. The term was popularised by the linguist Arnold Zwicky in 2005 to describe the sensation of encountering a newly learned word everywhere immediately after learning it. The illusion has two components. The first is selective attention: once primed, the mind detects instances it previously filtered out. The second is #confirmation_bias: each detected instance is registered as evidence of a pattern, while the countless moments when the item was absent are not registered at all. A third mechanism, the #availability_heuristic, then converts the ease of recall into a judgment about real world frequency. Because instances come to mind easily, they feel common. Importantly, the illusion is not a perceptual error in the sense of seeing something that is not there. The red cars were always on the road. What changes is the observer's filter, not the world. This distinction is what makes the phenomenon commercially exploitable. A brand does not need to increase its actual presence in the environment as much as it needs to cross the threshold at which the consumer's filter begins to admit it. Experimental work supports the link between attention and preference rather than merely attention and awareness. Egger and Florack (2022) demonstrated that manipulating selective attention toward an object subsequently changed participants' preferences and choices regarding that object, and explored the mechanisms by which this occurs. This is the crucial bridge for the present paper. If attention only produced awareness, it would be commercially neutral. Because attention also shifts preference, it is commercially productive. Being noticed is not the same as being liked, but being noticed reliably makes being liked more probable. 2.3 The Halo Effect The halo effect was first documented by Thorndike (1920), who observed that military officers rating their subordinates produced correlations between unrelated traits that were implausibly high. An officer judged to be physically impressive was also judged to be intelligent, loyal, and capable of leadership. A single strong impression coloured every subsequent judgment. Nisbett and Wilson (1977) later showed that people are not merely subject to this bias, they are unaware of it, and will confidently deny it while displaying it. Contemporary reviews confirm that the effect is robust and appears across evaluation contexts, from education to recruitment to consumer choice (Noor et al., 2023). In marketing, the halo effect is the theoretical foundation of celebrity endorsement: the assumption is that the endorser's positive attributes will transfer to the endorsed product. Hariningsih, Haryanto, Wahyudi and Sugiarto (2025), in a decade spanning review of endorsement research, document how the field has expanded from traditional celebrities to influencers and virtual figures, while the underlying transfer logic has remained largely unchanged. The halo is not unconditional. Cui, van Esch, Eskridge, Ladlow and Northey (2025) analyse what they call the diminishing halo effect, showing that negative events involving a celebrity can reverse the transfer, with consumer attribution determining whether the damage attaches to the celebrity alone or spreads to the brand. Their work implies that a halo is an asset with a liability attached: whatever the celebrity's #reputation gives, it can also take away. Within sport specifically, evidence for halo distorted evaluation is direct and experimental. Pan, Pereira, Gomez Gonzalez and Dietl (2025) presented participants with football highlights and manipulated whether player identity was visible. When identities were shown, superstars received systematically higher ratings for the same actions. When identities were hidden, the premium fell sharply. Observers were not rating the play. They were rating the name attached to the play. Deutscher, Neuberg and Thiem (2023) find related shadow effects in tennis, where the presence of an acknowledged great alters how everyone else is perceived and evaluated. At the organisational level, Biegert, Kuehhirt and Van Lancker (2023) demonstrate cumulative #status_bias in National Basketball Association All Star selections, where prior recognition predicts future recognition independently of performance. This is the #Matthew_effect: to those who have, more is given. It is the halo effect extended across time, and it explains why status, once achieved, tends to persist even when the underlying performance does not justify it. 2.4 Noise, Judgment, and Organisational Valuation Kahneman, Sibony and Sunstein (2021) argue that professional judgment is not only biased but noisy, meaning that it varies unpredictably even among experts evaluating identical information. Franchise valuation is precisely such a judgment. It rests on multiples, comparables, projections, and assessments of brand strength, all of which are estimates rather than measurements. Where judgment is noisy and anchored on impressions, a strong salient signal can move the whole distribution. A valuation is not a fact discovered in the world. It is an opinion, formed by human beings, using #heuristics. This is the point at which the psychology literature and the finance literature meet, and it is a point that sport finance research has largely left unexplored. 2.5 The Gap Three gaps emerge from this review. First, the star effect literature measures outcomes without modelling the cognitive pathway that produces them. Second, the halo effect literature examines the transfer from person to product, but rarely the transfer from person to an entire firm, its ownership, its venue, and its league. Third, the frequency illusion is well described in cognitive psychology but has almost never been treated as a deliberate corporate strategy with measurable financial consequences. This paper addresses all three by treating Inter Miami as an integrated case in cognitive economics. 3. Conceptual Framework: The Notice Then Judge Model 3.1 Overview The proposed framework holds that rapid, outsized revaluation of a consumer facing enterprise requires two sequential cognitive conditions. Stage One: Notice. The enterprise must cross the attentional threshold of a mass audience. This is achieved not by increasing objective media volume alone but by supplying a distinctive perceptual marker that the mind can lock onto, together with a triggering event that makes the marker personally relevant. Once locked on, the audience experiences the frequency illusion and perceives the brand as ubiquitous. Stage Two: Judge. Having noticed, the audience must evaluate. Because evaluation occurs quickly and with limited information, it relies on the most salient available trait. If that trait is strongly positive and credibly attached to the enterprise, the halo effect extends it across all attributes of the enterprise, including those about which the audience knows nothing. The output of the two stages is a revised #perceived_quality, which then feeds directly into #willingness_to_pay for tickets, merchandise, sponsorship, broadcast access, and equity. 3.2 The Perceptual Anchor Stage one requires what this paper calls a perceptual anchor: a simple, unusual, high contrast visual signal that can be recognised instantly and at low cognitive cost. The anchor must be rare enough to avoid confusion with competitors and simple enough to survive compression into a thumbnail, a phone screen, or a passing glance. The #pink_jersey is an unusually effective anchor. Pink is rare in elite men's football, where most clubs use combinations of red, blue, white, and black. It is therefore uncontaminated by competing associations. It is recognisable at a distance, in low resolution, and out of context. A pink shirt in a crowd photograph, a music video, or a street scene is identifiable even when the badge is not readable. The anchor does the work of the brand without requiring the brand to be named. 3.3 The Triggering Event An anchor alone is inert. A pink shirt worn by a mid table club is simply a pink shirt. The anchor becomes active only when a triggering event makes it relevant. The Messi announcement was that event. It gave hundreds of millions of people a reason to encode the club, and encoding is what changes the filter. 3.4 Propositions Proposition 1. The combination of a distinctive perceptual anchor and a high salience triggering event produces perceived ubiquity that exceeds actual media volume, generating the frequency illusion at scale. Proposition 2. Once perceived ubiquity is established, evaluation of the enterprise will be dominated by the single most salient positive trait available, and that trait will be extended to unrelated organisational attributes. Proposition 3. Because cognitive revaluation is faster than operational change, financial indicators driven by perception, such as resale ticket prices, merchandise, sponsorship, and franchise valuation, will move earlier and more sharply than indicators driven by production, such as league standing, squad quality, and infrastructure. Proposition 4. Value created through cognitive transfer is contingent on the continued credibility and presence of the source of the halo, and is therefore structurally fragile. 4. Methodology 4.1 Design This study uses a single, instrumental, theory building #case_study. The design is appropriate where the aim is explanation of a mechanism rather than estimation of an average effect, where the phenomenon cannot be separated from its context, and where the case is extreme enough that the mechanism of interest is unusually visible. Inter Miami satisfies all three criteria. The study is explicitly qualitative and interpretive. It does not claim to establish causal identification in the econometric sense. Where causal estimates exist in the published literature, they are cited as supporting evidence rather than generated here. 4.2 Data The evidence base consists of three categories of #secondary_data. First, peer reviewed research on superstar effects, attention, and halo driven evaluation, as reviewed in Section 2. This provides the theoretical scaffolding and, in the case of the Journal of Sport Management study on Messi and resale prices, direct quantitative evidence about the case itself. Second, published financial estimates produced by established valuation firms in sport business media, principally the annual franchise valuations compiled by Sportico and Forbes, together with revenue estimates reported by those outlets. These figures are estimates, not audited statements, and are treated as such throughout. Third, the documented record of commercial and sporting events: the signing announcement of 2023, the Leagues Cup victory of the same year, the league championship secured in the 2025 season, the contract extension carrying Messi through the 2028 season, and the club's stadium development programme. 4.3 Analytical Procedure Analysis proceeded by #triangulation. Each proposition was tested against the three data categories, and retained only where the categories converged. Where they diverged, the divergence is reported rather than resolved in favour of the theory. Particular attention was paid to sequence, since the central claim of the paper is about ordering: perception moved before production. 4.4 Limitations of the Design Three limitations must be stated at the outset rather than buried in a later section. The first is attribution. Messi's arrival coincided with other developments, including a league wide streaming agreement, the approach of a World Cup hosted in North America, and rising franchise values across American professional sport generally. Isolating the Messi component from these trends is not possible with the design used here. The paper's response is to point to relative magnitude and to timing: no other MLS club recorded comparable growth in the same period, and the movement began at the moment of the announcement rather than at the moment of any sporting achievement. The second is measurement. Cognitive processes are inferred, not observed. This study has no experimental data on the mental states of Inter Miami's consumers. It infers the frequency illusion and the halo effect from behavioural and financial traces, which is a weaker form of evidence than direct measurement. Section 11 proposes designs that would remedy this. The third is the estimate problem. Franchise valuations are opinions produced by analysts. If those analysts are themselves subject to the halo effect, then the valuation figures used as evidence of the halo are partly a product of it. This is not fatal to the argument, and is in fact consistent with it, but it means the figures should be read as market perception rather than intrinsic worth. 5. The Baseline: Inter Miami Before the Halo To assess the magnitude of the change, the starting point must be described honestly. Inter Miami CF entered Major League Soccer in 2020, co owned by a group that included David Beckham. It played its home matches in a modest stadium in Fort Lauderdale rather than in Miami. Its early seasons were unremarkable, and it was sanctioned by the league for breaching roster and salary rules. It had won nothing. In the first half of the 2023 season it occupied last place in the Eastern Conference. Commercially, the club was a mid tier asset. Sportico's valuation before Messi's arrival was around 585 million dollars, a figure well behind Los Angeles FC, which had led MLS valuations for several consecutive years, and behind other established clubs such as Atlanta United and the LA Galaxy. Club revenue in 2022 has been estimated at approximately 56 million dollars. Nothing about this profile suggested an imminent leap to the top of the league's financial table. The club had no championship pedigree, no large permanent venue, no dominant local television market, and no global following. Whatever happened next cannot be attributed to accumulated sporting capital, because there was very little of it. The one asset the club did possess was a pink and black #brand_identity that was visually unusual and, until 2023, largely wasted. It was a loaded weapon without a trigger. 6. Stage One Evidence: Manufacturing the Red Car Effect 6.1 The Announcement as Encoding Event On 7 June 2023, Messi announced that he intended to join Inter Miami. The importance of this date is not sporting, since no match was played and no team improved. Its importance is cognitive. On that date, hundreds of millions of people encoded a previously ignored entity. The resale price data cited in Section 2 shows movement from that week, not from the week of his debut. The market responded to an act of encoding, not to an act of football. This is the empirical signature of stage one. If the value being created were athletic, the response would follow performance. It did not. It followed attention. 6.2 The Anchor in Operation Once encoded, the pink shirt began to function as a perceptual anchor across contexts that had nothing to do with Major League Soccer. It appeared in fashion photography, in music, on streets far from Florida, in social media feeds, and in the wardrobes of people who could not name a single other player on the team. Reports through 2024 and 2025 consistently described the shirt as among the best selling in world football. The key theoretical point is that the shirt travelled independently of the sport. A person who has never watched an MLS match can still recognise the shirt. This is exactly what an anchor is supposed to do: it detaches recognition from comprehension. The consumer does not need to understand the league to notice the brand, and noticing is stage one's only requirement. 6.3 Celebrity Attendance as Manufactured Sightings The second component of stage one was the systematic presence of high profile figures at matches. Musicians, actors, athletes from other sports, and business figures were reliably photographed at Inter Miami fixtures, and those photographs circulated far beyond sport media. The mechanism here is subtle and deserves precision. #celebrity_attendance does not persuade anyone that the football is good. It is not an argument. It functions instead as a distribution channel. Each celebrity carries an audience that would not otherwise have encountered the club, and each photograph places the pink anchor in front of that audience in a context where it is not perceived as advertising. The result is repeated exposure without the resistance that advertising normally triggers. Repeated exposure in unrelated contexts is precisely the condition under which the frequency illusion flourishes. The consumer does not think, this brand is being marketed to me. The consumer thinks, this club seems to be everywhere. The first thought produces scepticism. The second produces the sense of an unstoppable cultural fact. 6.4 Distribution: Streaming and the Algorithm The third component was structural. Major League Soccer had entered a global streaming arrangement that placed every match on a single platform accessible worldwide. This meant that the attention generated by the announcement could be converted immediately into consumption, without the friction of territorial broadcast rights, blackout rules, or fragmented schedules. A viewer in Jakarta, Lagos, or Dubai who encoded the club on Monday could watch it on Saturday. Alongside this, the club's content strategy was optimised for platforms whose recommendation systems reward engagement. The relevant property of #social_media_algorithms is that they do not distribute content evenly; they amplify what is already being engaged with. This means that the frequency illusion, once initiated, is not merely a private mental event. It is reinforced by machines that literally do show the consumer more of what they have noticed. The subjective illusion and the objective feed converge, and the consumer's impression of ubiquity becomes partly self fulfilling. This is an important refinement to the classical theory. In a pre algorithmic environment, the frequency illusion was purely internal: the world had not changed, only the filter. In an algorithmic environment, noticing something changes what the world shows you. The illusion acquires a real substrate. The consumer who feels that Inter Miami is everywhere is, in a narrow and personalised sense, correct. 6.5 Assessment of Proposition 1 The evidence supports Proposition 1. The club achieved perceived ubiquity that far exceeded its objective importance in the global football landscape. It remained a young club in a league that is not among the world's strongest, yet it occupied a share of global attention comparable to far more successful institutions. Perceived presence and actual presence had come apart, which is the definition of the frequency illusion. 7. Stage Two Evidence: The Halo Crosses From Player to Firm 7.1 Why This Halo Was Unusually Strong Halo transfer requires a source trait that is salient, positive, and difficult to contest. Messi's footballing reputation satisfies all three conditions to an unusual degree. Debate about the greatest player of the modern era is not a debate about whether Messi is excellent; it is a debate about who ranks first among two or three universally acknowledged greats. There is, in practical terms, no meaningful constituency arguing that he is not exceptional. Furthermore, his public reputation is comparatively free of scandal. This matters directly for the diminishing halo phenomenon identified by Cui et al. (2025), in which negative events erode transfer. A source trait that is both maximally positive and minimally contested is close to the theoretical ideal for halo generation. 7.2 The Transfer Channels The halo travelled through at least five channels. From player to squad. Teammates were re evaluated on the basis of proximity. Players who had been regarded as ordinary MLS professionals were reinterpreted as members of a serious footballing project. The experimental finding of Pan et al. (2025), that identity information inflates the perceived quality of identical actions, generalises naturally: if a name inflates the rating of a play, an association may inflate the rating of a colleague. From player to management and ownership. The ownership group was re described in public discourse as visionary rather than merely ambitious. Nothing about the ownership's competence had been demonstrated between the day before the announcement and the day after. Only the perception changed. From player to venue and infrastructure. A stadium that had been described as modest became, in coverage, an intimate venue at which one could see the greatest player in the world at close range. The physical facts were unchanged. The interpretation of those facts inverted. From player to league. The halo did not stop at the club. Major League Soccer as a whole was re framed from a retirement destination into a legitimate competition. This is #legitimacy transfer, and it is the perceptual counterpart to the superstar externality that Schreyer and Singleton (2025) measured in attendance terms. From player to commercial partners. Sponsors did not merely buy exposure. They bought association with an unimpeachable figure, and they were willing to pay a premium for that association well above what the club's audience size alone would have justified. 7.3 Sponsorship and the Repricing of Association The sponsorship response is the clearest commercial evidence of stage two, because sponsorship prices are negotiated by professionals with access to audience data. In principle these are exactly the actors least likely to be swayed by bias. Yet the club's #sponsorship portfolio was rebuilt at valuations that were not obtainable a year earlier, and the partners recruited were global brands rather than regional ones. Commercial revenue estimates for the club rose to a level that placed it among the leading clubs in the league in a category where it had previously been unremarkable. The behavioural point is that a sponsorship is not purchased on impressions alone. It is purchased on the perceived character of the association. A brand that appears alongside Messi is understood by its own customers to be a brand of a certain standing. The sponsor is buying a halo for itself, which it can only do by first paying the price of the halo it is borrowing. This is a second order cognitive market: the club sells attention, but it also sells reputation, and reputation is priced by perception, not by audit. 7.4 Valuation Analysts and the Reflexive Loop Franchise valuation involves projecting revenue, assessing brand strength, estimating the value of stadium related businesses, and applying a multiple. Every one of these steps involves judgment. As Kahneman et al. (2021) argue, such judgments are both biased and noisy. Once analysts began describing Inter Miami as the league's most valuable franchise, that description became an input into the next set of judgments. Investors seeking minority stakes negotiated against a reference point that was itself a product of perception. This is the reflexive loop that underlies most #franchise_valuation in modern sport: the estimate influences the market, and the market then validates the estimate. 7.5 Assessment of Proposition 2 The evidence supports Proposition 2. The evaluation of the club improved across attributes that Messi could not possibly have affected, including ownership competence, infrastructure quality, organisational professionalism, and league prestige. Judgment on all attributes moved together, which is the diagnostic signature of the halo effect first identified by Thorndike more than a century ago. 8. The Financial Record 8.1 Franchise Valuation Before Messi, Sportico's estimate of the club's value was approximately 585 million dollars. In its valuations published in early 2026, Sportico placed Inter Miami first in Major League Soccer at 1.45 billion dollars, an increase of about 22 percent year on year, which was the highest growth rate in the league, and the first time the club had led the ranking. Los Angeles FC, which had held first place for several years, was second at approximately 1.4 billion dollars. The wider context is essential to the argument. In the same valuation cycle, the average MLS club was valued at about 767 million dollars, up around 6 percent year on year. The bottom twelve clubs rose on average by roughly 2 percent, and several clubs fell in value. The rising tide explanation therefore fails. If league wide factors such as the approaching World Cup or general sport asset inflation were driving Inter Miami's gains, comparable gains should appear across the league. They do not. The distribution is not shifting; its top end is being pulled away from the rest. 8.2 Revenue Club revenue has been estimated at approximately 56 million dollars in 2022, roughly 190 to 200 million dollars by the 2025 season, and is projected by some analysts to approach 250 million dollars in the near term. This represents an approximate quadrupling in three years, in a league with a salary cap architecture explicitly designed to prevent exactly this kind of divergence. The composition of that revenue matters as much as its size. Growth came from matchday income, from commercial and sponsorship income, and from new business lines such as international touring, in which the club sells its appearance to overseas promoters. Touring revenue is particularly instructive for this paper, because a touring fee is not paid for a competitive fixture. It is paid for the right to host an attention event. It is, quite literally, the sale of salience. 8.3 Ticket Prices and Attendance The Journal of Sport Management study cited earlier estimated that Messi's arrival raised Inter Miami home resale prices by roughly 1,100 to 1,240 percent and away resale prices by roughly 410 to 480 percent in 2023. These are not marginal adjustments. They are order of magnitude changes in #willingness_to_pay for the same physical product: a seat in a stadium. On the attendance side, road matches involving Inter Miami repeatedly set club records for their hosts, with reported crowds exceeding seventy thousand in Kansas City and sixty five thousand in Foxborough. Opposing clubs moved fixtures to larger venues to capture the demand. The club's own average attendance rose to the limits of its facility, which is why resale prices are the better indicator: the physical constraint hides the true scale of demand. 8.4 Merchandise The club's shirt became one of the best selling in the world, a position no MLS club had previously approached. The relevant observation is again about detachment: the shirt sold in markets with no connection to Miami, to Florida, or to American football culture. #jersey_sales of this kind do not measure fandom in the traditional sense. They measure participation in a visible cultural signal. 8.5 Assessment of Proposition 3 The evidence supports Proposition 3. Perception driven indicators moved first and moved hardest. Resale prices moved in June 2023, within days of an announcement. Valuation, sponsorship, and merchandise followed within months. Sporting achievement followed later, with a continental cup in 2023 and a league championship in the 2025 season. The ordering is unambiguous, and it is the reverse of what a talent based model predicts. 9. Discussion: The Fragility of Engineered Perception 9.1 Borrowed Value The central strategic problem with halo derived value is that it is borrowed rather than owned. The club did not generate the reputation it monetised. It rented it, and it rented it from a single individual who is, at the time of writing, in the final phase of a long career, with a contract that runs through the 2028 season. This creates #key_person_risk of an unusually concentrated kind. Ordinary key person risk concerns the loss of an executive whose skills are hard to replace. Here, the asset at risk is not a skill set but a perceptual anchor. When the anchor departs, stage one begins to reverse: the club stops appearing in contexts unrelated to football, the algorithmic amplification decays, and the frequency illusion fades. Stage two then follows, because the halo has no source to emanate from. 9.2 What Might Survive Not all of the gain is necessarily temporary. Several assets acquired during the halo period are durable in themselves. Infrastructure is real. A completed stadium and training complex does not disappear when a player retires. Contracts are real. Multi year sponsorship agreements signed at halo era rates continue to pay after the halo dims, at least until renewal. Habits are partly real. A supporter who began following the club in 2023 and who has since attended matches, bought shirts, and joined a supporters group has developed #fandom that is now partly independent of its origin. Data is real. A customer base of several million, once acquired, can be marketed to at low cost. The honest question is one of proportion. If the ordinary, non halo value of a well run MLS club with good infrastructure and a large market is somewhere in the region of the league's upper tier but not far beyond it, then a substantial portion of the current valuation premium is contingent. The market appears to be aware of this. Reporting around the club's finances has repeatedly noted the concern among league insiders about what happens after Messi, and the contract extension through 2028 was widely described as a postponement of that question rather than an answer to it. 9.3 The Diminishing Halo and Reputational Exposure Cui et al. (2025) show that halos are reversible. A negative event involving the source can transfer negatively, especially where consumers attribute the event to the person's character rather than to circumstance. The stronger the halo, the greater the exposure, because more of the enterprise's perceived value is concentrated in one reputation. This produces a paradox for management. The rational response to halo dependence is to diversify the sources of perceived value, but every additional dollar invested in the halo produces a higher immediate return than any diversification effort, because the halo is already priced by the market and diversification is not. Firms in this position tend to over invest in the very dependency they should be reducing. The #diminishing_halo is therefore not merely a risk to be managed but a structural temptation to be resisted. 9.4 The Succession Problem The succession problem in halo dependent firms is not a recruitment problem. It is a perceptual one. A club cannot simply sign another very good player, because very good is not the relevant category. The halo requires a source trait that is salient, positive, and effectively uncontested. There are, at any given moment, perhaps two or three individuals in world football who meet that standard, and they are not generally available. The realistic strategies are therefore three. First, convert attention into institutional assets while the attention lasts, which is what stadium development and long term sponsorship agreements are designed to do. Second, transfer the anchor from the individual to the visual identity itself, so that the pink shirt eventually signifies the club rather than the player. Third, accept a controlled decline in valuation and manage expectations accordingly. Only the first two are strategies. The third is an outcome. 9.5 Cognitive Economics as a Field The Inter Miami case suggests a broader analytical position, which this paper terms cognitive economics: the study of how market value is created, sustained, and destroyed by the systematic properties of human judgment rather than by the underlying properties of the goods being judged. This is distinct from behavioural finance, which typically studies how bias causes prices to deviate from fundamental value. Cognitive economics, as used here, makes a stronger claim. In markets for attention goods, perception is not a distortion of fundamental value. It is the fundamental value. There is no true, bias free valuation of a football club sitting underneath the perceived one, because a football club's worth consists almost entirely of what people believe about it. A stadium has a replacement cost. A brand does not. 9.6 The Ethical Question If bias can be engineered, should it be? The defensible position is that a firm which supplies a genuinely excellent product and uses salience to ensure that consumers notice it is doing nothing objectionable. Attention is scarce, and competing for it is legitimate. Messi's excellence is real, the football is real, and consumers who buy tickets receive what they expected. The uncomfortable position concerns the sponsors, the minority investors, and the analysts, who are being asked to price an organisation on the basis of a trait that belongs to one employee and that says nothing about the organisation's operational quality. The halo effect is, definitionally, an error of inference. Constructing a business model that depends on other people committing that error raises a question that the sport business literature has largely avoided. There is also a distributional dimension. The same valuation cycle that rewarded Inter Miami saw several clubs stagnate or decline. Attention is a rival good: what one club gains in notice, another loses. A league in which one club captures a disproportionate share of global attention may find that the competitive balance which underpins its long term product is quietly eroded. The Matthew effect documented by Biegert et al. (2023) at the individual level appears to operate at the organisational level too. 10. Contributions 10.1 Theoretical Contributions This paper makes three contributions to theory. First, it integrates two literatures that have developed in isolation. Attention research explains why things get noticed. Halo research explains how noticed things get judged. Neither alone explains value creation. The Notice Then Judge model specifies their sequence and their interaction, and argues that the sequence is not reversible. Second, it extends halo theory from the product level to the firm level. The endorsement literature has long studied transfer from celebrity to product. This case demonstrates transfer from an individual to an entire organisation, including its ownership, its physical assets, its management, and its competitive league. This is a substantially larger claim than the endorsement literature has typically made, and it suggests that halo transfer is bounded by proximity and association rather than by any logical relationship between the source trait and the target attribute. Third, it identifies an algorithmic modification of the classical frequency illusion. In the original formulation, the environment is constant and only the filter changes. Where recommendation systems mediate exposure, noticing an object causes the environment itself to present that object more often. The illusion is thereby partially converted into fact. This is a meaningful update to a fifty year old cognitive concept, and it deserves direct experimental study. 10.2 Managerial Implications For practitioners, the case yields several transferable principles. Own a distinctive perceptual anchor before you need it. The pink shirt was valuable in 2023 precisely because it already existed and was unique. A brand cannot invent an anchor at the moment of a triggering event; the anchor must be waiting. Distinguish attention from persuasion. Celebrity attendance did not argue for the club's quality. It placed the club in front of audiences in contexts that bypassed advertising scepticism. Managers who evaluate such activity by conversion metrics alone will systematically undervalue it. Recognise that halo value is rented. Treat it as a financing event, not as an operating result. The correct use of a halo period is to convert perceptual capital into assets that outlive it, primarily infrastructure, long term contracts, customer relationships, and data. Do not confuse the analyst's estimate with the market's clearing price. A valuation is a judgment. In a halo period, judgment is inflated in the same direction for everyone at once, which is precisely when it feels most reliable and is least so. 10.3 Implications for Leagues and Regulators Leagues that permit or encourage superstar concentration should understand that they are trading league wide legitimacy gains for competitive and financial divergence. The Ronaldo and Clark studies show that a star lifts everyone somewhat. The Inter Miami valuation data shows that a star lifts his own club enormously and everyone else marginally. Over time, the ratio between those two effects determines whether the league is being grown or being hollowed out. 11. Limitations and Future Research The limitations set out in Section 4 constrain the strength of the conclusions. Attribution cannot be fully resolved without a counterfactual. Cognitive mechanisms are inferred from behaviour rather than observed. Valuation figures are estimates produced by analysts who may themselves be subject to the bias under study. Five research directions follow. First, experimental measurement of the halo transfer. Participants could be shown identical descriptions of a football club, its stadium, its ownership, and its management, with the presence of a superstar player manipulated between conditions. If ratings of ownership competence rise when the player is present, the transfer is established directly rather than inferred. Second, an event study of announcement effects. Where publicly traded companies sponsor a halo generating club, share price reactions to the announcement provide a clean market based measure of perceived value transfer. Third, longitudinal tracking through the post Messi transition. The departure of the halo source is a natural experiment. The decay curve of attention, sponsorship renewal rates, resale prices, and valuation after his eventual retirement will provide the strongest available test of Proposition 4. Fourth, algorithmic exposure studies. Direct measurement of how recommendation systems alter individual exposure following an encoding event would test the modified frequency illusion proposed in Section 10. Fifth, comparative cases. Beckham at the LA Galaxy, Ronaldo in Saudi Arabia, Clark in the WNBA, and Messi in Miami form a family of cases that vary in the strength of the anchor, the credibility of the source, and the quality of the distribution infrastructure. Systematic comparison would allow the boundary conditions of the model to be specified rather than asserted. 12. Conclusion Inter Miami CF did not become the most valuable club in Major League Soccer because it became the best team in Major League Soccer. It became the most valuable club because it became the most noticed one, and because what people noticed was attached to a man whose excellence nobody disputes. The mechanism was sequential and it was engineered. A distinctive pink anchor, held in reserve for years, was activated by an announcement that gave hundreds of millions of people a reason to encode a club they had previously ignored. Once encoded, the club appeared everywhere, in feeds, in photographs, in music, on streets, in conversations, and the frequency illusion did what it always does: it converted a change in attention into an impression of inevitability. Then the halo did its work. A single, salient, uncontested positive trait, the genius of one footballer, was extended across every attribute of an organisation that had earned none of it, and the market priced the extension. The financial record is consistent with this reading and difficult to reconcile with any other. Resale prices moved before a match was played. Valuation moved before a trophy was won. Sponsorship moved before the squad was rebuilt. The commercial revaluation ran ahead of the sporting one at every point, which is exactly what a cognitive model predicts and exactly what a talent model cannot explain. The lesson is not that the football was irrelevant. Without genuine excellence there is no halo to transfer, and a fraudulent anchor would have collapsed under scrutiny. The lesson is that excellence alone does not produce a billion dollar revaluation in thirty months. Excellence plus salience plus transfer does. That combination is reproducible, and it is being reproduced across sport and entertainment with increasing deliberateness. What remains unresolved is durability. Value that is borrowed must eventually be returned. The club has, on current evidence, a limited window in which to convert perceptual capital into the kind of capital that does not retire. Whether it does so will determine whether the Messi era is remembered as the moment a franchise was built or as the moment a franchise was briefly, spectacularly, and expensively imagined. Hashtags #cognitive_economics #frequency_illusion #halo_effect #Red_Car_Effect #Messi_Effect #Inter_Miami #Major_League_Soccer #selective_attention #confirmation_bias #availability_heuristic #salience #cognitive_spillover #superstar_economics #superstar_externality #spillover_effect #status_bias #Matthew_effect #behavioral_economics #consumer_perception #perceived_quality #willingness_to_pay #brand_identity #visual_branding #pink_jersey #celebrity_attendance #social_media_algorithms #sponsorship #franchise_valuation #jersey_sales #fandom #legitimacy #reputation #key_person_risk #succession_risk #diminishing_halo #heuristics #case_study #secondary_data #triangulation #sport_finance #attention_economy #brand_equity #ticket_pricing #attendance_demand #media_saturation #market_dominance #cognitive_bias #consumer_psychology #sport_management #global_branding References Biegert, T., Kuehhirt, M., and Van Lancker, W. (2023). They can't all be stars: The Matthew effect, cumulative status bias, and status persistence in NBA All Star elections. American Sociological Review, 88(2), 314 to 344. Cui, Y., van Esch, P., Eskridge, B., Ladlow, C., and Northey, G. (2025). The diminishing halo effect: Celebrities and negative events in marketing. Business Horizons, 68(2), 181 to 195. Deutscher, C., Neuberg, L., and Thiem, S. (2023). Who's afraid of the GOATs? Shadow effects of tennis superstars. Journal of Economic Psychology, 99, article 102663. Egger, M., and Florack, A. (2022). Investigating the mechanisms by which selective attention affects subsequent preferences and choice. Scientific Reports, 12, article 19345. Gnagey, M., and Koford, B. C. (2026). Superstar effects in the WNBA: Is Caitlin Clark the first WNBA superstar? Journal of Sports Economics, advance online publication. Hariningsih, E., Haryanto, B., Wahyudi, L., and Sugiarto, C. (2025). Ten years of evolving traditional versus non traditional celebrity endorser study: Review and synthesis. Management Review Quarterly, advance online publication. Jedelhauser, F., Flepp, R., and Franck, E. (2023). Overshadowed by popularity: The value of second tier stars in European football. Journal of Sports Economics, 24(8), 1026 to 1054. Kahneman, D., Sibony, O., and Sunstein, C. R. (2021). Noise: A Flaw in Human Judgment. New York: Little, Brown Spark. Nisbett, R. E., and Wilson, T. D. (1977). The halo effect: Evidence for unconscious alteration of judgments. Journal of Personality and Social Psychology, 35(4), 250 to 256. Noor, N., Beram, S., Khoo Chee Yuet, F., Kannan, S., and Mohd Salleh, M. F. (2023). Bias, halo effect and horn effect: A systematic literature review. International Journal of Academic Research in Business and Social Sciences, 13(3), 1116 to 1140. Pan, Y., Pereira, M. H., Gomez Gonzalez, C., and Dietl, H. M. (2025). The superstar effect on perceived performance in professional football: An online experiment. Journal of Economic Psychology, 106, article 102776. Rosen, S. (1981). The economics of superstars. American Economic Review, 71(5), 845 to 858. Schreyer, D., and Singleton, C. (2025). Cristiano of Arabia: Did Ronaldo increase Saudi Pro League attendances? Contemporary Economic Policy, 43(2), 260 to 270. Stephenson, E. F. (2024a). Caitlin Clark's surprising economic impact. Economics Letters, 243, article 111926. Stephenson, E. F. (2024b). International competitions, star players, and NWSL attendance. Journal of Sports Economics, 25(2), 186 to 199. The star effect of Lionel Messi on secondary market ticket prices in Major League Soccer. (2025). Journal of Sport Management, 40(3), 207 onwards. Thorndike, E. L. (1920). A constant error in psychological ratings. Journal of Applied Psychology, 4(1), 25 to 29.

The transfer of Lionel Messi to Inter Miami CF in July 2023 produced one of the fastest increases in franchise value ever recorded in North American professional sport. In roughly thirty months, a club that had never won a trophy and sat at the bottom of its conference moved from an estimated value of about USD 585 million to about USD 1.45 billion, becoming the most valuable club in Major League Soccer. This article argues that the standard economic explanation, which treats the increase as a rational repricing of expected future cash flows, is incomplete. It proposes a two stage behavioural model in which value creation begins with attention and only later becomes judgment. In the first stage, an engineered #frequency_illusion, popularly known as the red car effect, made the club impossible not to notice: a distinctive #pink_jersey, a globally streamed league product, celebrity attendance, and an unusually theatrical unveiling turned every media surface into a reminder of the same organisation. In the second stage, the #halo_effect took over. Because Messi is widely regarded as one of the greatest players in the history of the sport, observers transferred that perception of excellence from the athlete to the organisation that employed him, and began to treat Inter Miami as though it were, in every dimension, a world class business. Using an interpretive single case design and triangulated secondary evidence, including independent valuation estimates, published revenue and attendance data, sponsorship structures, and a peer reviewed study of secondary market ticket prices, the article shows how the club and the league deliberately built commercial architecture, in particular pre negotiated sponsorship escalator clauses and staggered contract expiries, that converted borrowed attention into contracted revenue before the halo faded. The analysis contributes a three step mechanism, salience, transfer, capitalisation, that links behavioural economics to #franchise_valuation, and it identifies the danger of the same mechanism running in reverse once the athlete departs. Keywords: halo effect; frequency illusion; salience; superstar economics; franchise valuation; Major League Soccer; sport marketing; behavioural finance; brand equity; celebrity endorsement 1. Introduction On 7 June 2023, a short announcement changed the price of an American sports business. #Lionel_Messi, the winner of the 2022 FIFA World Cup and, by most accounts, the most decorated footballer of his generation, said that he intended to join Inter Miami CF. He signed in July of that year. At the time, the club was five years old as a legal entity and three seasons old as a competitive one. It had never won a trophy. It sat last in the Eastern Conference of #Major_League_Soccer, and it was known, if at all, as #Inter_Miami, the pink club with the famous co-owner. Independent estimates placed its value at roughly USD 585 million, a figure that ranked it in the middle of a league that itself was still arguing for global relevance. What followed is now a standard reference point in sports business teaching. Within about seven months, the club's estimated value crossed one billion dollars. Within about thirty months, it stood at approximately USD 1.45 billion, the highest in the league, ahead of a rival that had held the top position since such rankings began. Reported revenue rose from roughly USD 56 million in 2022 to more than USD 100 million in 2023 and to an announced target of about USD 200 million in 2024, a figure that would place a #Major_League_Soccer club among the highest earning football clubs in the world. The conventional reading of these numbers is straightforward. Messi is a #superstar, superstars raise demand, higher demand raises revenue, and higher revenue raises the #brand_equity and the value of the asset that owns the revenue. This reading is not wrong. It is, however, insufficient. It cannot explain the speed of the repricing, which happened long before most of the incremental cash had actually been earned. It cannot explain why the perceived quality of everything else about the organisation, its management, its stadium project, its sporting model, its long term competitive position, seemed to improve in the public and investor mind at exactly the moment when only one input to the business had changed. And it cannot explain why the same league that celebrated a 22 percent rise in the value of its most visible club also saw the bottom twelve clubs rise by an average of only about 2 percent in the same period. Rational repricing distributes itself across a league that shares media revenue. Attention does not. This article proposes that the Inter Miami case is best understood as a controlled demonstration of two #cognitive_bias mechanisms operating in sequence, and that the club's management, whether by design or by instinct, built a commercial structure that captured the financial output of both before either could decay. The first mechanism is the #frequency_illusion, the tendency to perceive something as suddenly ubiquitous once it has been flagged as personally relevant. The linguist Arnold Zwicky named the effect in 2005, and popular writing calls it the red car effect: buy a red car, and the roads appear full of red cars. The cars were always there. Your filter changed. The second mechanism is the #halo_effect, first documented in psychological ratings in the early twentieth century, in which a single strong impression of one attribute contaminates the assessment of unrelated attributes. A person judged to be attractive is also judged, without evidence, to be intelligent and kind. A firm judged to be successful is also judged to have excellent leadership, culture, and strategy. The argument of this article is that the two effects were not independent. They were sequential and complementary. The #red_car_effect solved the first problem any small franchise faces, which is that nobody is looking. It did so through a set of highly distinctive and repeatable visual and social cues: a pink shirt in a league of blues and reds, a globally distributed streaming product with a single obvious protagonist, celebrities in the stands, and an unveiling staged as spectacle rather than as press conference. Once the public was looking, the #halo_effect solved the second problem, which is that looking is not the same as believing. Because the object of the gaze was a player of extraordinary and unambiguous quality, the quality judgment travelled outward from the player to the badge, from the badge to the balance sheet, and from the balance sheet to the valuation multiple. The article makes three contributions. First, it develops an explicit three step mechanism, salience, transfer, capitalisation, that connects behavioural economics to the literature on #franchise_valuation, which has historically been dominated by hedonic and market comparable models that assume value is a function of observable financial and market fundamentals. Second, it provides a structured, source based reconstruction of how Inter Miami built contractual machinery, most notably escalator clauses written into sponsorship agreements years before Messi arrived, that was designed to convert a temporary attention shock into durable revenue. Third, it identifies the symmetry problem: a valuation built on borrowed perception is exposed to the reverse halo, and the article sets out the observable indicators that would allow students and analysts to detect whether the club's value has become structurally independent of the player. The remainder of the article is organised as follows. Section 2 provides the background on the club and the league. Section 3 reviews the relevant literature in superstar economics, attention and salience, the #halo_effect, and franchise valuation. Section 4 develops the conceptual framework and states the propositions. Section 5 sets out the method and its limits. Section 6 presents the analysis. Section 7 discusses the findings, including the strongest counter argument, which is that everything described here is rational. Section 8 sets out implications, and Section 9 concludes. 2. Background: A Club Without a Reason to Be Noticed Inter Miami CF began play in 2020 as an expansion franchise in #Major_League_Soccer, a league that operates on a single entity structure with a salary budget, allocation mechanisms, and a limited number of exceptions for high earning players. The club's most visible founding figure was David Beckham, himself the subject of the most famous previous attempt to import global attention into American soccer, and its controlling investors were Jorge and Jose Mas. The early years were unremarkable in sporting terms and difficult in reputational terms. The team missed the playoffs, changed coaches, absorbed a sanction relating to roster rules, and by the middle of 2023 sat at the bottom of the Eastern Conference. It played at a temporary venue in Fort Lauderdale while its permanent home, Miami Freedom Park, remained a construction and permitting story rather than a physical one. Its estimated value, roughly USD 585 million, was respectable for a young franchise in a growing league, but it carried no premium. There was no trophy, no continental pedigree, and no claim on the attention of anyone outside South Florida. Two structural facts about the league matter for what follows. The first is the media architecture. In 2023, #Major_League_Soccer began a ten year partnership with Apple under which every match was distributed globally through a single subscription product, MLS Season Pass, with the league reported to receive at least USD 2.5 billion over the term of the agreement. This is unusual. In most leagues, a superstar's matches are scattered across national broadcasters, regional networks, and geoblocked rights packages. Here, a single global storefront existed, and it had one obvious thing to sell. When Messi arrived, the subscriber count of that product is reported to have doubled. The league had, without necessarily intending it, built the perfect #attention_economy distribution channel and then acquired the perfect protagonist for it. The second is the economics of the league itself. #Major_League_Soccer does not have the national media revenue of the National Football League or the National Basketball Association. Reporting indicates that clubs net only a small share of the Apple revenue after production costs, and that more than half of the league's teams have historically operated at a loss, with owners funding the shortfall. In such a league, the value of a franchise is not primarily a discounted stream of realised profits. It is closer to a scarcity asset, an option on the future of the sport in North America, priced by what a small number of very wealthy buyers believe a seat at the table will be worth later. That distinction is central to the argument here, because scarcity assets priced on belief are precisely the assets most exposed to #cognitive_bias. The club, then, entered July 2023 with a distinctive visual identity, a global distribution pipe, a valuation anchored in belief rather than in cash, and no reason at all for the world to look at it. The intervention that followed did not change the underlying league economics. It changed who was looking, and what they thought they were seeing. 3. Literature Review 3.1 Superstar economics and the demand for stars The economic foundation for the study of star athletes is Rosen's theory of superstars, which explains why small differences in talent generate enormous differences in reward in markets where a performer's output can be reproduced at near zero marginal cost and where consumers prefer a small amount of the best to a large amount of the merely good (Rosen, 1981). Adler (1985) offered a complementary and, for this article, more useful account: stardom can arise from the accumulation of consumption capital and shared conversation rather than from talent alone. In Adler's framing, people prefer to consume what other people are consuming, because the enjoyment of a star depends on being able to discuss the star with others. Stardom is therefore partly a coordination phenomenon, and it can be manufactured or accelerated by anything that makes the star more visible. Empirical work in sport economics has repeatedly found that star presence increases attendance and viewership. Lucifora and Simmons (2003) documented superstar effects in Italian football. Later research extended the finding across sports and contexts, including gymnastics (Meissner, Rai and Rotthoff, 2021), the Saudi Pro League following the arrival of Cristiano Ronaldo (Schreyer and Singleton, 2025), and the Women's National Basketball Association following the arrival of Caitlin Clark (Gnagey and Koford, 2026), where the estimated attendance effect exceeded that attributed to Michael Jordan in earlier studies. In #Major_League_Soccer specifically, the closest historical analogue is David Beckham's move to the LA Galaxy in 2007, whose effect on ticket sales was estimated by Lawson, Sheehan and Stephenson (2008). The most directly relevant study is Gong and Watanabe (2025), who examined the effect of Messi's transfer on secondary market ticket prices across #Major_League_Soccer. Their estimates indicate that resale prices for Inter Miami home matches rose by between roughly 1,113 percent and 1,237 percent, and for Inter Miami away matches by between roughly 410 percent and 477 percent, in 2023. Two features of their findings deserve emphasis. First, the magnitude is far outside the range typically reported in the star effect literature. Second, the spillover to matches not involving Inter Miami was uneven, with several clubs showing insignificant or even negative changes in home game resale prices. The star did not lift the whole market. He concentrated it. This literature establishes that stars raise demand. It does not, on its own, explain how a demand shock for tickets becomes a doubling of enterprise value, nor why the perceived quality of the entire organisation improves. For that, we need theories of attention and of judgment. 3.2 Attention, salience, and the frequency illusion Behavioural economics has increasingly treated attention as a scarce resource whose allocation shapes choice. Bordalo, Gennaioli and Shleifer (2022) review the evidence that salient stimuli capture attention from the bottom up, through contrast with their surroundings, through surprise relative to what memory expects, and through sheer prominence, and they show how this distortion of attention can systematically distort economic choice. Their framework unifies a set of anomalies, including framing, reference points, and menu effects, as manifestations of the same underlying process: what is noticed is overweighted. The #frequency_illusion sits within this tradition. Named by the linguist Arnold Zwicky in 2005, and known informally as the Baader Meinhof phenomenon or the #red_car_effect, it describes the experience of encountering a newly noticed item everywhere immediately after first noticing it. It is generally explained as the joint product of two processes: selective attention, which begins filtering the environment for the newly flagged item, and confirmation bias, which then treats each sighting as evidence that the item really has become more common. The world did not change. The filter did. The link between attention and preference is not merely descriptive. Egger and Florack (2022) provide experimental evidence that selective attention to a stimulus shifts subsequent preferences and choices toward that stimulus. This is the crucial bridge for the present argument. If attention were purely perceptual, an engineered #frequency_illusion would produce awareness and nothing more. Because attention feeds preference, manufactured noticing becomes manufactured wanting, and manufactured wanting becomes willingness to pay. 3.3 The halo effect The #halo_effect was documented by Thorndike (1920), who found that officers rating soldiers on distinct attributes produced ratings that were far too highly correlated to be independent judgments. A strong global impression, positive or negative, bled into every specific assessment. Nisbett and Wilson (1977) demonstrated that the effect operates outside awareness: participants influenced by a global impression denied that it had influenced them, and instead constructed plausible reasons for their specific judgments. Rosenzweig (2014) applied the concept to business analysis, arguing that a large share of what is written about corporate strategy, leadership, and culture is halo driven. Analysts observe a firm's financial performance and then attribute to it whatever managerial virtues the narrative requires. When performance reverses, the same firm is retrospectively described as having had an arrogant culture and a complacent leadership, though nothing about the firm's internal processes may have changed. Kahneman, Sibony and Sunstein (2021) place the effect within a wider account of noise and bias in professional judgment, noting that halos are strongest when evaluators must judge attributes that are ambiguous, slow to verify, or unobservable. Franchise valuation is exactly such a domain. The quality of a club's management, its brand strength, its long term market position, and its option value in a growing sport are all unobservable, ambiguous, and slow to verify. Under these conditions, a single vivid, unambiguous signal of excellence can dominate the evaluation. Messi is precisely such a signal. His excellence is not contested, not context dependent, and not subject to interpretation. It is, in the language of the halo literature, an unusually clean global impression. In sport and marketing research, the halo mechanism appears under the heading of image transfer in celebrity endorsement. Platania et al. (2026) analysed the endorsement effects of globally recognised athletes, including Messi and Ronaldo, on the market performance and brand equity of sportswear firms, and reported findings consistent with both a #halo_effect and a congruence effect between athlete and brand. Hayat et al. (2024) examined how individual stardom and team loyalty interact in social network reflections around Messi and Ronaldo, showing that the audience relationship with the individual and with the club are entangled rather than separable. The endorsement literature has generally studied the transfer of athlete image to a product. The Inter Miami case involves the transfer of athlete image to the employing organisation itself, which is a stronger and less studied claim. 3.4 Franchise valuation The literature on the value of professional sports franchises has typically used hedonic and comparable sales approaches, modelling estimated or realised franchise prices as functions of market size, stadium characteristics, competitive performance, and league level revenue. This work is useful but rests on an implicit assumption: that estimated values reflect fundamentals in a reasonably stable way. In practice, the widely cited annual estimates published by financial media are constructed from revenue multiples, comparable transactions, and analyst judgment. They are not audited transaction prices. They function as focal points. Because sports franchises trade rarely and in thin markets, and because the buyer pool consists of a small number of ultra high net worth individuals and funds for whom the asset is partly a consumption good and partly a scarcity play, the published estimate can itself shape the price at which the next transaction occurs. This is the reflexive feature that makes the market unusually hospitable to the #halo_effect. If an estimate rises because analysts have revised their impression of a club, and a buyer then pays a price anchored on that estimate, the impression has become a fundamental. 3.5 The gap Three gaps emerge. First, the superstar literature measures demand effects on tickets and viewers but rarely traces the pathway from a demand shock to an enterprise value shock. Second, the salience literature explains how attention distorts choice but has not been applied to the valuation of sporting assets. Third, the halo literature has examined image transfer to products but not, in a structured way, to the employing franchise. This article addresses all three by building a sequential model and testing it against the richest available natural experiment. 4. Conceptual Framework: Salience, Transfer, Capitalisation The framework proposed here treats the transformation of Inter Miami as a three step process. The steps are ordered, and the order matters: attention must precede judgment, and judgment must precede pricing. 4.1 Step one: engineered salience (the red car effect) #Salience is manufactured when a target is made visually distinctive, contextually surprising, and repeatedly encountered across unrelated channels. The theoretical claim is that a #cognitive_bias which normally arises by accident, the sudden sense that something is everywhere, can be induced deliberately by controlling the cues that trigger selective attention. The instruments available to a football club are unusually rich. A kit colour that no competitor uses functions as a perceptual tag that the visual system can lock onto. A single global streaming product creates one place where the tag can be encountered by anyone, anywhere. Celebrity attendance imports the audiences of unrelated fame economies, so that the tag appears inside content streams that have nothing to do with sport. Away fixtures moved into large stadiums convert every rival's home match into an additional exposure event. Each channel on its own produces awareness. Together, they produce the specific subjective experience of ubiquity that defines the #frequency_illusion. Proposition 1. The perceived omnipresence of Inter Miami after July 2023 exceeded its actual increase in media output, because selective attention, once triggered, amplified the perceived frequency of a stable set of cues. Proposition 2. Because attention feeds preference (Egger and Florack, 2022), manufactured salience translated into willingness to pay, observable in secondary market ticket prices before any improvement in the club's underlying product had been demonstrated. 4.2 Step two: halo transfer Attention alone is neutral. It can produce ridicule as easily as reverence. What determines the sign of the effect is the quality of the object at the centre of the gaze. Here the object was an athlete whose excellence is as close to uncontested as anything in professional sport. The theoretical claim is that when a global impression of extreme quality is attached to an organisation, and when the organisation's other attributes are ambiguous and difficult to verify, evaluators will resolve the ambiguity in the direction of the global impression. They will not consciously reason that a club employing a great player must have great management. They will simply find that the club seems more impressive, and will then generate reasons, as Nisbett and Wilson (1977) predicted. Proposition 3. After July 2023, external assessments of Inter Miami's unobservable attributes, including managerial competence, brand strength, and long term market position, improved without any independent evidence of change in those attributes. Proposition 4. The halo transferred asymmetrically. It attached most strongly to the club that employed Messi, less strongly to the league, and negligibly or not at all to clubs that merely shared the league with him. 4.3 Step three: capitalisation The final step is the conversion of perception into contracted and capitalised value. This is where the case departs from a story about psychology and becomes a story about management. Attention decays. Halos fade or invert. The financial question is not whether a club can borrow perception, but whether it can lock the perception into instruments that survive its decay. Three mechanisms are available. The first is contractual: writing agreements whose payments rise automatically when a specified event occurs, so that the club does not need to renegotiate under time pressure. The second is temporal: timing the expiry of existing agreements so that the club returns to the market at the moment of maximum perceived value. The third is structural: converting temporary cash flow into permanent assets, such as a stadium, an academy, or a media property, which continue to generate revenue after the source of attention has gone. Proposition 5. Inter Miami's valuation rose faster than its realised revenue, indicating that the market was pricing perceived organisational quality and option value rather than delivered cash. Proposition 6. The durability of the valuation depends on the share of the attention shock that was converted into contracts and assets before the halo could decay. Where conversion is incomplete, the same mechanism will operate in reverse. Together, the six propositions describe a pipeline: engineered salience produces noticing; noticing produces preference; preference plus an uncontested quality signal produces a halo; the halo inflates the assessment of unobservable attributes; the inflated assessment is capitalised into a #valuation_multiple; and management races to convert that multiple into contracts and concrete before the mechanism decays. 5. Method 5.1 Design This is an interpretive single case study. The case is selected not because it is representative but because it is extreme, and extreme cases are diagnostically efficient: a mechanism that is weak in ordinary settings becomes visible when it is unusually strong. Inter Miami between June 2023 and early 2026 offers a rare configuration: a single, discrete, well dated intervention; a stable institutional environment, since league rules, media architecture, and market conditions did not change materially at the same moment; and a dense public record of financial and behavioural outcomes. 5.2 Data Evidence is drawn from four categories of secondary source. The first is peer reviewed research, principally Gong and Watanabe (2025) for ticket price effects, Schreyer and Singleton (2025) and Gnagey and Koford (2026) for comparable superstar effects, and the theoretical literature discussed in Section 3. The second is independent valuation estimates published by specialist financial media, principally the annual franchise valuations produced by Sportico and Forbes. These are estimates, not transaction prices, and Section 5.4 treats their limitations directly. The third is disclosed commercial information, including public statements by the club's business leadership regarding revenue targets, sponsorship structures, and contract design, together with reported league level data on attendance, sponsorship growth, merchandise sales, and subscription volumes. The fourth is the observable behavioural record: attendance figures, sellout counts, venue changes for away fixtures, merchandise rankings, and the pattern of media and celebrity attention. 5.3 Analytical strategy The analysis proceeds by pattern matching. For each proposition, the study identifies the observable implications that would follow if the proposition held, and then asks whether the record shows them. Where a rival explanation, principally rational repricing on fundamentals, would predict the same observation, the analysis identifies the discriminating evidence, that is, the observation on which the two explanations disagree. Section 7.1 is devoted to this comparison, because the strength of a behavioural claim depends entirely on whether it survives the rational alternative. 5.4 Limitations Three limitations must be stated plainly. First, published franchise valuations are estimates produced by third parties using proprietary methods. They are not audited, and Inter Miami is privately held. They are used here as a measure of market perception, which is appropriate for the argument, since the argument concerns perception, but they should not be read as the price at which the club would trade. Second, this is a single case, and causal identification is limited. The article does not claim to estimate a treatment effect. It claims to trace a mechanism. Third, #cognitive_bias cannot be observed directly. It is inferred from the gap between what changed and what people believed had changed. The inference is strongest when a belief moves without any corresponding change in the underlying attribute, and the analysis concentrates on such cases. 6. Analysis 6.1 Stage one: manufacturing the red car effect 6.1.1 The pink shirt as a perceptual tag Inter Miami plays in pink and black. In a league and a sport dominated by red, blue, white, and black, this is a deliberate act of visual differentiation, and it long predates Messi. Its function, in the terms of Bordalo, Gennaioli and Shleifer (2022), is contrast: pink is salient because it is unlike its surroundings. The importance of the #pink_jersey is that it makes the club recognisable in low information conditions. A viewer scrolling quickly does not read a badge. A viewer scrolling quickly registers pink. Once Messi was inside that shirt, the shirt became a portable, low cost identifier that could be recognised in a photograph, a highlight clip, a thumbnail, a replica worn in a street on another continent, or a still frame in an unrelated news bulletin. The club's merchandising results reflect this: the Messi shirt became the best selling item on the league's official store, and it held that position across successive seasons. Every one of those garments is not only a sale. It is an additional exposure surface, worn by a person walking through a city that may never have heard of the club before. This is the first component of an engineered #frequency_illusion. The cue is distinctive, easily learned, and reproducible at scale by people who are not paid to reproduce it. 6.1.2 A single global storefront The second component is distribution. The league's arrangement with Apple placed every match inside one global subscription product. When Messi arrived, the reported subscriber count of that product doubled. This is worth pausing on, because it is not the usual pattern. In a fragmented rights environment, a star's audience is dispersed and unmeasurable. Here, the audience was assembled in one place, counted, and made legible to sponsors and investors. A single storefront also produces repetition. Every match, everywhere, becomes an occasion for the same interface to promote the same protagonist to the same subscribers. The effect on perception is precisely the one the #frequency_illusion describes: the club appears to be everywhere, because within the environment where the observer now spends attention, it genuinely is. 6.1.3 Celebrity attendance and the borrowing of unrelated audiences The third component is the importation of audiences from outside sport. Messi's debut, and subsequent home matches, drew a stream of globally recognisable figures from music, film, and other sports. The commercial significance of this is not that celebrities buy tickets. It is that celebrity presence moves the club out of the sports section and into entertainment, fashion, and lifestyle content, where it is encountered by people who were not looking for football. This matters mechanically. A #frequency_illusion requires encounters across unrelated contexts. Seeing a football club repeatedly on a football channel produces awareness within a category. Seeing a football club in a fashion feed, a celebrity gossip cycle, a late night monologue, and a basketball player's social account produces the specific and disorienting sense that the thing is following you. That sense is the illusion, and it is the engine of perceived ubiquity. 6.1.4 The away fixture as a distribution event The fourth component turned the league's own schedule into an advertising network. As demand rose, opposing clubs moved fixtures against Inter Miami into larger venues. One 2023 fixture at Soldier Field drew more than 62,000 spectators and produced record ticket revenue for the host club, in a match Messi did not play. In April 2024, a match against Sporting Kansas City at Arrowhead Stadium drew 72,610 spectators. League wide, 2024 produced a record regular season attendance of about 11.45 million, an average of 23,234 per match, and 213 sellouts, with ten clubs setting or matching their own attendance records. The important observation is the Chicago match, where Messi did not appear and more than sixty thousand people attended anyway. That is not demand for a player. That is demand for proximity to a phenomenon. It is the clearest available evidence that what was being consumed had detached from the athletic product and become a cultural event, and it is the point at which the analysis must shift from superstar economics to the psychology of attention. 6.1.5 The price evidence The financial signature of stage one is visible in the secondary market for #ticket_prices. Gong and Watanabe (2025) estimate that Messi's arrival raised Inter Miami home match resale prices by roughly 1,113 to 1,237 percent and away match resale prices by roughly 410 to 477 percent in 2023. The resale market is a useful instrument precisely because it is not administered by the club. It is a decentralised measure of what strangers will pay, and it moved by an order of magnitude within weeks of an announcement, before a single competitive fixture had demonstrated that the team was any better. Proposition 2 is therefore supported. Attention converted into willingness to pay ahead of any verified improvement in the product. But Gong and Watanabe also report that the spillover to matches not involving Inter Miami was uneven, with many clubs seeing insignificant or negative changes in home resale prices. This is the first sign that what was happening was not a general repricing of the league's quality. It was a concentration of gaze on a single object, which is what Proposition 4 predicts. 6.2 Stage two: the halo takes over 6.2.1 From player excellence to organisational excellence The transition from noticing to believing occurred with remarkable speed, and it can be traced in the way the club was described. Before June 2023, Inter Miami was routinely characterised in the press as an underachieving expansion side with a celebrity owner, a stadium problem, and a roster sanction. After July 2023, the same organisation was described in the language of global football: an international brand, a super club in formation, a business operating at the level of the largest clubs in Europe. Nothing about the club's internal capabilities had been independently demonstrated to change in that interval. Its executives were the same. Its ownership was the same. Its stadium was still unfinished. Its league was still the same league, with the same salary structure and the same national media economics. What had changed was the presence of a single, unambiguous signal of excellence. The #halo_effect predicts exactly this pattern: a strong global impression contaminates the assessment of unrelated and unverifiable attributes (Thorndike, 1920; Nisbett and Wilson, 1977; Rosenzweig, 2014). Observers did not conclude, through analysis, that the club's management was world class. They perceived the club as world class, and then found reasons. Proposition 3 is supported. The most telling evidence for the unconscious character of the transfer is that the reasons offered were themselves reinterpretations of pre existing facts. The stadium project, previously a liability, was reframed as visionary infrastructure. The ownership group, previously the operators of a struggling franchise, were reframed as the executives who had executed the most audacious signing in the history of the sport. The pink shirt, previously a curiosity, was reframed as branding genius. The facts did not change. Their halo did. 6.2.2 The halo in the sponsorship market The clearest measurable trace of the halo is in the behaviour of corporate #sponsorship partners, because sponsors are professional evaluators who must justify their spending internally. Before Messi, Inter Miami's front of shirt partner was a cryptocurrency platform, a category that in that period signalled a club selling to whoever would pay. Within months of the transfer, the club replaced it with a global cruise line, and secured a naming rights partner for its stadium in the form of a major American bank. Reported sponsorship revenue was expected to roughly double from about USD 27 million in 2023, with the club's business leadership publicly comparing the value of its commercial deals to those of the largest clubs in Europe. Note what this involves. A sponsor buying the front of an Inter Miami shirt is not buying Messi. Messi is contracted for a defined period. The sponsor is buying a multi year association with an organisation, and pricing that association at a level that assumes the organisation will remain globally significant. That is the halo, expressed in a purchase order. The blue chip partners who arrived after July 2023 were not, in most cases, buying incremental cash flows they could observe. They were buying an entity whose perceived quality had been revalued by association. The same logic explains the club's ability to sign eleven multi year partnerships in a single year and to move from local and regional partners to global ones. The category of partner changed, and the category of partner is a market judgment about what kind of organisation the club is. 6.2.3 The halo did not travel far Proposition 4 predicts asymmetry, and the record shows it. The league as a whole benefited: attendance records, higher sponsorship revenue, more sellouts, higher subscription counts. But the distribution of the benefit was extraordinarily skewed. Valuation data indicate that while Inter Miami rose to approximately USD 1.45 billion, an increase of about 22 percent in a single year, the bottom twelve clubs in the league rose by an average of about 2 percent over the same period. The gap between the most and least valuable clubs widened to a ratio of roughly three to one. Gong and Watanabe's finding that many clubs experienced insignificant or negative changes in their own home resale prices points the same way. If the arrival of Messi had rationally revalued the league's future, the benefit would have been broadly shared, because the league shares its central media revenue and because the option value of any franchise in a rising league should rise together. It was not broadly shared. It concentrated on the club that had the ball, the shirt, and the player. This is what a #halo_effect looks like at the level of a market: it is bounded by the object of the impression and it does not diffuse to entities that merely resemble it. 6.3 Stage three: capitalisation, or how the club got paid before the halo faded The most interesting managerial content of this case is not that Inter Miami benefited from two biases. It is that the club appears to have built the plumbing to collect the proceeds in advance. 6.3.1 Escalator clauses According to the club's own business leadership, Inter Miami had for several years been negotiating sponsorship agreements that contained clauses raising the partner's payments automatically in the event that a player of Messi's stature joined the club. The club reportedly declined some sponsorship offers when a prospective partner refused to accept the clause. This deserves close attention, because it inverts the usual sequence. Normally, a club acquires a star, the star raises the club's commercial value, and the club then attempts to renegotiate its sponsorships upward, a slow process in which incumbents have contractual protection and the club has little leverage. By pre negotiating the escalator, the club converted a probabilistic future event into an automatic repricing. It sold the option on its own future salience before it had the salience. In behavioural terms, the club recognised that the moment of maximum perceived value would be brief and that the counterparties would be least able to resist a price increase precisely when they were most enthusiastic. The escalator removed the need to negotiate at that moment. The money arrived by operation of the contract. 6.3.2 Staggered expiries The second instrument was timing. The club structured several partnerships to expire at the end of the year in which Messi arrived, allowing it to return to the market at the peak of the halo, with a new global audience, a trophy, and a sold out stadium. The front of shirt deal was among those expiring. The result was that the club's most valuable commercial asset was placed on the market at the precise moment when the market's assessment of the club was most inflated. This is timing arbitrage against a bias. The club did not need to believe that the halo was permanent. It needed only to know when it would be brightest. 6.3.3 Converting attention into concrete The third instrument is the conversion of temporary revenue into permanent assets. Season ticket packages for the first full Messi season sold out in the preceding November. The temporary stadium's capacity was expanded from about 18,000 to about 21,550. Behind that, the permanent stadium project at Miami Freedom Park moved from a plan to a facility, funded and justified by demand that Messi had made visible. A #stadium_asset is the ideal instrument for capitalising a temporary attention shock, because it converts a stream of borrowed demand into a fixed asset with a forty year life. Even when the source of attention departs, the seats, the suites, the naming rights, and the events business remain. In the language of the framework, the club used stage one and stage two revenue to buy an asset that does not depend on stage one or stage two. 6.3.4 The valuation record The financial outcome can be summarised as follows. Pre Messi, the club was valued at approximately USD 585 million. Following the transfer, independent estimates placed it at approximately USD 1.02 to 1.03 billion, a rise of roughly 72 to 74 percent, making it one of the first clubs in league history to reach a billion dollar valuation. The following year it was estimated at about USD 1.2 billion, the fastest growth rate in the league. By early 2026 it was estimated at approximately USD 1.45 billion, the highest in the league, ahead of a rival at about USD 1.4 billion, at a time when total league franchise value reached about USD 23 billion and the average club stood at about USD 767 million. Revenue moved as well, but not at the same speed and not at the same time. Reported revenue rose from about USD 56 million in 2022 to roughly USD 118 to 127 million in 2023, with an announced target of about USD 200 million in 2024 and projections approaching USD 250 million by 2026. Proposition 5 concerns the relationship between these two series. The valuation approximately doubled within months of the announcement. The revenue took longer to arrive, and much of the initial revaluation was priced against revenue that had been announced as a target rather than delivered as a result. The market was not discounting realised cash. It was pricing a changed impression of what kind of organisation this was, and it was doing so at a multiple appropriate to a global club rather than to a mid table franchise in a league where most clubs lose money. That is capitalisation of a perception. It is Proposition 5, supported. 6.4 Summary of findings The evidence supports the sequence proposed in Section 4. A distinctive visual identity, a single global distribution channel, imported celebrity audiences, and a schedule that turned every away fixture into an exposure event combined to produce the subjective experience of ubiquity. That noticing translated into willingness to pay before the product improved, most visibly in the resale market. The uncontested excellence of the player then transferred to the organisation, changing the market's assessment of attributes that no one had actually measured, most visibly in the class of sponsor willing to attach itself to the club. And the club, having anticipated the moment, had already built the contractual machinery to convert the resulting enthusiasm into signed revenue and permanent assets. 7. Discussion 7.1 The rational counter argument, taken seriously The strongest objection to everything above is that none of it is bias. It is rational updating. The objection runs as follows. Messi is not merely a good player. He is a global commercial property with an audience of hundreds of millions. When such a property joins a club, the club's expected future cash flows genuinely rise: ticket revenue rises, merchandise revenue rises, sponsorship revenue rises, subscription revenue rises, and international commercial opportunities open that did not exist before. Moreover, the club acquired a genuine competitive asset and proceeded to win, taking its first trophy within weeks and eventually the league championship. A valuation that doubles in response to a genuine doubling of revenue and a genuine change in competitive status is not a #cognitive_bias. It is arithmetic. This objection is largely correct, and any honest analysis must concede it. Much of the increase in Inter Miami's value is real, earned, and defensible. The behavioural claim in this article is not that the increase was illusory. It is narrower and, I think, more interesting: that the timing, the magnitude, the distribution, and the extension of the revaluation to unobservable attributes cannot be explained by fundamentals alone. Four pieces of discriminating evidence support this. First, timing. The resale market moved by an order of magnitude within weeks of an announcement, before a match had been played. Rational repricing on realised fundamentals cannot move before the fundamentals exist. Only expectations can, and expectations are exactly where salience operates. Second, distribution. If the arrival had rationally revalued the league, franchise values across the league would have risen together, because clubs share central media revenue and because a rising league lifts the option value of every seat at the table. Instead, the increase concentrated overwhelmingly on one club, while the bottom of the league rose by roughly 2 percent. Bias is bounded by the object of attention. Fundamentals are not. Third, extension to the unobservable. Fundamentals can justify a revaluation of revenue. They cannot justify the revaluation of managerial competence, organisational culture, branding sophistication, and long term strategic position, none of which were independently tested and all of which were retrospectively upgraded. That is the #halo_effect operating on exactly the ambiguous, slow to verify attributes that Kahneman, Sibony and Sunstein (2021) identify as most vulnerable. Fourth, the Chicago match. More than sixty thousand people attended a fixture that Messi did not play. Whatever they were buying, it was not the marginal product of a footballer. The correct conclusion is therefore not that the market was irrational. It is that the market was doing two things at once, and that only one of them was arithmetic. A substantial part of the revaluation was earned. A substantial part was borrowed, and the borrowed part is the part that carries risk. 7.2 The engineered nature of the effect A second discussion point concerns intent. Did Inter Miami weaponise these biases, or did it simply get lucky? The honest answer is that the record supports deliberate commercial preparation but not necessarily deliberate psychological theory. There is no evidence that anyone in the organisation was reading Thorndike. There is direct evidence, from the club's own executives, that they wrote sponsorship contracts anticipating the arrival of a player of Messi's stature, that they declined deals which refused those clauses, and that they timed expiries to coincide with the expected peak. That is not luck. That is a firm that understood it was buying an attention shock and built the collection infrastructure in advance. This distinction matters for teaching. Students frequently conclude from this case that the lesson is to sign a superstar. That is the wrong lesson, and it is unaffordable for almost every organisation. The transferable lesson is structural: if you anticipate a period of abnormal attention, whatever its source, build the contracts, the pricing, and the capital projects that will convert that attention into durable value before the attention arrives, because you will not have time to build them afterwards and you will have no leverage once it has passed. 7.3 The halo runs both ways The most serious implication of the framework is that the mechanism is symmetric. Thorndike's original finding was that a global impression contaminates specific ratings. He did not restrict the finding to positive impressions. The #horn_effect, the negative mirror of the halo, is equally well documented, and Rosenzweig's business cases are largely stories of firms that were described as visionary while performing well and as dysfunctional, using the same underlying facts, once performance turned. Inter Miami's valuation therefore contains an embedded exposure. A meaningful portion of the value rests on the perception that this is a world class organisation, and that perception was established by association with a player who will, at some point, no longer play. When he stops, the same contamination effect will operate in reverse unless the club has by then generated independent evidence of quality. The retrospective reinterpretation that made the stadium visionary can just as easily make it overbuilt. The narrative that made the ownership group audacious can just as easily make it reckless. Nothing about the club will need to change for this to happen. Only the global impression will. This is #key_person_risk, but of an unusual kind. Ordinary key person risk is the loss of a productive input. Here the input is partly productive and partly perceptual, and the perceptual component is the one that is capitalised into the multiple. 7.4 Observable indicators of a durable revaluation The framework yields a testable set of indicators that would distinguish a club whose value has become structurally independent of its star from one whose value is still borrowed. Analysts and students can apply these to Inter Miami, and to any comparable case. The first indicator is the composition of revenue. If the share of revenue arising from long dated contracts, stadium operations, naming rights, academy transfers, and non matchday events rises relative to the share arising from ticket sales and merchandise tied to one player, the value is becoming structural. The second is attendance and pricing in matches the star does not play. If demand collapses when he is rested or injured, the club is selling the player. If it holds, the club has built an audience. The third is the behaviour of sponsors at renewal. The decisive test is not the deals signed at the peak. It is the deals renewed after his departure, and at what price relative to the peak. The fourth is the geography of the fan base. Attention that converts into local season ticket holders is durable. Attention that converts into international social media followers who never buy anything is not. The fifth is competitive performance without him. A club that continues to win has generated an independent quality signal and no longer needs a borrowed one. 7.5 Comparative context The case is not unique in kind, only in degree. David Beckham's move to the LA Galaxy in 2007 produced a measurable effect on ticket sales (Lawson, Sheehan and Stephenson, 2008), but the media environment of that era could not concentrate global attention in a single product, and the effect on franchise value was modest by comparison. Cristiano Ronaldo's move to the Saudi Pro League produced attendance effects that Schreyer and Singleton (2025) were able to identify, but the league's commercial architecture, and its capacity to convert attention into privately captured franchise value, differs sharply. Caitlin Clark's effect on Women's National Basketball Association attendance, estimated by Gnagey and Koford (2026), exceeds the estimated Jordan effect and is arguably the closest current analogue in structure, although the value capture question there is complicated by league level ownership. What distinguishes Inter Miami is the alignment of four conditions: a maximally uncontested quality signal, a maximally distinctive visual identity, a single global distribution channel, and a private franchise structure in which the resulting value accrued to an identifiable owner. Remove any one of these and the effect weakens substantially. This is the practical boundary condition of the framework, and it explains why the case has proved so difficult for other clubs and leagues to imitate. 8. Implications 8.1 For sport management and club executives The case suggests that the acquisition of a star should be evaluated not as a playing decision with commercial side effects but as a distribution decision with playing side effects. The relevant question at the point of signing is not only what the player will contribute on the field. It is whether the organisation possesses the commercial architecture to collect the attention he will generate: escalator clauses, staggered expiries, dynamic pricing, capacity that can be expanded, a merchandising supply chain that can absorb a demand shock, and capital projects ready to be funded. An organisation without that architecture will generate the attention and watch other parties capture the value, which is roughly what happened to some of Inter Miami's opponents, who hosted enormous crowds and collected a single afternoon of gate revenue while the visiting club collected a permanent revaluation. 8.2 For investors and valuation analysts The case is a warning about the composition of a valuation. Where an asset trades rarely, in a thin market, on the basis of published estimates rather than observed prices, and where the attributes that justify a premium multiple are unobservable, the #halo_effect is not an exotic risk. It is the default condition. Practical mitigation follows directly from the halo literature. Decompose the judgment: rate the club's stadium economics, its management, its academy, and its media position separately, and force each rating to cite evidence that does not mention the star. Kahneman, Sibony and Sunstein (2021) call this structured judgment, and it is designed precisely to prevent a global impression from leaking into specific assessments. Ask what the same analyst would have written about the same organisation eighteen months earlier. If the facts are identical and the language has changed, the change is in the analyst. 8.3 For marketing practice For marketers, the case demonstrates that the #frequency_illusion is an achievable objective rather than an accidental phenomenon, provided the brand can supply three inputs: a perceptual tag that is distinctive enough to be recognised without reading, a channel in which the tag can be encountered repeatedly, and a mechanism for placing the tag inside content categories that the audience did not choose to enter. Pink, a global streaming product, and celebrity attendance supplied all three. Most brands cannot buy Messi. Most brands can build a tag, choose a channel, and buy their way into an adjacent category. The ethical limit is worth stating. A manufactured #frequency_illusion is a device for making people notice. It is not, in itself, deceptive. It becomes deceptive when the halo it produces is deliberately used to represent unverified organisational qualities as verified ones, particularly to counterparties who are pricing long dated contracts. The line between vivid marketing and misrepresentation is the line between making people look and telling them what they have seen. 8.4 For students The pedagogical value of the case lies in the discipline of separating three questions that are usually merged: what changed, what was noticed, and what was believed. In this case, one input changed. A vast amount was noticed. And a great deal more was believed than was ever demonstrated. The gap between the second and third of those is where the #cognitive_bias lives, and learning to locate that gap is a transferable analytical skill, applicable to a technology firm with a charismatic founder, a fund with one exceptional year, or a university with one famous professor. 9. Limitations and Future Research The limitations set out in Section 5.4 constrain the strength of the conclusions. Published valuations are estimates. The design is a single case. Bias is inferred, not observed. Four lines of future research follow naturally. The first is an event study of announced sponsorship deals involving clubs that sign globally recognised athletes, testing whether the observed premium exceeds what the expected incremental audience can justify. This would allow the halo component to be estimated rather than inferred. The second is an experimental test of the transfer mechanism. Participants could be asked to evaluate the management, strategy, and brand strength of a fictional club under conditions that vary only the presence of an elite player. If the ratings of unrelated attributes shift, the transfer is confirmed under controlled conditions. The third is a longitudinal study of the post star period. The framework predicts a reverse halo, and its magnitude should be a function of how much of the attention shock was converted into contracts and assets. Inter Miami will provide this data in due course, and the prediction is falsifiable. The fourth is comparative. Applying the salience, transfer, capitalisation model to the Saudi Pro League, to the Women's National Basketball Association, and to earlier cases such as Beckham in 2007 would establish the boundary conditions under which engineered salience produces durable value rather than a temporary spike. 10. Conclusion The revaluation of Inter Miami CF is usually told as a story about a great player who made a small club rich. That story is true and incomplete. The more precise account is that a club with a distinctive visual identity, sitting inside a league with a single global distribution channel, acquired the least ambiguous quality signal available in world sport, and thereby triggered two well documented cognitive mechanisms in sequence. The first, the #frequency_illusion, made the world notice. It did so through contrast, repetition, and the importation of audiences from outside the sport, and its financial signature was a resale market that rose by an order of magnitude before a competitive match had been played. The second, the #halo_effect, made the world believe. It transferred the uncontested excellence of an individual to an organisation whose actual capabilities remained exactly as unverified as they had been the previous season, and its financial signature was a class of global sponsor and a valuation multiple appropriate to a club with a century of pedigree rather than three seasons of results. What separates this case from a simple story about bias is that the organisation appears to have prepared for the moment. The escalator clauses, the staggered contract expiries, the expanded capacity, and the stadium project were the machinery through which a temporary shock to perception was converted into contracted revenue and permanent assets. Value that is borrowed must be converted before it is recalled, and Inter Miami converted quickly. The unresolved question is the one the framework insists upon. A valuation constructed partly on perception is exposed to the reversal of that perception, and the same contamination that made every previously ordinary feature of the club look visionary will, when the player is gone, be equally capable of making them look ordinary again. Whether Inter Miami emerges as a structurally premium franchise or as a cautionary example of a halo that faded will not be determined by what Messi did. It will be determined by how much of the attention he generated was converted, while it lasted, into things that do not depend on him. #Messi_Effect #Inter_Miami #Major_League_Soccer #halo_effect #frequency_illusion #red_car_effect #cognitive_bias #behavioural_economics #sports_economics #franchise_valuation #superstar_economics #sport_marketing #brand_equity #attention_economy #salience_theory References Adler, M. (1985). Stardom and talent. American Economic Review, 75(1), 208-212. Bordalo, P., Gennaioli, N., and Shleifer, A. (2022). Salience. 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International executives often report that a single, well-placed act of cultural respect changes the temperature of a negotiation room within minutes. This article asks why that happens, and whether the effect can be trained rather than left to luck. It builds a conceptual framework that links three bodies of work that are usually kept apart: #cultural_intelligence research in international management, the #frequency_illusion in attention science (popularly called the Red Car Effect), and the #Halo_Effect in social judgment. The argument is simple. Executives who deliberately prime themselves to notice #cultural_nuance begin to perceive signals that were previously filtered out of awareness. Acting on one of those signals, visibly and competently, produces a strong positive first impression. That impression then spreads across unrelated judgments, so host partners infer that the visitor is also skilled, reliable, and honest in matters they have not yet observed. The article develops a four-stage model, labelled here the Notice, Act, Halo, and Verify sequence, and states a set of propositions that future empirical work can test. It also treats the darker side of the mechanism seriously: a halo built on #protocol rather than substance is fragile, can shade into #tokenism, and can mislead the host as easily as it can reassure them. The paper closes with a training design for #executive_education, a set of ethical guardrails, and a research agenda. The contribution is integrative rather than empirical, and the framework is offered as a testable proposition set, not as an established finding. Keywords: cultural intelligence; frequency illusion; halo effect; cross-cultural negotiation; trust formation; cognitive bias; international business; impression management 1. Introduction 1.1 The problem in practice A regional director flies from Frankfurt to Jakarta to close a distribution agreement. The commercial terms are settled in advance. The technical annexes are agreed. On paper, the meeting is a formality. Yet the deal stalls for four months, and no one on the host side can explain exactly why. Six weeks later a second executive from the same firm travels to the same office. She accepts the offered drink before speaking about business, she uses both hands when receiving a card, she addresses the most senior person present first and by the correct honorific, and she does not fill the pauses in conversation. She has not changed the price. She has not changed the contract. The agreement is signed within three weeks. Practitioners tell versions of this story constantly, and business schools repeat it as folklore. Very little of the folklore is explained. What exactly did the second executive do that the first did not, and what happened inside the minds of the host partners when she did it? This paper argues that two well documented cognitive mechanisms, operating in sequence, provide a plausible answer, and that the sequence can be trained. 1.2 The two mechanisms The first mechanism concerns #attention. Human beings cannot process everything available to their senses, so the perceptual system filters aggressively. What survives the filter is not random. It reflects current goals, physical #salience, and the history of what the individual has selected in the past (Anderson et al., 2021). One consequence, familiar to almost everyone, is that a concept that has just entered awareness suddenly appears everywhere. You decide to buy a particular car, and the roads seem full of it. The cars were always there. Your #perception changed, not the world. Psychologists call this the #frequency_illusion or the Baader-Meinhof phenomenon; practitioners call it the #Red_Car_Effect. It is generally attributed to the interaction of #selective_attention and #confirmation_bias, and recent experimental work confirms that attending selectively to a stimulus alters what people subsequently prefer and choose (Egger and Florack, 2022). The second mechanism concerns #impression_formation. When people form a judgment about a person on one dimension, that judgment leaks into unrelated dimensions. Someone judged positively on a visible attribute is also assumed to be more capable, more stable, more responsible, and more trustworthy, even when no evidence has been offered on those points. This is the #Halo_Effect. A study across forty five countries and eleven world regions found that attractive faces were rated as more confident, more emotionally stable, more intelligent, more responsible, more sociable, and more trustworthy, which suggests that the halo is not a Western peculiarity but a broadly human pattern of #social_judgment (Batres and Shiramizu, 2023). A cross-cultural comparison of German and Japanese observers reached broadly similar conclusions, finding no significant cross-cultural differences in the halo attached to facial appearance, though it did detect small variations in which attributes were weighted (Kordsmeyer et al., 2024). 1.3 The proposed link The link this article proposes is causal and sequential. #Applied_cultural_intelligence is, in part, the deliberate manufacture of a #Red_Car_Effect for cultural signals. Executives train themselves to notice the specific cues that matter in a given market: the seating order, the timing of the first substantive proposal, the meaning of a smile that is not a smile, the difference between a polite yes and a committed yes. Once primed, those cues stop being background noise and become foreground data. Noticing is not enough. The executive must then act on one cue in a way that is visible to the host and demonstrably difficult. Difficulty matters, because an act that costs nothing signals nothing. When the act lands, it functions as a #costly_signal of respect and preparation, and it generates a halo. The host partners, who have limited information and limited time, generalise from what they can see to what they cannot. They infer #competence in areas they have not yet tested, and they extend provisional #trust ahead of the evidence. That inference may turn out to be correct. It may also be badly wrong. The framework therefore includes a fourth stage, verification, in which the initial halo is either converted into evidence-based trust or is exposed as hollow. Ignoring this stage would make the article a manual for manipulation rather than a piece of research. 1.4 Research questions The article addresses four questions. How does trained attention to #cultural_nuance alter what an international executive perceives in a negotiation setting? Through what mechanism does a single visible act of cultural respect influence broader judgments of #credibility? What conditions strengthen, weaken, or reverse that influence? What are the ethical and practical limits of designing #training_design around these effects? 1.5 Contribution Three contributions are claimed. First, the paper integrates attention research, social judgment research, and the #cultural_intelligence literature, three streams that rarely cite one another. Second, it converts an anecdotal practitioner belief into a specified model with stated propositions, which makes it falsifiable. Third, it takes the ethics seriously, treating the halo as a hazard for the host as much as an asset for the visitor. The article is conceptual. No new data are presented, and the propositions are offered for testing rather than as demonstrated results. 2. Literature Review 2.1 Cultural intelligence as a capability Cultural intelligence, usually abbreviated CQ, refers to an individual capability to function effectively in culturally diverse settings. It is conventionally decomposed into four facets. #Metacognitive_CQ is awareness and control of one's own cultural thinking, including the ability to plan for an interaction, monitor assumptions during it, and revise them afterwards. #Cognitive_CQ is knowledge of cultural systems, norms, and practices. #Motivational_CQ is the drive and confidence to engage across difference. #Behavioral_CQ is the capacity to adjust verbal and nonverbal conduct appropriately. A meta-analysis of seventy studies examined the relationship between CQ and six work-related outcomes and found that the facets have incremental predictive validity beyond personality traits and other established predictors, and that they mediate the relationship between personality and work outcomes (Schlaegel, Richter and Taras, 2021). One finding in that synthesis is directly relevant here. #Motivational_CQ emerged as the strongest predictor of both job satisfaction and job performance, while #cognitive_CQ was the weakest. In plain terms, wanting to engage across cultural difference appears to matter more than possessing a stock of cultural facts. This is a corrective to the way #cross_cultural_competence is often taught, which loads heavily on facts and lightly on motivation and practice. The construct has been mapped and remapped. A review of half a century of measurement in this area examined how theoretical constructs and empirical measures have drifted apart, and called for tighter alignment between what researchers claim to measure and what their instruments actually capture (Richter, Schlaegel, Taras, Alon and Bird, 2023). Related work has argued that CQ is best understood through an identity lens, with cross-cultural experience shaping CQ only when it is processed through changes in how the individual sees themselves (Pidduck, Shaffer, Zhang, Cheung and Yunlu, 2022). The capability has also been extended from individuals to organisations, with a proposal that firms themselves can hold organisational CQ, embedded in systems, norms, and routines rather than in any single manager (Livermore, Van Dyne and Ang, 2022). Two points from this literature anchor the present argument. First, CQ is a capability, not a trait, which means it is trainable. Second, its most predictive facets are the ones concerned with #noticing and #adjusting in the moment, rather than with pre-loaded knowledge. Both points fit an attention-based reading of what culturally intelligent people actually do. 2.2 The frequency illusion and the architecture of attention For most of the last century, attention was described as a contest between two forces. Salient stimuli grabbed attention from the bottom up. Goals directed attention from the top down. That dichotomy has been replaced. Contemporary work describes a trichotomy in which current goals, physical salience, and selection history jointly determine what reaches awareness (Anderson et al., 2021). #Selection_history is the accumulated record of what an individual has attended to and been rewarded for attending to. Some of it is learned slowly. Some of it is highly transient. All of it biases what will be seen next. This is the machinery underneath the #frequency_illusion. Once a concept has been made available and given some value, the attentional system begins prioritising instances of it. The standard explanation combines #selective_attention, which brings the newly relevant category to the front of the queue, with #confirmation_bias, which counts the hits and ignores the misses. The result is a subjective sense that the thing is suddenly everywhere. Experimental work has begun to specify the downstream consequences. Selective attention does not merely change what people notice. It changes what they subsequently prefer and choose, and the effect operates through mechanisms that can be isolated in the laboratory (Egger and Florack, 2022). That finding is important for the present argument, because it means the Red Car Effect is not a curiosity of perception with no behavioural consequence. Attention shapes preference, and preference shapes decisions. Two clarifications are needed, because the practitioner literature on this topic is loose. First, the frequency illusion is normally described as an error. It produces a mistaken belief about how often something occurs. That is a real risk, and section 8 returns to it. But the underlying attentional shift is not itself an error. Attending to previously filtered signals can be accurate and useful. The distortion enters when the perceiver also concludes that the base rate has changed, or that every instance of the noticed pattern is meaningful. A negotiator who suddenly notices indirect refusals everywhere may be perceiving accurately for the first time, or may be over-reading ordinary hesitation. The framework must be able to tell those apart. Second, deliberate priming is not the same as spontaneous illusion. The classic Red Car Effect is accidental. What the #cultural_intelligence practitioner does is intentional: they choose which categories to install in advance, and they choose them on the basis of evidence about the market in question. The mechanism is the same; the control is different. This paper uses the term #primed_noticing for the intentional version to keep the two apart. 2.3 The halo effect and the economics of thin information The halo effect describes the tendency for an evaluation on one salient dimension to colour evaluations on other, logically independent dimensions. The evaluator is rarely aware that this is happening, which is what distinguishes a #cognitive_bias from a reasoned inference. The cross-cultural evidence is now reasonably strong. The forty five country study cited earlier found the attractiveness halo across all eleven world regions studied, with attractive faces rated higher on confidence, emotional stability, intelligence, responsibility, sociability, and trustworthiness (Batres and Shiramizu, 2023). A German and Japanese comparison found the effect present in both samples, with only small and non-significant cross-cultural differences in face perception, though the relative weighting of dominance and prosociality varied in a direction consistent with individualism and collectivism (Kordsmeyer et al., 2024). The reasonable summary is that the halo travels, while the currency it trades in may vary. Why does the halo exist at all? The most economical explanation is informational. Social judgment is made under severe constraints of time and data. A systematic review of the #stereotype_content model, covering nearly a thousand articles, confirms that two dimensions dominate impression formation across contexts: #warmth and #competence (Luna Cortes, 2024). When an observer has almost no information about a stranger, any signal that loads clearly on one of those dimensions will do a great deal of work, because there is nothing else to work with. The halo is not stupidity. It is inference under scarcity. This matters for the cross-border case in a specific way. A visiting executive arrives with almost no locally verifiable track record. The host cannot easily check their reputation, cannot call a mutual acquaintance, and often cannot evaluate their technical claims. Informational scarcity is at its maximum. That is precisely the condition under which halo effects are strongest, and it explains why first impressions carry unusual weight in international dealings compared with domestic ones. 2.4 Trust formation across borders Trust in international business settings has to be established faster and on thinner evidence than in domestic settings. The parties may meet only a handful of times before large commitments are made. Legal enforcement across jurisdictions is slow and expensive, so the parties rely more heavily on relational assurance than a purely contractual account would predict. Research on #global_virtual_teams has shown how quickly this becomes acute when physical presence is removed. Cultural intelligence has been found to shape communication accommodation within such teams, which in turn affects interpersonal process effectiveness (Presbitero, 2021). Cultural and emotional intelligence have been examined jointly as predictors of conflict occurrence and team performance in distributed settings (Davaei, Gunkel, Veglio and Taras, 2022), and motivational configurations of CQ have been linked to social integration and performance (Richter, Martin, Hansen, Taras and Alon, 2021). A broader review of the role of different intelligences in teams reaches similar conclusions about the centrality of cultural capability in mixed groups (Davaei and Gunkel, 2024). A communication-focused review of global virtual teams notes that language proficiency and cultural intelligence interact, with CQ acting as a protective factor when linguistic fluency is limited (Liu, 2025). The expatriate literature adds a further piece. Cultural intelligence has been linked to thriving at work among assigned expatriates, with local embeddedness and relational attachment carrying part of the effect (Gyensare, Jain, Asante, Adomako, Ofori and Hayford, 2025). Embeddedness is, in effect, accumulated evidence. It is what replaces the halo once the halo has done its work. 2.5 The gap Each literature is healthy on its own terms, and each is largely silent about the others. The #cultural_intelligence literature describes what culturally intelligent people can do, but is thin on the perceptual mechanism by which they come to see what others miss. Attention research explains the mechanism precisely, but almost never applies it to organisational or cross-cultural settings. Social judgment research documents the halo in detail, mostly through studies of faces and static stimuli, and rarely asks whether a deliberate behavioural act can generate a halo as reliably as an unearned physical attribute does. Negotiation research knows that first impressions matter, but tends to treat them as noise to be controlled rather than as a mechanism to be understood. The gap, then, is a missing sequence. Nobody has specified how trained attention leads to a specific act, how that act generates a halo, and what happens to the halo afterwards. Section 3 offers such a specification. 3. Theoretical Framework: The Notice, Act, Halo, Verify Sequence 3.1 Overview The framework has four stages. Each is a distinct cognitive or behavioural event, occurring in a different mind or at a different moment. Stage 1, Notice. The visiting executive, primed in advance, perceives cultural signals that would otherwise be filtered out. This happens inside the visitor's head, before and during the encounter. Stage 2, Act. The executive performs one visible, effortful act of cultural respect that responds correctly to a noticed signal. This happens in the room and is observable. Stage 3, Halo. The host partners generalise from the act to unobserved attributes, inferring competence, reliability, and ethical conduct. This happens inside the hosts' heads and is largely outside their awareness. Stage 4, Verify. Over subsequent interactions, the initial inference is tested against evidence. The halo either converts into durable trust or collapses, sometimes with a penalty. The stages are sequential but not automatic. Each can fail, and the failure modes differ. Sections 3.2 to 3.5 set out each stage and its associated propositions. 3.2 Stage 1: Notice The behavioural target at this stage is #cue_recognition. The relevant cues in most business cultures fall into recognisable families: greeting and address, spatial arrangement and seating, turn-taking and interruption, the handling of #silence, the sequencing of relationship talk and business talk, gift and hospitality conventions, the treatment of #hierarchy and the routing of questions, the meaning of indirect refusal, and the tempo of decisions. The cognitive claim is that these cues are not invisible to the untrained executive. They are present in the sensory field and are being discarded by the attentional filter, because nothing in the executive's #selection_history has marked them as worth prioritising (Anderson et al., 2021). Training changes the priority assignment. Once the category has been installed, instances of it start to pop out. The subjective experience is exactly the Red Car experience: the executive reports that the cues are suddenly everywhere, and often assumes wrongly that the hosts have started behaving differently. Proposition 1. Structured pre-encounter priming on a small number of specific, market-relevant cultural cues increases the number of such cues an executive detects during a live cross-border encounter, relative to general cultural awareness training of equivalent duration. Proposition 2. The relationship between priming and detection is stronger for #behavioral cues that are frequent and low in physical salience, such as pauses, seating, and turn-taking, than for cues that are rare or already salient, such as a formal gift exchange. Proposition 3. Detection gains are subject to a distortion penalty. Primed executives will over-report the frequency of primed cues relative to objective coding of the same interaction, consistent with the #frequency_illusion. Proposition 3 deserves emphasis. It predicts that the very training that improves perception also introduces a measurable bias, and it makes the framework falsifiable in an uncomfortable direction. A model that only predicted good news would be less useful. 3.3 Stage 2: Act Noticing without acting produces nothing observable. The host cannot see the executive's improved perception. They can only see behaviour. Not all acts are equal. Drawing on the logic of signalling, the framework proposes that an act of cultural respect generates a halo in proportion to four properties. Visibility. The act must be perceived by the people whose judgment matters, including the senior decision maker, who is often not the person the visitor has been talking to. Difficulty. The act must be recognisably hard for an outsider. Pronouncing a complex name correctly, following a multi-step #ritual without prompting, or using an appropriate honorific in a language one does not otherwise speak all qualify. Difficulty is what converts the act into a #costly_signal, because an act that anyone could produce carries no information about the actor. Accuracy. The act must be correct. A half-remembered ritual performed clumsily is worse than no ritual, because it signals effort without competence, which is the least flattering combination available. Non-instrumentality. The act must not look like a sales technique. If the host reads the gesture as a tool aimed at extracting concessions, the signal inverts and reads as #manipulation. Proposition 4. Acts of cultural respect that are high in visibility, difficulty, accuracy, and non-instrumentality produce stronger positive evaluations of the actor than acts that are high on fewer of these properties. Proposition 5. Difficulty and accuracy interact. High difficulty with low accuracy produces a worse evaluation than low difficulty with high accuracy, because failure at a difficult, publicly attempted task is highly diagnostic. Proposition 5 is the reason this framework does not recommend that executives attempt everything. The advice that follows from it is narrow: master one demanding thing completely rather than attempting five things approximately. 3.4 Stage 3: Halo Stage 3 relocates the action to the hosts' minds. Having observed a correct, difficult, respectful act, they must decide what it means. The inference chain runs roughly as follows. This person did something outsiders almost never get right. Getting it right required preparation and attention that most visitors do not invest. Someone who invests that much in a detail that does not directly serve their commercial interest is probably serious, probably prepared, and probably respects us. People who are serious, prepared, and respectful in one domain are usually so in others. The first three steps of that chain are defensible. The fourth is the halo, and it is not defensible, though it is nearly universal. It is the generalisation from an observed attribute to unobserved attributes, and it is exactly what the #stereotype_content research would predict under conditions of thin information: the act loads simultaneously on #warmth, because it reads as respect, and on #competence, because it reads as difficult and correctly executed, and those two dimensions are what impression formation runs on (Luna Cortes, 2024). Proposition 6. A single visible, difficult, accurate act of cultural respect increases host partners' ratings of the visitor's general competence, reliability, and ethicality on dimensions unrelated to the act. Proposition 7. The halo is strongest when host partners have the least independent information about the visitor, and it weakens as verifiable information about the visitor accumulates. Proposition 8. The halo produced by an act of cultural respect loads on both warmth and competence, whereas a halo produced by a display of technical skill alone loads primarily on competence. Consequently, cultural acts have a larger effect on #trust than technical displays of equivalent impressiveness. Proposition 8 is the sharpest empirical claim in the paper, and the easiest to test. It predicts that a visiting engineer who solves a difficult technical problem in front of the client and a visiting engineer who performs a difficult cultural protocol correctly will be judged as similarly competent, but the second will be judged as substantially more trustworthy. If that comparison fails, a central plank of the framework fails with it. 3.5 Stage 4: Verify The halo is a loan, not a payment. It advances credibility on the strength of one observation, and the loan is called in. Three outcomes are possible. Conversion. Subsequent behaviour confirms the inference. The visitor is in fact prepared, reliable, and honest. The halo is replaced by evidence-based trust, and the initial impression has simply accelerated a relationship that was going to work anyway. This is the desirable case and, in the framework, the only defensible objective of the entire sequence. Decay. Subsequent behaviour is neutral. The halo fades without incident. Nothing is gained and little is lost. Reversal. Subsequent behaviour contradicts the inference. Here the framework predicts an overshoot. The host partner does not merely revise the estimate downward to a neutral prior; they revise it below neutral, because they now believe they were deliberately deceived. The very features that made the act effective, its difficulty and apparent sincerity, become evidence of calculated impression management. Proposition 9. Where an initial cultural halo is followed by disconfirming conduct, the resulting decline in trust is greater than the decline that would follow the same disconfirming conduct in the absence of an initial halo. This is the #halo_decay penalty, and it is the single most important managerial finding in the paper. It converts an apparently costless tactic into a leveraged bet. The executive who performs the protocol perfectly and then misses three delivery deadlines is in a worse position than the executive who never performed the protocol at all. 3.6 Moderators Four moderators are proposed. Cultural tightness. In settings where norms are strong and deviation is sanctioned, protocol carries more information, so both the halo and the reversal penalty should be larger. In looser settings, protocol carries less information and the effects should attenuate. Relational orientation. Where business relationships are expected to precede transactions, cultural acts should be weighted more heavily relative to technical displays, strengthening Proposition 8. Perceived instrumentality of the setting. In a formal competitive tender, where every participant is understood to be performing, cultural acts are discounted as strategy. In an informal or hospitality setting, they are read as sincere. Observer's own CQ. Host partners who are themselves culturally sophisticated should be less susceptible to the halo, because they possess more diagnostic categories and can separate protocol competence from business competence. This yields a counterintuitive prediction: the tactic works least well on the most internationally experienced counterparts. 3.7 Summary of the framework The sequence can be stated in one sentence. Trained #attention makes a cue visible; a difficult and accurate response to that cue makes the actor visible; the actor's visibility on warmth and competence makes them provisionally trustworthy; and provisional trust is either earned out or paid back with interest. 4. Methodology 4.1 Approach This is a conceptual paper. Its method is integrative literature synthesis, in which theory from separate fields is combined to produce a new explanatory structure and a testable proposition set. Integrative synthesis is appropriate when the phenomenon of interest is well attested in practice but has no unified theoretical account, which is the case here. 4.2 Literature selection Sources were drawn from three streams. The first was #cultural_intelligence and international management, prioritising meta-analyses, systematic reviews, and empirical work published in established international business journals. The second was attention and cognitive bias research, prioritising review articles that summarise the current state of the attentional control debate and experimental work on selective attention and choice. The third was social judgment research, prioritising cross-cultural evidence on the halo and systematic review evidence on impression formation. Preference was given to work published within the last five years, on the grounds that both the CQ measurement debate and the attentional control debate have moved substantially in that period. Older foundational work is acknowledged in the text where necessary but is not relied on for the central claims. 4.3 Framework construction The framework was constructed by identifying the point at which each literature stops. Attention research explains how a cue becomes visible but does not ask what the perceiver then does. Signalling logic explains what makes an act informative but does not explain how the actor came to know which act to perform. Social judgment research explains how observers generalise from a signal but treats the signal as given. The proposed sequence connects these endpoints. 4.4 Limits of the method Conceptual papers do not test anything. Every proposition here is a hypothesis. Where the paper says that a mechanism operates, it means that existing evidence makes the mechanism plausible, not that the mechanism has been demonstrated in the cross-border negotiation setting specifically. Section 10 sets out how the framework could be tested, and section 11 restates the limitation. 5. Analysis: How the Mechanisms Interact 5.1 Why noticing is the bottleneck Most #cross_cultural_competence training front-loads knowledge. Executives are given country briefings, dimension scores, and lists of dos and don'ts. The meta-analytic evidence suggests this is the least productive investment available, since #cognitive_CQ was the weakest predictor of both job satisfaction and performance among the four facets, while #motivational_CQ was the strongest (Schlaegel, Richter and Taras, 2021). The framework offers an explanation for that pattern. Knowledge without attention is inert. An executive can know that indirect refusal is common in a given market and still fail to notice a specific indirect refusal delivered to their face, because the knowledge sits in memory while the cue passes through a perceptual filter that has never been told to look for it. Priming and knowledge are not the same operation. Knowledge answers what does this mean. Priming determines whether the thing is seen at all. This reframes the training problem. The task is not to teach executives more about a culture. It is to change what their attentional system prioritises during live interaction. That is a #deliberate_practice problem, not a lecture problem. 5.2 The selectivity trade-off Priming has a cost, and the cost is structural rather than incidental. Attention is a limited resource. Prioritising one category necessarily de-prioritises others. An executive primed to detect indirect refusal will detect indirect refusal, and may correspondingly miss a shift in the counterpart's commercial position that a less primed observer would have caught. This produces a design constraint that most practitioner advice ignores. Priming must be narrow. Three to five cues, chosen for their diagnostic value in the specific market and the specific deal, will outperform a list of twenty. The list of twenty produces either no priming at all, because nothing is prioritised, or a scattered attention that catches everything and interprets nothing. Design principle 1. Prime few cues, chosen for diagnosticity, not for coverage. 5.3 Why one act beats many The signalling analysis in section 3.3 has a direct practical consequence, and it runs against intuition. The intuitive strategy is breadth: learn many customs, perform as many as possible, accumulate credit. The framework predicts that this is inferior. Breadth reduces average accuracy, and inaccuracy in a difficult, publicly attempted act is highly diagnostic in the wrong direction (Proposition 5). Breadth also reduces visibility, because a series of small correct gestures does not produce a single memorable event, and memory is what the halo is built on. Finally, breadth increases the appearance of instrumentality, because an executive who is performing constantly looks like an executive who is performing. One difficult thing, done exactly right, at the right moment, in front of the right person, dominates. Design principle 2. Depth over breadth. Master one demanding protocol completely. 5.4 Where the halo comes from and what it costs the host It is worth stating plainly that the halo is a #bias, and that in stage 3 the person being biased is the host, not the visitor. The host is making an inference that is not warranted by the evidence. They are extending trust on the basis of a protocol performance that carries no logical information about delivery capability, financial stability, or contractual good faith. From the host's point of view, the mechanism described in this paper is a vulnerability. Any account of it that treats it purely as a technique for the visitor is incomplete and, in the end, dishonest. Section 8 develops this point, but it belongs in the analysis as well, because it changes what the framework is for. The purpose of the sequence, correctly understood, is not to generate unearned trust. It is to remove the friction that prevents a genuinely competent and honest partner from being recognised as one. That is a narrower and more defensible purpose, and it has a hard implication: an executive who cannot deliver should not run the sequence. 5.5 The virtual case Distributed and virtual settings compress the available signal. Much of the cue set described in section 3.2, including seating, spatial arrangement, and most nonverbal conduct, either disappears or degrades. What remains is language, timing, turn-taking, and the handling of #silence. The available research suggests the underlying capability still operates. Cultural intelligence has been shown to influence communication accommodation in global virtual teams, which in turn affects interpersonal process effectiveness (Presbitero, 2021), and cultural and emotional intelligence jointly shape conflict and performance in such teams (Davaei, Gunkel, Veglio and Taras, 2022). Motivational configurations of CQ predict social integration and performance in distributed groups (Richter, Martin, Hansen, Taras and Alon, 2021), and CQ appears to buffer the effects of limited language proficiency (Liu, 2025). The framework's prediction for virtual settings is therefore specific rather than pessimistic. The channel for stage 2 shifts from physical protocol to linguistic and temporal protocol. Correct pronunciation of names, scheduling that absorbs the cost of time zone asymmetry rather than imposing it, appropriate handling of turn-taking in a group where some participants are speaking a second language, and correct use of written formalities become the difficult, visible acts. The halo mechanism itself is unchanged. Design principle 3. In virtual settings, relocate the signal to language, timing, and written form. 5.6 When the sequence should not be run Three conditions make the sequence inadvisable. The first is inability to deliver. If the visitor's firm cannot meet the commitments the deal implies, generating a halo is straightforwardly harmful to the host and, by Proposition 9, eventually harmful to the visitor. The second is high counterpart sophistication. Against a highly experienced international counterpart with strong CQ of their own, protocol competence is expected and therefore uninformative. It will not generate a halo, and a conspicuous attempt to generate one may be read as naive. The third is a setting that is explicitly competitive and performative, such as a formal tender, where every party is understood to be signalling and signals are consequently discounted. 6. Applied Framework: A Training Design This section converts the model into a training protocol. It is offered as a design specification for #executive_education, not as a validated curriculum, and its components are stated in a form that would allow them to be evaluated. 6.1 Phase 1: Cue mapping Objective. Identify three to five diagnostic cues for the specific market and deal type. Method. Cue mapping should be done from primary sources: structured interviews with people who have negotiated in that market, recorded and transcribed; observation of prior meetings where available; and debriefs with local staff. Country dimension scores may inform the process but should not drive it, because national averages predict individuals poorly and the cues that matter are usually local, sectoral, and firm-specific rather than national. Output. A written cue sheet, no longer than one page, listing each cue, what it looks like, what it usually means, and what an appropriate response is. Common failure. Producing a twenty item list. See design principle 1. 6.2 Phase 2: Priming Objective. Install the cues in the attentional system so that they are detected in real time rather than recognised in retrospect. Method. Repeated exposure with response. The executive is shown recorded or enacted interactions and asked to identify instances of the target cues, with immediate feedback on hits and misses. Exposure without response is insufficient. The literature on selection history suggests that what shapes attentional priority is the history of selecting a stimulus, not the history of being told about it (Anderson et al., 2021). Output. A measurable detection rate. The executive should be able to identify target cues in unfamiliar material at a specified accuracy before proceeding. Common failure. Substituting a briefing for practice. A briefing changes knowledge and does not change #attention. 6.3 Phase 3: Protocol mastery Objective. Achieve full competence in one demanding, visible act. Method. #Deliberate_practice with correction from a native practitioner, continued past the point of apparent competence. The standard is not adequacy. It is that a knowledgeable local observer would not be able to tell that the executive learned it recently. Selection of the act. The act should be difficult, visible to the senior decision maker, appropriate to the specific setting, and not obviously instrumental. Candidate acts include: correct pronunciation and use of names and honorifics; the full sequence of a formal greeting or hospitality ritual; correct behaviour in a hierarchy-sensitive seating or introduction sequence; opening remarks delivered in the local language to a standard that is genuinely fluent rather than phonetically memorised; correct handling of a #gift_giving or hospitality convention including the refusal and acceptance sequence. Common failure. Stopping at the point where the act is recognisable but visibly effortful. Proposition 5 predicts that this is worse than not attempting it. 6.4 Phase 4: Live deployment Objective. Perform the act correctly and once. Method. Timing and audience are as important as execution. The act must occur when the relevant decision maker is present and attending, and it must not be repeated, because repetition converts a signal into a routine and a routine into a performance. Common failure. Announcing the act, explaining it, or drawing attention to it afterwards. Commentary destroys the signal, because a signal that the actor advertises is no longer a costly signal of respect; it is a claim. 6.5 Phase 5: Verification and conversion Objective. Convert the halo into evidence before it decays or reverses. Method. The period immediately after a successful stage 3 is the period of maximum unearned credit, and it should be spent on demonstrable delivery: meeting the first small commitment early, answering the first difficult question completely, and volunteering the first piece of unfavourable information before it is discovered. Volunteering unfavourable information is the most efficient conversion move available, because it is the one behaviour that a purely impression-managing actor would not perform. Common failure. Treating the halo as an achievement rather than a liability. It is a debt with a repayment schedule. 6.6 Measurement A training programme built on this framework should be evaluated on four things, and self-report should not be one of them. Detection rate in unfamiliar material provides a measure of stage 1. Blind expert rating of recorded protocol performance provides a measure of stage 2. Counterpart ratings of competence, reliability, and ethicality on dimensions unrelated to the act, collected shortly after the encounter, provide a measure of stage 3. Objective relationship outcomes over the following year, including cycle time to agreement, renegotiation frequency, and dispute incidence, provide the only measure that matters for stage 4. The reliance on self-report in much CQ research is a known problem, and the misalignment between theoretical constructs and empirical measures has been documented in this literature (Richter, Schlaegel, Taras, Alon and Bird, 2023). A training design that measures its own success by asking participants how culturally intelligent they now feel is measuring confidence, not capability. 7. Illustrative Scenarios The following scenarios are composite and hypothetical. They are constructed to illustrate the mechanisms and the failure modes, and they should not be read as reported cases or as evidence. 7.1 The conversion case A supply chain executive preparing for a first meeting in a market where seniority is signalled subtly identifies three cues: the order in which people are introduced, who answers questions addressed to the group, and the length of pause before a polite disagreement. She practises detecting these until she can identify them reliably in recorded material. In the meeting, she notices that the person she had assumed was junior is the person to whom all questions are quietly routed. She redirects her substantive proposal accordingly, and she addresses him with the correct form of address, which she has practised for two weeks and which most visitors get wrong. The hosts notice. Their subsequent behaviour changes: they volunteer information they had not volunteered before, and they raise an objection they had previously suppressed. In the following month she meets the first delivery commitment three days early and discloses a component sourcing risk that the host had not yet asked about. The halo converts. Trust becomes evidence-based. 7.2 The reversal case A second executive, from a competing firm, has learned the same form of address. He performs it correctly. The initial impression is strong. He then misses two commitments and, when challenged, attributes the delay to the host's own paperwork. The host partners revise their assessment sharply downward, and one of them says privately that the greeting now looks like preparation for a sales performance. The halo reverses, and by Proposition 9 the resulting position is worse than if he had never learned the protocol at all. 7.3 The tokenism case A third executive has memorised a local proverb and deploys it in the opening remarks. The proverb is correct. The pronunciation is approximately right. But it has no relationship to anything under discussion, it is delivered to a room that includes two people who did not grow up in that culture, and the executive follows it by explaining that he has been learning about the culture. The act fails on non-instrumentality and, because he has drawn attention to it, on the implicit rule in section 6.4. The hosts read it as a technique. It generates no halo, and it generates a small amount of #cynicism. 7.4 What the three cases show The difference between the cases is not knowledge. All three executives knew something about the local culture. The differences are in what they noticed, in the accuracy and appropriateness of what they did with it, and in whether they had anything real to convert the resulting credit into. 8. Ethical Considerations 8.1 The core problem The framework describes a method by which one party can obtain trust from another party faster than the evidence justifies. That is, on its face, a description of a manipulation technique, and it would be dishonest to present it otherwise. The defence is not that the halo is harmless. It is that the halo already exists. Host partners generalise from visible signals whether or not visitors are aware of it, and they do so in every market studied (Batres and Shiramizu, 2023; Kordsmeyer et al., 2024). The question is not whether cross-border judgments will be influenced by thin cues. They will. The question is which cues, and whether they favour parties who have prepared and who intend to deliver, or parties who happen to look and sound like the host's existing expectations. Seen this way, the sequence is defensible only under one condition: the halo it generates must be one the visitor can pay off. #Applied_cultural_intelligence used to accelerate recognition of a genuinely reliable partner is legitimate. The same sequence used to disguise an unreliable one is fraud with better manners. 8.2 Tokenism and instrumental respect Respect performed for commercial advantage is a contradiction that the framework cannot fully resolve, and the paper should not pretend otherwise. Two partial resolutions are available. The first is that motive and behaviour are not the same thing, and the behaviour is genuinely respectful in its effects regardless of the motive that produced it. This is weak but not empty. The second is stronger and rests on the evidence in section 2.1: #motivational_CQ, the genuine drive to engage across difference, is the facet that most strongly predicts performance (Schlaegel, Richter and Taras, 2021). If that finding holds, an executive who is faking interest is at a real disadvantage relative to one who has it, which means the framework rewards sincerity for instrumental reasons. That is an uncomfortable defence, but it is a functional one. The practical guardrail is a simple test. Would the executive perform this act if it produced no commercial benefit? If the answer is no, the act is likely to read as instrumental, and by Proposition 4 it is likely to fail on those grounds anyway. 8.3 The host's protection A framework that only advises visitors is one-sided. Host organisations should be told what is being done to them. The countermeasure is procedural rather than psychological, because attempts to suppress bias by intention generally underperform attempts to constrain judgment by structure. Host firms can require that assessments of a counterparty's reliability be recorded on defined criteria, in writing, before and after the first meeting, and that any large positive revision be justified against evidence. They can separate the person who experiences the encounter from the person who scores the counterparty. They can insist that protocol competence be explicitly excluded from the reliability assessment, on the grounds that it carries no information about delivery. The general point is well established in the debiasing literature: structural interventions that change how a decision is made are more reliable than exhortations to think more carefully (Korteling, Paradies and Sassen-van Meer, 2023). 8.4 Distortion in the visitor's own perception Proposition 3 predicts that the primed executive will over-detect the cues they were primed on. This is not a minor caveat. An executive who has been trained to notice indirect refusal may begin to read refusal into ordinary politeness, and may conclude that a deal is dying when it is merely proceeding slowly. Two safeguards follow. The first is that priming should always be paired with base rate information: how often does this cue actually occur, and what proportion of occurrences are meaningful. The second is that interpretation should be checked against a local colleague who was not primed, precisely because they were not primed. 8.5 The stereotyping hazard Cue-based training carries an obvious risk of turning individuals into representatives of national categories. The mapping in phase 1 should therefore be local and situational rather than national, and the executive should be trained to treat a cue as a hypothesis about this person in this room, not as a fact about a nationality. The identity-based reading of how cross-cultural experience develops CQ supports this emphasis: experience builds capability when it is processed reflectively, not when it is filed as a stereotype (Pidduck, Shaffer, Zhang, Cheung and Yunlu, 2022). 9. Implications 9.1 For international executives Prepare narrowly and deeply. Choose three to five cues and one protocol, and practise both to a standard that a local observer would not question. Do not attempt breadth. Deploy once, in front of the person who decides, and do not comment on it afterwards. Treat the resulting goodwill as a loan. Spend the following weeks converting it into evidence, and volunteer the first piece of bad news yourself. Do not run the sequence if the firm cannot deliver. 9.2 For training and executive education Redesign the balance of the curriculum. If the meta-analytic evidence is right that #motivational_CQ predicts outcomes most strongly and #cognitive_CQ least strongly (Schlaegel, Richter and Taras, 2021), then a curriculum dominated by country facts is optimising the weakest lever available. Replace briefing with #deliberate_practice. Detection is a perceptual skill, and perceptual skills are built by repeated attempts with feedback, not by exposure to information. Measure detection and outcomes, not confidence. Self-report measures of CQ capture how capable participants feel, and the gap between that and how capable they are is precisely the thing training is supposed to close. 9.3 For host organisations and for firms operating in both roles Assume the sequence is being run on you, sometimes by people who have not read this paper and are doing it by instinct. Structure the assessment of counterparties so that protocol competence cannot contaminate reliability judgments. Record pre-meeting assessments and require justification for revisions. Most large firms are hosts and visitors in the same week. The most useful internal position is symmetric: train the sequence, and train the defence against it. 9.4 For theory The framework connects three literatures that have developed separately and gives each a use for the others. Attention research gains an applied setting with real stakes. #Cultural_intelligence research gains a perceptual mechanism to explain what its most predictive facets are actually doing. Social judgment research gains a case in which the halo is generated by a deliberate behavioural act rather than by an unearned physical attribute, which is a considerably more interesting object of study than a photograph. 10. Limitations and Future Research 10.1 Limitations The paper is conceptual. Nothing in it has been tested in the setting it describes. The propositions are assembled from evidence produced in other settings, and the inference that they will hold in cross-border negotiation is exactly that, an inference. The halo evidence is drawn mainly from studies of physical appearance. The claim that a behavioural act generates a halo in the same way is theoretically motivated but not directly demonstrated, and it is possible that behaviour-based halos are weaker, more fragile, or more readily discounted than appearance-based ones. Proposition 6 is the point at which the framework is most exposed. The frequency illusion is a well described phenomenon with a relatively thin experimental base compared with, for example, confirmation bias. The attentional mechanisms underlying it are well evidenced (Anderson et al., 2021; Egger and Florack, 2022), but the specific claim that trained priming reliably improves live cue detection in high-pressure business settings, rather than in laboratory tasks, is untested. The framework says little about power. A supplier in a weak bargaining position and an acquirer in a strong one are not equally able to generate or benefit from a halo, and the model as stated is silent on this. Finally, the treatment of culture in the cue mapping phase is deliberately local and situational, which is theoretically preferable but methodologically awkward, since it makes generalisation across studies difficult. 10.2 A research agenda Study 1: Detection. A randomised comparison of narrow priming, broad cultural briefing, and control, with detection of target cues in unfamiliar recorded interactions as the dependent variable, and objective coding of the recordings as the criterion. This tests Propositions 1 and 2, and, by comparing reported frequency against actual frequency, Proposition 3. Study 2: Signal properties. A vignette or video experiment manipulating visibility, difficulty, accuracy, and instrumentality of a cultural act, with host-side ratings of competence, reliability, and ethicality as outcomes. This tests Propositions 4, 5, and 6. Study 3: Warmth against competence. A direct comparison of a difficult cultural act against a difficult technical display, matched for impressiveness, with warmth and competence measured separately. This tests Proposition 8, and it is the study most likely to falsify the framework. Study 4: Reversal. A longitudinal or scenario-based design in which an initial halo is followed by disconfirming conduct, compared against disconfirming conduct with no initial halo. This tests Proposition 9, which is the proposition with the largest practical consequences. Study 5: Field outcomes. A field study within a multinational, comparing negotiation cycle time, renegotiation frequency, and dispute incidence between teams trained on the sequence and teams given conventional cultural briefing. This is the only design that tests whether any of it matters commercially. Study 6: Moderators. Replication of Study 2 across settings varying in normative tightness, relational orientation, and counterpart CQ, to test the moderators in section 3.6, including the counterintuitive prediction that the effect is weakest against the most experienced counterparts. 11. Conclusion The claim in this article is narrow and, if correct, useful. International executives who train their attention on a small number of #cultural_nuance cues will see things that untrained executives filter out. That perceptual shift is the same one that makes a newly purchased car appear on every street, and it is produced by the same attentional machinery. Acting on one such cue with an act that is visible, difficult, accurate, and evidently not a sales tactic produces a strong impression, and that impression spreads to unrelated judgments, because impression formation under thin information runs on warmth and competence and generalises freely across them. The result is that #trust is extended earlier than the evidence supports. That is an advantage, and it is also a debt. The halo is a loan against a track record the host cannot yet see, and it is repaid or it is called in. Where the visitor delivers, the sequence has simply removed friction from a relationship that deserved to work. Where the visitor cannot deliver, the sequence produces a sharper collapse than would have occurred without it. The framework is offered as a set of propositions, not as a set of findings. Its most exposed claim, that a behavioural act of cultural respect produces a halo loaded on both warmth and competence, and therefore produces more trust than a technical display of equivalent difficulty, is also its most easily tested. If that claim survives, applied #cultural_intelligence can be understood as something more precise than a set of good manners: it is the deliberate management of two ordinary #cognitive_bias mechanisms, used to let competence be recognised across a border where it would otherwise go unseen. If the claim fails, the framework should be abandoned, and the folklore with which this article opened will require a different explanation. Hashtags #AppliedCulturalIntelligence #Cultural_Intelligence #RedCarEffect #FrequencyIllusion #HaloEffect #CrossBorderTrust #GlobalNegotiation #CognitiveBias #InternationalBusiness #CQ_Framework #TrustBuilding #GlobalLeadership #BusinessProtocol #ExecutiveEducation #STULIB_Research References Anderson, B. A., Kim, H., Kim, A. J., Liao, M. R., Mrkonja, L., Clement, A., & Gregoire, L. (2021). The past, present, and future of selection history. 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Fostering assigned expatriates thriving at work through cultural intelligence and local embeddedness: The role of relational attachment. Journal of International Management, 31(2). Kordsmeyer, T. L., Freund, D., Ueshima, A., Kuroda, K., Kameda, T., & Penke, L. (2024). Halo effect of faces and bodies: Cross-cultural similarities and differences between German and Japanese observers. Personality Science, 5. https://doi.org/10.1177/27000710241257814 Korteling, J. E., Paradies, G. L., & Sassen-van Meer, J. P. (2023). Cognitive bias and how to improve sustainable decision making. Frontiers in Psychology, 14, 1129835. https://doi.org/10.3389/fpsyg.2023.1129835 Liu, X. (2025). Bridging cultures in virtual workplaces: A communication-focused review of global virtual teams. International Journal of Business Communication. https://doi.org/10.1177/23294906251327747 Livermore, D., Van Dyne, L., & Ang, S. (2022). Organizational CQ: Cultural intelligence for 21st-century organizations. 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This article examines how Major League Soccer (MLS) used the arrival of two global superstars, David Beckham in 2007 and Lionel Messi in 2023, as instruments of league strategy. Popular commentary often treats the Messi transfer as a lucky break, a moment when the greatest player in the history of the sport happened to choose an American club. This paper argues the opposite. The Messi signing was the planned end point of a sixteen year process of institutional learning that began when the MLS Board of Governors created the Designated Player Rule to accommodate Beckham. Using a qualitative comparative case study design based on document analysis, published financial reporting, peer reviewed scholarship, and process tracing, the study compares the two arrivals across five dimensions: boardroom decision making, league structure and roster rules, broadcasting and media rights, strategic marketing and brand positioning, and measurable commercial outcomes. The findings show that in 2007 the league improvised. It bent an existing rule set around one player, absorbed the shock, and then spent more than a decade converting that improvisation into permanent capability. By 2023 the league had a purpose built acquisition architecture: a flexible roster system, a single global streaming partner, a mid season tournament designed for cross border audiences, privately financed stadiums, and a deal structure that gave the player a share of the value he created. The paper concludes that #superstar_acquisition in MLS evolved from an emergency marketing tactic into a repeatable strategic capability, and that the true legacy of the Messi era will be judged by what the league does with the structural reforms it approved in 2025 and 2026, not by the player himself. Keywords: Major League Soccer, Designated Player Rule, superstar economics, sport governance, media rights, single entity structure, strategic marketing, sport management history 1. Introduction On 13 July 2007, David Beckham was presented to a crowd at the Home Depot Center in Carson, California, wearing the white shirt of the Los Angeles Galaxy. Sixteen years and two days later, on 15 July 2023, Lionel Messi signed for Inter Miami CF, a club owned in part by David Beckham himself. The symmetry is almost too neat, and it has encouraged a great deal of loose writing about fate, destiny, and the circle closing. This article resists that reading. The central claim here is straightforward. The arrival of Messi in MLS was not a #serendipitous_moment. It was the calculated output of a league that had spent sixteen years building the legal, commercial, and #media_rights infrastructure required to absorb a player of that magnitude. In 2007, MLS had one superstar and no system. In 2023, MLS had a system and went out to find the superstar who would test it at full stretch. Understanding the difference matters for #sports_management scholarship for three reasons. First, MLS is an unusual organisational form. It operates as a #single_entity, meaning the league itself, rather than the individual clubs, holds player contracts and centrally controls a large share of commercial rights. Investor operators run the clubs but they are shareholders in one company. This structure was designed in the 1990s to prevent the salary escalation and franchise collapse that destroyed the old North American Soccer League. It also means that any change to how the league acquires elite talent requires a collective decision by the #board_of_governors. A star signing in MLS is therefore never simply a club decision. It is a constitutional event. Second, the two arrivals bracket a period of extraordinary change in how sport is distributed and consumed. Beckham arrived in a world of cable television, regional sports networks, and rights fees so small that MLS was effectively paying broadcasters for airtime. Messi arrived into a ten year global #streaming agreement with a technology company, a deal that removed the geographic fragmentation of rights entirely. The comparison therefore offers a natural experiment in how #broadcasting_rights shape, and are shaped by, talent strategy. Third, the two cases allow a test of a common assumption in the literature on the #superstar_effect. Economic models predict that a small number of exceptional performers capture disproportionate rewards because audiences prefer the very best and technology allows one performance to be consumed by many people at low marginal cost. What those models say less about is the organisational precondition. A superstar can only generate returns if the league that hosts him has the capacity to capture, distribute, and reinvest the value created. This is the question at the centre of this paper. 1.1 Research questions The study addresses four questions. What decision processes inside the MLS boardroom produced the Designated Player Rule in 2006 and 2007, and how did those processes differ from the deliberations that preceded the Messi signing in 2023? How did MLS league structure, particularly #roster_rules and #salary_cap mechanisms, change between the two arrivals, and to what extent were those changes causally linked to the lessons of the Beckham period? How did the transformation of the league's #media_rights strategy, culminating in the 2022 agreement with Apple, alter the strategic value of a superstar signing? What does the comparison reveal about the transition from #improvised_marketing to a repeatable strategic capability in an emerging professional league? 1.2 Contribution and structure The paper contributes an integrated, historically grounded account that connects four literatures normally kept apart: superstar economics, league governance, sport media economics, and brand strategy. It also offers a corrective to journalistic framing that credits individual charisma for outcomes that were, in fact, produced by rule design. The article proceeds as follows. Section 2 reviews the relevant literature. Section 3 sets out the theoretical framework. Section 4 explains the method. Sections 5, 6, and 7 present the three empirical phases: the Beckham arrival, the intervening period of institutional learning, and the Messi arrival. Section 8 offers a structured comparison. Section 9 discusses implications, including the 2027 calendar reform. Section 10 acknowledges limitations, and Section 11 concludes. 2. Literature Review 2.1 The economics of the superstar The theoretical starting point remains Rosen's account of superstar markets, in which small differences in talent produce very large differences in reward because consumers are unwilling to substitute many mediocre performances for one excellent performance, and because technology lets a single performance reach a mass audience (Rosen, 1981). Applied to sport, this predicts that the presence of an elite athlete should raise demand not only for his own team's matches but for matches he plays away from home, a phenomenon usually called the #superstar_externality. Empirical work in North American sport has generally supported the existence of such externalities while showing that they are smaller and more conditional than popular accounts suggest. Watanabe, Imbrogno, and Mills (2024) studied Shohei Ohtani in Major League Baseball and found a substantial away attendance effect, particularly in the period when audiences were returning after the pandemic. Their key insight is in the title: superstars really are scarce. The effect is not a property of famous players in general. It is a property of a very small number of genuinely unique performers. This scarcity finding is important for the MLS case, because it explains why the league's attempt to generalise from Beckham to a broader class of "designated players" produced disappointing results. Rewilak (2023), using a difference in differences design on the 2007 season, found that the apparent attendance gains from the first cohort of designated players largely disappeared once appropriate controls were applied, and that the aggregate compensation paid to those players could not plausibly be recovered from incremental ticket revenue alone. Earlier work by Lawson, Sheehan, and Stephenson (2008) had found a positive but modest ticket sales effect for Beckham specifically. Warren and Ross (2011), in the paper that gave the policy debate its name, argued that the Designated Player mechanism worked for Beckham and worked poorly for almost everyone else. The literature therefore contains a puzzle. If the #Designated_Player_Rule was a weak instrument for driving attendance, why did MLS keep it, extend it, and build on it for sixteen years? This paper argues the answer is that attendance was never the main mechanism of value capture. The rule's real function was to make the league legible and attractive to international audiences, sponsors, expansion investors, and eventually media buyers. The measurable payoff was in #franchise_valuation and rights fees, not in turnstile counts. Recent evidence on Messi supports this reading while also demonstrating a demand shock of a different order. Gong and Watanabe (2025) examined secondary market ticket prices and found that Messi's arrival raised prices for Inter Miami home matches by somewhere between roughly eleven and twelve times, and for away matches by between four and five times, relative to the pre arrival baseline. They also found a spillover effect on matches not involving Inter Miami, though this varied by club and was in some cases negative. The distributional pattern matters. A superstar who lifts one club's revenues while leaving others flat creates internal political pressure in a #single_entity league where revenues are pooled. 2.2 League structure, governance, and competitive balance MLS was built deliberately against the memory of the North American Soccer League, which expanded quickly, paid enormous wages to ageing European stars, and collapsed in 1984. The single entity model was intended to hold wages down, distribute talent evenly, and protect weaker markets. It also served a legal purpose, since a single company cannot easily be accused of conspiring with itself to restrain trade in the labour market, an argument that has been contested but never fully defeated in United States courts. The tension between #competitive_balance and star power is therefore structural in MLS, not incidental. Every exception to the salary budget, from the first Designated Player slot to #Targeted_Allocation_Money and the #U22_Initiative, represents a negotiated retreat from the founding logic. Scholarship on league governance suggests that such retreats tend to be path dependent: once a league creates a mechanism for exceeding a cap, the mechanism tends to widen rather than close, because the clubs that benefit most acquire an interest in defending it. Chadwick (2022) situates such decisions within a broader shift away from a purely utilitarian, closed market model of sport management towards what he describes as a geopolitical economy of sport, in which leagues, clubs, and states use sporting assets to pursue visibility, soft power, and market access. MLS is not a state actor, but its behaviour after 2015 fits the pattern. The league increasingly treated itself as a competitor in a global market for attention rather than as a domestic property competing only with American football, basketball, and baseball. 2.3 Media rights and the arrival of technology platforms The third literature concerns the migration of sport from broadcast to #streaming. Fakataulavelua, Lang, and Moulard (2023) mapped the entry of large technology firms into football, distinguishing between companies that buy rights aggressively, companies that experiment, and companies that support the industry through infrastructure and services. Their framework helps explain why the eventual MLS partner was Apple rather than a traditional network. A conventional broadcaster values live sport as a driver of advertising inventory within a national market. A technology platform values it as a driver of subscription, device engagement, and global reach. This difference reshapes what a superstar is worth. To a national broadcaster, Messi is worth whatever additional advertising revenue his matches attract in the United States. To a global streaming partner, he is worth every subscriber he attracts anywhere on earth. The 2022 agreement between MLS and Apple, reported at roughly two and a half billion United States dollars over ten years with a guaranteed annual minimum, was the first time an American league sold worldwide rights to a single buyer without regional carve outs. It is difficult to overstate how much this changed the arithmetic of a star signing. 2.4 The gap this paper addresses The existing literature treats these three domains separately. Economists measure demand effects. Governance scholars analyse structure. Media scholars analyse rights. What is missing is an account of how a single league sequenced changes across all three domains over almost two decades in pursuit of one goal, and how a signing that looked spontaneous was in fact the product of that sequencing. That is the gap addressed here. 3. Theoretical Framework Three concepts organise the analysis. 3.1 Path dependence #Path_dependence describes situations where an early choice constrains and channels later choices, so that the sequence of events matters as much as the merits of any single decision. The Designated Player Rule is the classic instance. Once MLS demonstrated that it would rewrite its rulebook to accommodate one exceptional player, it could not credibly refuse to do so again. The rule created an expectation, a precedent, and a constituency. Every subsequent roster reform can be read as an attempt to manage the consequences of that first exception rather than to reverse it. 3.2 Dynamic capabilities The #dynamic_capabilities perspective asks how organisations sense opportunities, seize them, and reconfigure their assets to exploit them. Applied here, the framework distinguishes sharply between the two arrivals. In 2007 MLS sensed an opportunity and seized it, but it had almost no capacity to reconfigure. The Galaxy signed Beckham with a squad, a stadium, a marketing department, and a television contract that were all designed for a much smaller league. The organisation could not absorb what it had caught. By 2023 the league possessed all three capabilities in a matured form. It had a scouting and commercial apparatus that had been tracking Messi's availability for years. It had a roster mechanism that could accommodate a contract of that size. It had a media partner with a direct interest in helping to finance the deal. And it had a mid season tournament, the #Leagues_Cup, which happened to begin immediately after the transfer window in which Messi arrived. Whether that timing was designed or fortunate, the league was in a position to exploit it. 3.3 Institutional legitimacy Emerging leagues face a #legitimacy problem before they face a revenue problem. Sponsors, broadcasters, investors, and elite players will not commit until they believe the property is credible. Both signings were, at their core, legitimacy transactions. Beckham was purchased to prove that MLS existed. Messi was purchased to prove that MLS mattered. The difference between those two propositions is the subject of this paper. 4. Methodology 4.1 Design The study uses a qualitative, theory guided comparative case study with two focal cases (Beckham 2007, Messi 2023) separated by an intervening period treated as a transformation phase (2008 to 2022). The comparative case method is appropriate because the unit of analysis, a league wide strategic decision, is rare, historically situated, and not amenable to experimental manipulation. 4.2 Data sources Four categories of evidence were used. Peer reviewed scholarship on superstar demand effects, roster rule design, and sport media economics. Long form journalistic accounts with documented access to league and club decision makers, principally the two book length treatments of the respective arrivals: Wahl's contemporaneous account of the Beckham period and Tenorio's account of the Messi period, which draws on interviews inside Inter Miami and the league office. Publicly reported financial and structural information: rights fee values, expansion fees, contract terms, salary budget figures, and Board of Governors decisions. Performance and demand data reported in the academic literature, including attendance, secondary market pricing, and valuation estimates. 4.3 Analytical procedure The analysis follows a #process_tracing logic. For each of the five comparative dimensions, evidence was assembled chronologically and examined for causal links between an observed problem in the Beckham period and a subsequent structural reform. A reform was coded as strategically responsive when three conditions held: a documented failure or constraint in the earlier period, a subsequent rule or contract change addressing that constraint, and observable use of the changed rule during the Messi transaction. 4.4 Limitations of the method MLS boardroom deliberations are not public. Claims about internal debate therefore depend on the accounts of journalists with access, and those accounts cannot be independently verified. Where such claims are used they are flagged as reported rather than established. Financial figures for player compensation in MLS are frequently reported in ranges and include commercial components that are not disclosed. All monetary figures in this paper should be read as reported estimates. 5. Phase One: The Beckham Arrival, 2006 to 2012 5.1 The state of the league in 2006 To understand the boldness of the Beckham decision it is necessary to recall how small MLS was. The league had begun play in 1996 with ten clubs, had contracted to ten after folding two Florida franchises in 2001, and had spent its first decade losing money. Most clubs played in oversized American football stadiums. The salary budget for an entire roster was measured in low single digit millions of United States dollars. National television exposure was minimal, and in some years the league effectively purchased its own airtime rather than being paid for it. The one genuine asset the league had built was Soccer United Marketing, created in 2002. #Soccer_United_Marketing held commercial rights not only to MLS but to the Mexican national team's matches in the United States and to other soccer properties. It was, in effect, a hedge. If the league could not yet sell itself, it could sell soccer. 5.2 The boardroom problem The Beckham negotiation created a governance crisis in miniature. Under the existing rules, no club could pay a player more than a small fraction of the team budget. Beckham's representatives were asking for a package that exceeded the entire payroll of most clubs. The league had three options: refuse, break its own rules informally, or change the rules. It changed the rules. In November 2006 the Board of Governors approved a mechanism allowing each club to sign one player whose salary would count against the team budget only up to a capped charge, with the remainder paid by the club's investor operator. The rule was formally the Designated Player Rule and was immediately nicknamed the #Beckham_Rule. The reported internal debate is instructive. Owners in smaller markets were being asked to approve a rule whose primary beneficiary would be a large market club, and which would raise wage expectations across the league. The counterargument, which prevailed, was that a rising tide argument applied: any club could use the mechanism, and the league as a whole would gain visibility. This is the first appearance of a tension that recurs across the entire period, between #collective_restraint and individual ambition. 5.3 The commercial architecture of the deal Beckham's guaranteed salary with the Galaxy was reported at around six and a half million United States dollars a year on a five year contract. The much publicised figure of two hundred and fifty million United States dollars referred to a projected total package including endorsements, image rights, and a share of commercial revenues, most of which was contingent and much of which was never realised in the amounts forecast. Two elements of the contract mattered far more than the headline number. The first was a share of league and club commercial upside, which aligned Beckham's interests with the growth of the property rather than merely with his own performance. This was novel in North American sport, where players are conventionally paid a fixed wage and take no equity in the enterprise. The second, and by far the more consequential, was an option permitting Beckham to purchase an MLS expansion franchise at a fixed and heavily discounted fee, reported at twenty five million United States dollars. At the time this was treated as a curiosity. It would prove to be the single most important clause in the history of the league. 5.4 What went right Judged against the goal of #visibility, the Beckham signing succeeded immediately. Media coverage of MLS increased by an order of magnitude. Away matches sold out. Jersey sales rose sharply. International broadcasters who had never previously carried MLS content took the games. The league acquired, for the first time, a reason for a casual global audience to look at it. The signing also changed investor perception. Expansion fees, which had been effectively nominal in the league's early years, began a long climb. Seattle Sounders FC entered in 2009 and demonstrated that a well run club in an engaged market could draw crowds comparable to a mid tier European club. The #soccer_specific_stadium movement accelerated, giving clubs control of their own match day revenue for the first time. 5.5 What went wrong The failures were equally clear and, for the argument of this paper, more important. The sporting integration was poor. The Galaxy squad around Beckham was weak, the team missed the playoffs in his first two seasons, and his loan spells to AC Milan in 2009 and 2010 exposed the league to the accusation that it was a retirement destination which its own marquee player did not take seriously. Wahl's contemporaneous account documents a dressing room in which the commercial machinery around the player and the sporting operation of the club were pulling in opposite directions. The league had no #media_rights vehicle capable of monetising the attention. Whatever global interest Beckham generated flowed into third party broadcasters at rates negotiated before he arrived. MLS captured the publicity and very little of the revenue. The rule did not generalise. Once one Designated Player slot existed, clubs used it, but they used it mostly on players who were neither globally famous nor sportingly transformative. The empirical literature, as noted, finds that the attendance benefit of the designated player cohort as a whole was small and possibly negligible once controls are applied (Rewilak, 2023; Warren and Ross, 2011). MLS had built a mechanism for buying stars without building a mechanism for identifying which stars were worth buying. Finally, the league had no answer to the question of what happened next. Beckham left the Galaxy after the 2012 season, having won two MLS Cups. Attendance and interest did not collapse, but neither did they continue to compound. The league had received a shock, not a trajectory. 5.6 Interim assessment The Beckham period should therefore be understood as a successful #proof_of_concept attached to a failed system of value capture. MLS proved that a global star would come, that American audiences would respond, and that the world would pay attention. It could not yet convert any of that into durable revenue. Everything that follows is an attempt to solve that problem. 6. Phase Two: The Long Construction, 2013 to 2022 This is the section most often skipped in popular accounts, and it is where the actual strategy was built. 6.1 Rebuilding the roster mechanism Between 2010 and 2021 MLS progressively dismantled the rigidity that had made the Beckham exception necessary in the first place. The Designated Player allowance was expanded from one slot to two in 2010 and to three by 2012, with a reduced budget charge for younger designated players intended to encourage clubs to buy players with resale value rather than declining veterans. #General_Allocation_Money, a pool of discretionary funds clubs could use to buy down salary budget charges, was formalised and expanded. #Targeted_Allocation_Money was introduced in 2015 specifically to allow clubs to sign or retain high quality players in the tier immediately below Designated Player level. This addressed a defect the Beckham era had exposed: a squad with one enormous salary and twenty minimum salaries is not a competitive football team. The #U22_Initiative, introduced for the 2021 season, allowed clubs to sign young players at reduced budget charges, explicitly reorienting the league towards development and resale. Read as a sequence, these reforms describe an organisation learning that a star is only an asset if the surrounding squad can support him and if the club can generate transfer value independently. The rules were being rewritten so that the next superstar would arrive into a functioning football operation rather than a marketing campaign with a football team attached. The reforms were contested. Reporting from the period indicates persistent boardroom disagreement between clubs that wished to spend aggressively and clubs that feared cost escalation, and between those who saw #roster_rules as a competitive balance instrument and those who saw them as an obstacle to global relevance. The #board_of_governors resolved these disputes incrementally, by adding new mechanisms rather than abolishing old ones, which produced the famously complex rulebook the league still operates. 6.2 Expansion, stadiums, and the capital base Between 2015 and 2025 MLS expanded from twenty to thirty clubs. Expansion fees rose from tens of millions to a reported five hundred million United States dollars for San Diego FC, which began play in 2025. Each new club brought capital into the system, and most brought a privately financed soccer specific stadium. This matters for the argument because #expansion_fees were, in effect, the financing mechanism for the league's long term strategy. A league that loses money on operations but sells new shares at rising prices can fund a great deal of patient investment. The rising fees were themselves partly a function of the visibility Beckham had generated and of the growing conviction among investors that soccer in North America was a structurally undervalued asset ahead of the 2026 World Cup. 6.3 The Beckham option is exercised In 2014, Beckham announced his intention to exercise the expansion option written into his 2007 contract. After a protracted struggle over stadium sites in Miami, the franchise was formally awarded in 2018 and Inter Miami CF began play in 2020, with Beckham as co owner alongside Jorge Mas and Jose Mas. The strategic significance is difficult to overstate. The rule change made for one player in 2006 had, by 2020, produced a club whose ownership group combined the most globally recognised figure in the history of American soccer with a Miami based construction and infrastructure family capable of financing a privately built stadium. #Inter_Miami was, from birth, the vehicle best positioned in the league to execute an acquisition that no other club could contemplate. Path dependence is rarely so legible. The Designated Player Rule created Beckham the player, Beckham the player created Beckham the owner, and Beckham the owner created the only club in MLS with both the relationships and the ambition to sign Lionel Messi. 6.4 The media rights transformation The final and most decisive piece was the sale of media rights. Under the 2014 to 2022 arrangements, MLS content was split among ESPN, Fox, and Univision in the United States, with separate deals in Canada and elsewhere. Aggregate national rights income was reported at around ninety million United States dollars per year across all partners, a figure that placed MLS far below the other North American leagues and below several European leagues. Crucially, rights were fragmented by territory, which meant that any global interest generated by a star player leaked away into markets where MLS held nothing. In June 2022 MLS announced a ten year agreement with Apple, reported at a minimum of two and a half billion United States dollars in total, under which Apple would carry every MLS match worldwide through a dedicated product, #MLS_Season_Pass, beginning with the 2023 season. There were no regional blackouts and no territorial carve outs. For the first time in the history of North American professional sport, a league had sold its entire global inventory to one buyer. Three features of this deal are essential to the argument. First, it eliminated leakage. Any incremental global audience generated by a signing would now flow directly to the league's own partner and, through the revenue sharing terms, back to the league. Second, it changed the identity of the buyer. Apple was not purchasing advertising inventory. It was purchasing subscriber acquisition and engagement. This made Apple a natural co investor in any asset capable of driving subscriptions, which is precisely what a global superstar is. Third, it created a structural incentive for the league to find that superstar quickly. A guaranteed minimum payment protects the seller, but the upside terms of the deal, which reportedly allowed MLS to share in revenue above a subscription threshold, only pay out if the product attracts an audience. Having signed a global rights deal, MLS now needed a global reason for people to subscribe. The deal was announced in June 2022. Messi's contract with Paris Saint Germain was due to expire in June 2023. 6.5 Leagues Cup The final structural piece was competitive. In 2023 MLS and Liga MX expanded the #Leagues_Cup into a full scale tournament involving every club in both leagues, played in a dedicated mid season window with the domestic league paused. Qualification for the CONCACAF Champions Cup was attached to it, giving it sporting weight. The tournament served several strategic purposes at once. It monetised the Mexican American audience, historically the largest soccer audience in the United States and one that MLS had struggled to convert. It created a compressed, high attention event with knockout stakes. And it began in late July 2023, which is to say within days of Messi's debut. 7. Phase Three: The Messi Arrival, 2023 to 2026 7.1 The negotiation Messi's departure from Paris Saint Germain was confirmed in the spring of 2023. The competing offers were, on the face of it, incomparable. A Saudi Arabian club was reported to have offered a sum vastly larger than anything MLS could match. A return to FC Barcelona was widely discussed and, for reasons connected to that club's financial position, never became a firm proposal. On 7 June 2023 Messi announced his decision to join Inter Miami. He signed on 15 July and was presented the following day. 7.2 The architecture of the deal The Messi contract is the single clearest piece of evidence for the thesis of this paper, because it could not have been constructed in 2007. It required every structural element the league had built in the intervening period. The reported components were as follows. A base contract, reported at around one hundred and fifty million United States dollars over an initial two and a half year term, financed through the Designated Player mechanism and through the personal resources of the Inter Miami ownership group. A share of #MLS_Season_Pass subscription revenue attributable to new subscribers, agreed with Apple. This is the decisive innovation. It converted the league's media partner into a co financier of the signing. Apple was not simply broadcasting Messi. Apple was paying for him, because Apple was the party that would capture the largest share of the global audience he brought. A share of commercial revenue from Adidas, which sponsors both Messi and the league, structured on similar logic. An option to acquire an equity stake in Inter Miami at the conclusion of his playing career, reportedly discussed as part of the package. This directly echoes the Beckham expansion option of 2007 and shows the league consciously reusing a mechanism it had already tested. Compare this to 2007. Beckham was paid by a club, with a commercial upside that the league lacked the infrastructure to deliver. Messi was paid by a club, a technology company, and an apparel manufacturer, each of which had a direct and quantifiable interest in his global reach. This is not the same kind of transaction. It is a #syndicated_investment in an asset, structured so that every party that captures value also contributes capital. 7.3 The boardroom in 2023 Reported accounts of the league's internal deliberations describe a very different atmosphere from 2006. The question in 2006 had been whether to permit the signing at all. The question in 2023 was how to distribute the benefits. The tension was predictable. Inter Miami would capture a disproportionate share of the direct gains: ticket revenue, sponsorship, merchandising, and franchise value. The rest of the league would receive the indirect benefits: away match sell outs, subscription growth, and a rising tide of league wide valuation. Given that the league is a single entity in which owners are shareholders in a common enterprise, this asymmetry was manageable, but it was not frictionless. The academic evidence suggests the owners were right to worry. Gong and Watanabe (2025) found that while Inter Miami's own ticket prices rose by an extraordinary margin and away prices rose substantially, the spillover to matches not involving Inter Miami was inconsistent and in some markets negative. A #superstar_externality is not evenly distributed. Clubs that hosted Messi benefited enormously. Clubs that did not, in a given season, may have benefited very little. Reported accounts also indicate a second and more consequential debate, one that continued well beyond the signing itself: whether the league should use the Messi window to loosen its spending rules permanently, in effect abandoning the last of the founding restraint in order to convert temporary attention into permanent quality. This debate has not been settled, and it is the subject of Section 9. 7.4 Outcomes The commercial results were immediate and, by any prior standard of MLS, extraordinary. On demand, the secondary market evidence is the most rigorous available. Inter Miami home match resale prices rose by a factor of roughly eleven to twelve, and away match prices by a factor of four to five, relative to the pre announcement baseline (Gong and Watanabe, 2025). On merchandise, the Inter Miami shirt bearing Messi's name became the league's leading seller and, by widely reported industry accounts, one of the best selling football shirts in the world. On #franchise_valuation, Inter Miami's estimated value passed one billion United States dollars, reported at approximately 1.19 billion in early 2025, placing an expansion club founded in 2018 among the most valuable properties in the league. On sporting outcomes, the club won the 2023 Leagues Cup, the 2024 Supporters' Shield with a league record points total, and the 2025 MLS Cup, defeating Vancouver Whitecaps FC 3 to 1 in the final on 6 December 2025. Messi was named the league's most valuable player in 2024 and won the Golden Boot in 2025 with twenty nine goals in twenty eight appearances. In October 2025 he signed an extension through the 2028 season, timed to coincide with the opening of #Miami_Freedom_Park, the club's privately financed stadium, in 2026. On media, the picture is more complicated, and this is where the strategy encountered its first serious limit. 7.5 The paywall problem The Apple agreement solved the leakage problem by consolidating global rights. It created a new problem by placing almost all MLS content behind a subscription wall. For a league whose core strategic need was to convert casual attention into habit, this was a significant constraint. A viewer who was curious about Messi had to make a purchase decision before watching a single minute. Industry reporting through 2023, 2024, and 2025 consistently indicated that #MLS_Season_Pass subscriber growth did not meet the ambitious expectations set at the launch of the deal, despite the presence of the most famous athlete in the world. The league and Apple responded in stages. Selected marquee matches and the playoffs were made available to the broader Apple TV subscriber base rather than only to Season Pass purchasers, and league executives reported meaningful increases in viewership when the barrier was removed. In November 2025 the two parties announced the most significant reversal to date: from the 2026 season, MLS Season Pass would cease to exist as a separate product, and all MLS matches would be included within the standard Apple TV subscription, with the financial terms of the underlying agreement restructured accordingly. This is a striking admission. The league had spent sixteen years building an apparatus to capture the value of a global superstar, secured the superstar, and then discovered that its distribution architecture was suppressing the very reach the signing was meant to generate. The #paywall was not a minor operational detail. It was, in the judgement of the parties themselves, an error significant enough to require rebuilding the commercial terms of a ten year agreement three seasons into its life. 8. Comparative Analysis The following structured comparison draws the two cases together across the five dimensions identified in Section 1. 8.1 Boardroom decision making 2007. Reactive. The Board of Governors was presented with an opportunity it had not planned for and responded by creating a permanent rule to accommodate a single transaction. The decision was contested, the primary objection being that the rule advantaged large market clubs and threatened cost discipline. The rule passed because the perceived benefit to league visibility outweighed the perceived risk. 2023. Anticipatory. The mechanisms required to sign Messi already existed. The Designated Player Rule, allocation money, and the freedom of investor operators to fund contracts privately had all been in place for a decade or more. The boardroom debate concerned distribution of benefit and, subsequently, whether to use the moment to reform spending rules permanently. No new rule was required to permit the signing. The shift is from #rule_creation to #rule_deployment. That is the definition of an institutionalised capability. 8.2 League structure 2007. A rigid salary budget with a single narrow exception, no mechanism for building a supporting squad, no meaningful development or resale system. 2023. A layered system of Designated Player slots, General Allocation Money, Targeted Allocation Money, and the U22 Initiative, permitting a club to place a superstar alongside a competitive supporting cast and a pipeline of resaleable young players. Inter Miami used the full range, pairing Messi with Sergio Busquets, Jordi Alba, Luis Suarez, and later Rodrigo De Paul. The strategic lesson learned between the two periods is that a superstar is a #multiplier, not a substitute. He multiplies the value of a good team and does relatively little for a poor one. The 2007 Galaxy proved the negative case. The 2024 and 2025 Inter Miami squads proved the positive one. 8.3 Broadcasting and media rights 2007. Fragmented, territorially bounded, low value, and negotiated before the signing. The league had no ability to capture the global attention Beckham generated. 2023. Consolidated, global, exclusive, and negotiated in anticipation of exactly such a signing. The media partner became a co financier of the player. Value that had leaked away in 2007 was captured in 2023. 2026. Restructured, with the paywall removed, in acknowledgement that capture without reach is self defeating. This dimension shows the clearest evidence of strategic learning, and also the clearest evidence that the learning was incomplete. 8.4 Strategic marketing and brand positioning 2007. The message was: soccer has arrived in America. The target audience was domestic and casual. Beckham was positioned as a crossover celebrity, and the marketing leaned heavily on his fame outside the sport. 2023. The message was: the best player in the world plays here. The target audience was global and, domestically, was aimed squarely at the Hispanic and diaspora communities that MLS had historically underserved. Messi was positioned not as a celebrity but as the definitive sporting authority in the game, a claim MLS had never previously been able to make about anything. The difference in #brand_positioning is fundamental. Beckham legitimised MLS as entertainment. Messi legitimised it as football. The Leagues Cup, the Miami location, the pink shirt, and the Spanish language commercial strategy were all constructed around the second proposition. 8.5 Commercial outcomes 2007. Sharp, temporary rises in attendance and coverage. Modest measurable revenue gains. Substantial long term effect on expansion fees and investor confidence. Weak evidence of a sustained attendance effect for the designated player class as a whole (Rewilak, 2023). 2023. Extreme and measurable demand shock at Inter Miami, with substantial away spillover and inconsistent league wide spillover (Gong and Watanabe, 2025). Franchise valuation more than doubled. Global merchandise leadership. Underwhelming subscription performance relative to expectations, subsequently addressed by restructuring the distribution model. 8.6 Summary of the comparison Dimension Beckham, 2007 Messi, 2023 Trigger for rule change Signing forced the rule Rule enabled the signing Financing Club and personal endorsements Club, media partner, and apparel partner Rights structure Fragmented, territorial Consolidated, global Squad context Weak supporting cast Deliberately assembled elite core Player equity Expansion option, exercised in 2018 Reported equity option in the club Primary objective Existence and visibility Relevance and global subscription Principal weakness No value capture mechanism Value captured but reach restricted 9. Discussion 9.1 The thesis restated The evidence supports the central claim. The Messi signing was not a fortunate accident. It was made possible by a chain of decisions each of which is traceable to the constraints exposed in 2007. The Designated Player Rule made a contract of that size legally possible. The expansion option in Beckham's contract created the club that signed him. Targeted Allocation Money and the U22 Initiative created the squad that made him effective. The Apple agreement created the buyer that helped pay for him and captured the audience he attracted. The Leagues Cup created the stage on which he debuted. Rising expansion fees created the capital that financed the wait. Remove any one of those links and the transaction becomes difficult. Remove two and it becomes impossible. This is what is meant by describing the signing as the #calculated_apex of a strategic evolution rather than a serendipitous cultural moment. 9.2 The limits of the superstar strategy It would be a mistake to read this as an unqualified success story, and the evidence does not permit it. The demand effects, though enormous at Inter Miami, were uneven across the league (Gong and Watanabe, 2025). The subscription business underperformed to the point that the distribution model had to be rebuilt. The academic literature on the broader designated player cohort continues to find weak aggregate effects (Rewilak, 2023), which suggests that MLS has learned how to sign one transcendent player without learning how to sign fifty very good ones. There is also a demographic problem. Messi turned thirty eight in 2025. His extension runs through 2028. The strategy has a defined and rapidly approaching expiry date, and the league has no obvious successor asset. This is the sharpest difference from 2007. Beckham arrived at thirty two with a decade of relevance ahead of him and, as it turned out, an option that would keep him inside the league permanently. Messi's post playing role remains undefined. 9.3 The reforms of 2025 and 2026 as the real legacy The most consequential development of the Messi era may have nothing directly to do with Messi. On 13 November 2025, the MLS Board of Governors voted to abandon the spring to autumn calendar that the league had used since 1996 and to adopt a summer to spring calendar aligned with the major European leagues, effective from the 2027 to 2028 season. A shortened transition season of fourteen matches will be played from February to May 2027. The league will observe a mid winter break, and the regular season will conclude in April with the playoffs in May. The stated rationale, articulated by the commissioner and by club executives, was competitive and commercial rather than sentimental. Under the old calendar the primary international transfer window opened in the middle of the MLS season, which meant MLS clubs negotiated from a position of structural weakness in both directions. International windows interrupted the season. And the playoffs competed for attention with American football at the worst possible time of year. This is a far more radical act than signing any individual player. It reverses a founding assumption of the league. It required rewriting player contracts, stadium agreements, sponsorship deals, and the media agreement itself. It was approved, on the reporting available, because the boardroom had been persuaded that MLS must compete in the global market for players rather than in the domestic market for attention. That persuasion is a direct product of what the league learned during the Messi period, which demonstrated both the size of the global audience available and the structural obstacles preventing MLS from reaching it. The parallel restructuring of the Apple agreement and the abolition of the Season Pass paywall belong to the same logic. So does the continuing and unresolved boardroom argument about #spending_rules, which reporting suggests is proving a harder sell than the calendar change. It is one thing to move the season. It is another to abandon the cost discipline on which thirty owners built their equity. 9.4 Theoretical implications Three implications follow for the sport management literature. First, the superstar effect literature would benefit from a stronger treatment of #absorptive_capacity. The MLS case shows that the same class of asset, a globally transcendent player, produced radically different returns in 2007 and 2023 not because the players differed in quality but because the host organisation differed in its capacity to capture value. Demand side models that treat the league as a passive recipient of a demand shock will systematically misestimate the effect. Second, the case is a strong illustration of path dependence in league governance. The 2006 rule change was made under pressure, was contested, and was justified as a narrow exception. It became the organising principle of the league's strategy for the following two decades. Third, the case supports the argument that the boundary between a sports league and a media platform is dissolving. The Messi contract, in which the streaming partner pays part of the player's wages in exchange for the subscribers he brings, is not a broadcasting arrangement. It is a joint venture in content. Sport management scholarship has not yet fully absorbed what this means for how leagues should be modelled. 9.5 Practical implications for emerging leagues For managers of emerging leagues elsewhere, the sequence matters more than the signing. Build the #value_capture architecture first. A star acquired before the rights structure exists will generate attention that flows to somebody else. Build the supporting squad mechanism. A star in a weak team is a marketing campaign, not a sporting product, and audiences distinguish between the two faster than executives expect. Do not confuse capture with reach. The MLS experience with the paywall is the clearest available demonstration that a perfectly designed value capture system can fail if it prevents people from watching. Plan the succession. A strategy with an expiry date is not a strategy. It is a window. 10. Limitations This study relies on public and journalistic sources for internal decision processes that are not directly observable. Boardroom accounts, however well sourced, are reconstructions. Financial figures for player compensation in MLS are reported rather than disclosed, and frequently blend guaranteed salary, contingent commercial income, and third party payments in ways that resist precise decomposition. The Messi period is ongoing. His contract runs to 2028, the calendar reform takes effect in 2027, and the restructured media agreement began in 2026. Any assessment of outcomes is therefore provisional, and the most important tests of the strategy, particularly what happens to demand after Messi retires, lie in the future. Finally, the study is a comparison of two cases. It establishes a plausible causal chain through process tracing but cannot rule out alternative explanations, most obviously the general growth of soccer interest in the United States over the same period, driven by demographic change, the success of the men's and women's national teams, and the widespread consumption of European football by American audiences. 11. Conclusion Between 2007 and 2023, Major League Soccer transformed the acquisition of a global superstar from an act of desperation into an act of design. In 2007 the league had a rule it invented overnight, a media contract that gave away the value it was about to create, a squad that could not support the player it had bought, and no plan for what to do when he left. It nonetheless proved something essential: that the world would look. In 2023 the league had a mature roster architecture, a global media partner with a financial stake in the outcome, a club built by its own previous superstar, a mid season tournament aimed at the audience it most needed to reach, and a contract structure in which every party that captured value also paid for it. It nonetheless discovered something uncomfortable: that it had built a wall between the player and the audience he was signed to attract. The lesson of the comparison is not that MLS got lucky twice. It is that the league spent sixteen years converting a #lucky_break into a #capability, and that the capability, not the player, is the asset. The Designated Player Rule was the seed. The Apple agreement, the Leagues Cup, the allocation money system, Inter Miami itself, and finally the calendar realignment of 2027 are the tree. Messi will retire. The rulebook will not. When historians of #sport_management assess this period, the correct object of study will not be the player who arrived in Miami in the summer of 2023. It will be the sixteen years of #institutional_learning that made his arrival possible, and the far more difficult reforms that his presence finally gave the boardroom the confidence to approve. Hashtags #MLS_strategy #Beckham_Rule #Designated_Player_Rule #Lionel_Messi #David_Beckham #Inter_Miami #sport_management #sports_business #media_rights #streaming_economics #superstar_economics #league_governance #single_entity_league #soccer_in_America #strategic_marketing References Chadwick, S. (2022). From utilitarianism and neoclassical sport management to a new geopolitical economy of sport. European Sport Management Quarterly, 22(5), 685 to 704. https://doi.org/10.1080/16184742.2022.2032251 Bradbury, J. C., Coates, D., & Humphreys, B. R. (2023). The impact of professional sports franchises and venues on local economies: A comprehensive survey. Journal of Economic Surveys, 37(4), 1389 to 1431. https://doi.org/10.1111/joes.12533 Fakataulavelua, A., Lang, M., & Moulard, J. (2023). Streaming the beautiful game: Exploring big tech's growing presence in the soccer industry. Frontiers in Sports and Active Living, 5, 1156601. https://doi.org/10.3389/fspor.2023.1156601 Gong, H., & Watanabe, N. M. (2025). The star effect of Lionel Messi on secondary market ticket prices in Major League Soccer. Journal of Sport Management, 40(3), 207 and following. https://doi.org/10.1123/jsm.2025-0019 Lawson, R. A., Sheehan, K., & Stephenson, E. F. (2008). Vend it like Beckham: David Beckham's effect on MLS ticket sales. International Journal of Sport Finance, 3(4), 189 to 195. Quansah, T. K., Buraimo, B., & Lang, M. (2024). Determining the price of football: An analysis of matchday ticket prices in the English Premier League. European Sport Management Quarterly, 24(3), 764 to 784. https://doi.org/10.1080/16184742.2023.2183967 Rewilak, J. (2023). The designated player policy rule and attendance demand in Major League Soccer. Journal of Sports Economics. https://doi.org/10.1177/15270025221134234 Rosen, S. (1981). The economics of superstars. American Economic Review, 71(5), 845 to 858. Sung, H., & Mills, B. M. (2018). Estimation of game level attendance in Major League Soccer: Outcome uncertainty and absolute quality considerations. Sport Management Review, 21(5), 519 to 532. https://doi.org/10.1016/j.smr.2017.12.002 Tenorio, P. (2026). The Messi effect: How the global legend changed the future of American soccer. St. Martin's Press. Wahl, G. (2009). The Beckham experiment: How the world's most famous athlete tried to conquer America. Crown Publishers. Warren, C. J., & Ross, S. D. (2011). Beyond Beckham: The designated player rule in Major League Soccer. International Journal of Sport Management, 12, 208 to 220. Watanabe, N. M., Imbrogno, C. T., & Mills, B. M. (2024). Superstars really are scarce: Shohei Ohtani and baseball attendance. Journal of Sport Management, 38(5), 340 to 352. https://doi.org/10.1123/jsm.2023-0155

This article examines how the arrival of Lionel Messi at Inter Miami CF in July 2023 functioned as the decisive catalyst that moved American soccer from a localized, niche product into the global mainstream sporting consciousness. Using a qualitative, theory-informed case study design built on secondary data (league and club performance records, publicly reported audience and attendance figures, commercial disclosures, and international press coverage between 2023 and 2026), the study traces three connected shifts: the transformation of global viewership patterns for Major League Soccer, the internationalization of media coverage of a league that had long been ignored outside North America, and the cultural assimilation of soccer within the United States. The analysis is framed through #globalization and #glocalization theory, the media-sport-culture complex, and theories of #celebrity_capital and #superstar_effect. Findings indicate that Messi did not create demand for soccer in the United States, since demographic, participation, and immigration trends had been building that demand for decades. Instead, he acted as an accelerator that converted latent interest into measurable, monetizable, and globally visible consumption. The article shows that the #Messi_effect was not a purely sporting phenomenon but a media-platform phenomenon: it depended on the coincidence of a singular athlete with a global, borderless streaming contract, a revenue-sharing contract structure, and a country preparing to co-host the 2026 FIFA World Cup. The article also identifies the structural risks created by this model, including dependency on one athlete, competitive imbalance, and the fragility of star-led growth. The conclusion argues that Messi's tenure represents a rare case of a single individual restructuring the symbolic position of an entire national sporting field. Keywords: Lionel Messi; Major League Soccer; globalization of sport; sport media; streaming platforms; cultural assimilation; superstar effect; American soccer 1. Introduction For most of its modern history, professional soccer in the United States has been described in the language of failure and delay. Scholars and journalists alike have asked why the world's most popular sport never captured the American imagination the way baseball, basketball, and gridiron football did. The question itself carries an assumption: that #soccer_in_America is an outsider, a game that belongs to other people, imported and never fully absorbed. On 15 July 2023, that assumption began to break down in public view. Lionel Messi, the most decorated player in the history of the men's game, signed with Inter Miami CF, a club that was sitting at the bottom of the standings in #Major_League_Soccer. The transfer was not a normal transfer. It was a #media_event with a global audience, a commercial experiment, and a cultural argument all at once. Within days, a league that had spent almost thirty years fighting for attention inside its own borders was being discussed on television and in newspapers from Buenos Aires to Bangkok. This article treats that moment, and the three seasons that followed it, as a case study in the #globalization of a national sporting market. The central claim is straightforward: Messi's tenure in MLS served as the definitive catalyst that shifted American soccer from a localized, niche market into the global mainstream sporting consciousness. The word "catalyst" is used deliberately. A catalyst does not create a reaction from nothing. It speeds up a reaction that the underlying conditions already permit. The United States already had a large Hispanic and Latino population with deep soccer literacy, a huge youth participation base, a growing audience for European leagues, and a media industry hungry for live rights. What it lacked was a single, unignorable focal point that could pull all of those latent elements into one visible market. Three themes organize the analysis. The first is the shift in #global_viewership. Before 2023, MLS was watched almost entirely by North Americans. After 2023, its most important matches were consumed across continents, in part because the league's streaming contract had no territorial blackouts. The second theme is #international_media_coverage. Outlets that had never sent reporters to a regular-season MLS fixture began covering Inter Miami as a matter of routine, and the language used to describe the league shifted from condescension toward serious analysis. The third theme is #cultural_assimilation: the process by which soccer stopped being framed as a foreign or immigrant sport in the United States and started to be treated as a normal part of the domestic sporting diet. The study contributes to three literatures. To the sociology of sport, it offers a contemporary case of how #sport_migration by a single elite athlete can reposition an entire league within the global sporting hierarchy. To #media_studies, it demonstrates how the #platformization of live sport rights changes the geography of an audience, since a streaming contract with global reach removes the territorial limits that traditionally kept domestic leagues domestic. To the study of celebrity and branding, it provides a rare natural experiment in which the #celebrity_capital of one person was contractually fused to the commercial performance of a league, a technology company, and an apparel manufacturer at the same time. A word on scope is necessary. This article is not a celebration of an athlete, and it is not a defence of MLS. It is an attempt to explain a rapid change in the position of a national sporting field within a global hierarchy, using a case in which the causal mechanism is unusually visible. The article is equally interested in the limits of that change: in the parts of the league that did not benefit, in the numbers that cannot be trusted, and in the strong possibility that a great deal of the value created remains attached to one man rather than to the institutions that host him. A good case study of a success story should be able to explain how the success might unravel, and Section 6 attempts exactly that. The article proceeds as follows. Section 2 reviews the relevant literature. Section 3 sets out the theoretical framework. Section 4 explains the methodology and data. Section 5 presents the findings across seven analytical themes. Section 6 discusses the implications, including the risks of star-dependent growth. Section 7 addresses limitations. Section 8 concludes. 2. Literature Review 2.1 The superstar effect in sport economics and sport management The idea that a small number of performers can capture a disproportionate share of attention and revenue is well established. In sport, the #superstar_effect is usually measured through attendance, television ratings, merchandise, and ticket prices. Studies consistently find that the presence of a star raises consumer demand for both live attendance and broadcast consumption, and that this effect can spill over to matches the star is not playing in, because the star raises the salience of the entire competition. Recent work has applied this logic directly to the Messi transfer. A 2025 study published in the Journal of Sport Management used secondary-market #ticket_demand data rather than reported attendance, and found that Messi's arrival raised prices for Inter Miami home matches by roughly 1,113 to 1,237 percent, and for Inter Miami away matches by roughly 410 to 477 percent, during the 2023 season. The same study found that the spillover to matches not involving Inter Miami was uneven, with several clubs showing insignificant or even negative price changes at home. This is an important nuance that the popular narrative usually flattens: the star lifted the league's ceiling far more than he lifted its floor. Parallel research on the Saudi Pro League has shown that a burst of star signings can generate a sharp, measurable rise in global public attention toward a league that previously sat on the periphery of the football world system (Mutz, 2024). That work is useful here because it separates two things that are often confused: attention and legitimacy. Attention can be bought quickly. Legitimacy, in the sense of being taken seriously as a competitive and cultural product, takes longer and may not follow at all. 2.2 Sport, media, and the platform economy The second literature concerns the reorganization of sport broadcasting by technology companies. Research on the entry of large technology firms into soccer has documented a shift from territorially fragmented broadcast deals toward global, direct-to-consumer distribution (Fakataulavelua, Lang, & Moulard, 2023). The MLS agreement with Apple, announced in 2022 and beginning with the 2023 season, is the clearest example in world football of a single platform holding worldwide rights to every match of a league. This matters for the present study because it changes the unit of analysis. Under a traditional model, a domestic league sells domestic rights to domestic broadcasters and separately sells international rights territory by territory. Highlights are geo-blocked. Audiences are fragmented. Under the #streaming model adopted by MLS, the same product is available everywhere at once, and the league's social clips can circulate without territorial restriction. Research on the adoption of over-the-top services has emphasized convenience, price, and content exclusivity as drivers of subscription behaviour (Mulla, 2022), but it has paid less attention to the role of a single human being as the trigger for mass sign-up. The Messi case supplies exactly that. Work on failures in the sports media business is a useful counterweight (Feuillet, Alem, Durand, Terrien, & Scelles, 2023). It reminds us that media rights valuations can collapse when subscriber growth does not follow the projections, and that a rights holder who overpays for a league without a compelling narrative is exposed. The Messi transfer can therefore be read as a rights-protection strategy as much as a sporting one. There is a further point in this literature that is often missed. The move from broadcast to platform does not only change who distributes sport; it changes what counts as evidence about sport. Traditional television audiences in the United States are measured by an independent third party using a standardized panel. Streaming audiences are not. When a platform or a league reports a viewership figure, it is reporting a number that it has defined, collected, and chosen to publish. Scholars who rely on such #audience_metrics without qualification risk mistaking a marketing claim for a measurement. This is not a reason to ignore the figures. It is a reason to read them as directional signals rather than as precise quantities, and it is the methodological position adopted throughout this article. 2.3 Soccer and American exceptionalism A long tradition in the sociology of sport treats the United States as a special case, sometimes described as sporting #American_exceptionalism. The core argument is that the American sport space was already crowded by the time soccer tried to enter it, and that the professional class of American sport was consolidated around baseball and gridiron football before soccer could establish itself. Historical scholarship has complicated this picture. Work on the early game shows that soccer was played, organized, and followed in American cities far earlier and far more widely than the standard narrative allows (Bolsmann & Kioussis, 2021). The sport did not fail to arrive; it failed to be recorded as American. More recent collections have documented the sport's contemporary position across media framing, gender, ethnicity, immigration, and regional identity, and have argued that American soccer should now be studied as a mature and internally diverse field rather than as a permanent failure story (Kassing, 2026). Parallel to this, research on Hispanic and Latino sport fandom in the United States has repeatedly found higher rates of passionate engagement with soccer than in the general population, and has argued that this population is central to the economics of the American sport industry rather than peripheral to it. Studies of Latina fans in particular have shown that these audiences are underrepresented in both marketing and scholarship despite their commercial significance. This literature is essential for understanding the Messi case, because Inter Miami sits in a metropolitan area where Spanish is a dominant public language and where Latin American football culture is not an import but a native condition. 2.4 Athlete brands, fandom, and social media The fourth literature concerns how athletes build and monetize personal brands, and how fans attach to individuals rather than to clubs. Research on athlete brand image has shown that performance, marketable lifestyle, and attractiveness all feed #fan_identification and loyalty (Mahmoudian, Sadeghi Boroujerdi, Mohammadi, Delshab, & Pyun, 2021; Magano, Szczygiel, & Au-Yong Oliveira, 2024). Endorsement research has found that a sport celebrity of sufficient stature can move the profitability of the brands attached to him, with Messi cited as a leading example (Shezi, 2025; Wang, 2024). Directly relevant is work analyzing the social network reflections of star transfers involving Messi and Cristiano Ronaldo, which found that fan attention travels with the individual and only partially transfers to the receiving club (Hayat, Samuel-Azran, Laor, & Galily, 2024). Research on clubs and players competing for fan loyalty has reached a similar conclusion (Merten, Reuland, Winand, & Marlier, 2024). This raises the central open question of the present study: when a star of Messi's magnitude joins a weak club in a peripheral league, does the audience stay with the player, or does some of it convert into durable attachment to the club, the league, and the sport? 2.5 The gap The existing literature covers the economics of stars, the platformization of rights, the history of American soccer, and the mechanics of athlete branding. What it does not yet do is bring these together into a single sociological account of how one athlete, one platform, and one national market interacted over a defined period to reposition a league inside the global sporting hierarchy. This article addresses that gap. 3. Theoretical Framework 3.1 Globalization, glocalization, and the sporting periphery Global sport can be understood as a system with a core and a periphery. The core is occupied by the major European leagues, which command the largest audiences, the highest wages, and the strongest symbolic authority. Everything else, including MLS, has historically been peripheral: a place where players go before they are ready for Europe or after they are finished with it. The concept of #glocalization is useful here because it rejects the simple story of a #global_culture flattening local difference. Instead, global forms are always adapted to local conditions. American soccer is a clear example. MLS imported the global game but wrapped it in American institutional forms: a single-entity ownership structure, a salary cap, a draft, no promotion or relegation, and a playoff system rather than a pure league table. Research on fan responses to playoff formats in MLS shows that these American structures are not cosmetic; they shape demand in measurable ways (Jung, Paek, & Sung, 2024). The Messi case is a #glocalization event in reverse. Rather than the global game adapting to America, an American league adapted its rules and its money to accommodate a global icon, and in doing so pulled itself closer to the core of the world system. 3.2 The media-sport-culture complex A second frame treats sport, media, and commerce as a single interlocking complex rather than three separate spheres. Under this view, a sporting event does not simply happen and then get reported. It is produced from the start as media content, designed for circulation, and valued according to the audience it can command. Editorial work on spectator sport and fan behaviour has stressed that the modern fan experience is mediated through screens more often than through stadiums (Galily, Pack, & Tamir, 2024). Applied here, this frame predicts that the significance of Messi's move would be determined less by what happened on the field than by how it was distributed. That prediction is testable, and Section 5 tests it. 3.3 Celebrity capital and parasocial attachment #Celebrity_capital refers to the accumulated recognition value of a person, which can be converted into economic, symbolic, and even political resources. Messi's celebrity capital was built over two decades in Europe and was crowned by the 2022 FIFA World Cup, an event that gave him the one credential he had lacked. He arrived in the United States with a stock of recognition that no American soccer institution could have generated on its own. The mechanism by which this capital transfers to an audience is often #parasocial_relationships: the one-sided bonds that fans form with public figures through repeated mediated exposure. In a #social_media environment, these bonds are maintained daily rather than weekly, and they follow the individual across institutional boundaries. This explains why a fan in Indonesia or Morocco with no prior interest in American club soccer might subscribe to a streaming service to watch a mid-table fixture in Fort Lauderdale. 3.4 Conceptual model Combining these frames yields a four-stage model of catalytic globalization, which structures the findings: Preconditions. A latent domestic market exists (demographics, participation, immigration, prior World Cup exposure) but is not converted into consumption. Catalyst. A figure of extreme celebrity capital enters the market under contractual terms that align his interests with those of the league's commercial partners. Amplification. A borderless distribution platform and a global social media apparatus convert the catalyst's attention into measurable, geographically dispersed consumption. Institutionalization. Some portion of the new attention is converted into durable structures: sponsorship, stadium investment, broadcast deals in new territories, sporting credibility, and shifts in cultural framing. The rest evaporates. The empirical question is how much of stage 3 becomes stage 4. 4. Methodology 4.1 Research design This study uses a qualitative, interpretive single-case design grounded in #sport_sociology and #media_studies. The case is bounded as the period from June 2023, when Messi announced his intention to join Inter Miami, to the first half of 2026, which covers three MLS seasons, one MLS Cup title, one FIFA Club World Cup appearance, a contract extension through 2028, and the opening phase of a World Cup year in North America. A #case_study design is appropriate because the phenomenon is, by definition, singular. There is no second Messi and no second case of a league of this profile acquiring an athlete of this magnitude while simultaneously holding a global, blackout-free streaming contract. The aim is analytic generalization to theory rather than statistical generalization to a population. 4.2 Data sources The study draws on publicly available secondary data of five kinds: Sporting records: league and club competition results, individual awards, goal and assist totals, and playoff outcomes for the 2023, 2024, and 2025 MLS seasons. Audience data: league-reported viewership figures for regular season, playoff, and final matches; reported subscription behaviour around Messi's debut; and reported international distribution arrangements. Attendance and ticketing data: league and club attendance reports, records set at individual venues, and published academic analysis of secondary-market ticket prices. Commercial data: publicly reported elements of the contract structure, including revenue-sharing arrangements with the league's media and apparel partners, club valuation and revenue estimates, and social media follower growth. Media texts: international and domestic coverage of the transfer and of subsequent matches, used to trace changes in framing rather than to establish facts. 4.3 Analytical procedure Data on #media_sport were organized chronologically and then coded thematically against the four-stage conceptual model. Codes were developed both deductively, from the theoretical framework, and inductively, from repeated patterns in the material. Seven themes were retained for presentation because each is supported by more than one class of evidence. Wherever a figure is reported by a party with a commercial interest in that figure, this is flagged in the analysis. This is a serious methodological issue in contemporary sport media research. Streaming platforms are not subject to the same independent measurement regime as traditional television, so the numbers that reach the public are frequently the ones the rights holder chooses to release. The findings below therefore treat direction of travel as more reliable than absolute magnitude. 4.4 Validity and ethics Triangulation across independent data classes, a standard safeguard in #qualitative_research, is used to guard against reliance on any single promotional source. Where sources conflict, the conflict is reported rather than resolved by preference. The study uses only public information about a public figure acting in a public professional capacity, and no human participants were involved. 5. Findings 5.1 The starting condition: a last-place club in a peripheral league The baseline matters. When Messi's move was announced in June 2023 and completed in July, Inter Miami CF was not a glamorous destination in sporting terms. The club, founded as an expansion franchise and co-owned by David Beckham along with the Mas brothers, was bottom of the Eastern Conference and had never won a trophy. It played in a temporary stadium in Fort Lauderdale with a capacity of around 18,000, a figure that would embarrass most clubs in Europe's second tiers. Its #Instagram following stood at roughly one million. The league around it was similarly modest in global terms. MLS was healthy domestically by its own standards, with stable attendance and expanding franchises, but it was invisible in the global conversation. Its matches were not analysed on international television. Its players were not household names outside North America. In the world system of football, it was #periphery. This starting condition is analytically valuable. It provides an unusually clean baseline against which to measure change, and it strengthens the causal story. If Messi had joined an already-glamorous club in an already-visible league, disentangling his effect would be far harder. 5.2 The signing as a global media event The announcement itself functioned as a #media_event in the classic sense: an interruption of routine, broadcast live, organized around a single figure, and consumed simultaneously across the world. It was not a press conference so much as a global broadcast moment. Three features of the deal made it structurally different from an ordinary transfer, and these features are the mechanism through which the catalyst operated. First, the contract was reported to be worth up to roughly 150 million dollars across two and a half years, combining salary, signing bonus, and an option on equity in the club. The equity option is important. It converted Messi from an employee into a stakeholder, aligning his incentives with the long-run value of the franchise rather than with his weekly output. Second, and more novel, the deal included #revenue_sharing arrangements with the league's commercial partners. Messi was reported to share in new subscription revenue generated for the league's streaming partner and in incremental apparel sales generated for the league's kit supplier. Industry lawyers described the streaming component as unprecedented in American professional sport. No player in the major North American leagues had previously been given a direct share of a media partner's subscriber growth. Third, the deal was made possible by a league willing to bend its own rules. MLS is built on cost control: a salary cap, a single-entity structure, and designated player exceptions. Accommodating Messi required the league and its partners to construct a payment architecture that sat largely outside the standard player contract. Of a total package later described by club ownership as being in the range of 70 to 80 million dollars per season, only around 20 million was guaranteed through the standard MLS contract. The sociological point is that this structure made the star and the platform financially interdependent. Messi had a direct interest in driving subscriptions. The platform had a direct interest in promoting Messi. The apparel partner had a direct interest in the same. The result was a coordinated commercial machine rather than a simple employment relationship. 5.3 Streaming, subscriptions, and the platform economy The #Apple_TV partnership is the hinge of the whole case. MLS had signed a ten-year global agreement with Apple beginning in the 2023 season, reported at approximately 2.5 billion dollars, under which every match was available worldwide with no blackouts. That structure had been criticized before Messi arrived, because a paywall around an unglamorous product is a hard sell. Messi's debut, against Cruz Azul in the Leagues Cup on 21 July 2023, changed the calculation immediately. Subscription analytics reported by the financial press indicated that more than 110,000 new subscriptions to the league's streaming pass were taken out on the day of that single match, against roughly 6,000 the day before. That is not a gradual lift. It is a step change produced by one person on one evening. Analysts noted at the time that sport had always been star-driven but had never before produced a subscriber bump of that shape. The league subsequently reported that subscriptions had more than doubled in the weeks after his arrival, and the platform's leadership publicly credited the signing with helping to beat internal targets. Two structural consequences follow. First, the global rights architecture meant that this new audience was not confined to the United States. A subscriber in Lagos, Jakarta, or Lima could watch the same match at the same time. The league's highlight clips could circulate on #social_media without the territorial restrictions that constrain most leagues. Messi's first goal for the club, a late free kick, was reported to have generated over 200 million social video views. A domestic league had acquired a genuinely global distribution surface, and then acquired the one player capable of saturating it. Second, the platform relationship deepened rather than stabilized. By the 2026 season, the league and Apple had restructured their agreement so that all matches were included within the general Apple TV subscription rather than sitting behind a separate league-specific pass. The league reported that through the first three months of the 2026 season, average viewership was up 62 percent year on year, with an average of roughly 7.9 million live match viewers per week when international distribution and linear partners were included. Opening weekend of 2026, headlined by Inter Miami's visit to Los Angeles, drew a reported 9.7 million live viewers across linear and streaming platforms, a 59 percent year-on-year increase. These figures require careful handling, and this is where methodological honesty matters. The league's aggregate viewership numbers combine global streaming with international linear simulcasts, which is not comparable to the domestic television measurement traditionally used in the United States. They are also released selectively by parties with an interest in the result. Part of the 2026 increase is plainly attributable to the removal of the separate paywall, not to Messi. What can be said with confidence is that the direction of travel is upward, that the largest single-match audiences cluster around Messi fixtures, and that the league's own executives attribute a substantial share of growth to the change in distribution model that Messi's presence made commercially viable in the first place. 5.4 Global viewership and the internationalization of coverage The clearest evidence of a shift in #global_viewership comes from the 2025 MLS Cup final. Inter Miami defeated Vancouver Whitecaps 3-1 at Chase Stadium in December 2025. The match reportedly drew around 4.6 million viewers, with fans in more than 100 countries able to watch on the league's streaming partner without blackouts, and additional audiences of over 3.6 million through broadcasters in Canada and Mexico. The final also drew the youngest audience in the history of the fixture, with a reported 70 percent of the streaming audience under 45. Consider what that means. A domestic championship game in a league that, five years earlier, was barely discussed outside North America, was now a globally distributed event with a global audience and a demographic profile that any advertiser would envy. The postseason as a whole averaged around 711,000 viewers per match, a 23 percent rise on the previous year. Alongside audience numbers, the character of #international_media_coverage changed. Before 2023, foreign coverage of MLS was episodic and usually framed around novelty: an ageing European star, an unusual stadium, a strange playoff rule. After 2023, the coverage became routine and evaluative. Argentine, Spanish, English, and Latin American outlets began covering Inter Miami as a matter of course, with regular match reports, tactical analysis, and transfer speculation. Global governing bodies produced their own editorial content assessing the meaning of Messi's American period. The framing shifted with the coverage. The condescension did not disappear, but it was joined by a serious register. Competitive-strength indices began to place MLS considerably higher than before. The league's own executives began to talk about a global rather than a domestic audience, and one club executive captured the change by saying that the club was now operating on an international level and that the sport in Miami was now football rather than soccer. That sentence is a small but revealing piece of sociological data: it is a claim about identity, not about business. 5.5 Attendance, ticket markets, and the road-show economy If streaming globalized the audience, the ticket market localized the shock and spread it across the country. The academic finding is the most reliable evidence available. Secondary-market prices for Inter Miami home fixtures rose by more than 1,100 percent, and for away fixtures by more than 400 percent, following the transfer. Journalistic reporting from the period is consistent with this: single-match tickets that had traded for tens of dollars were trading for hundreds, and premium packages for thousands. The away-match effect is the sociologically interesting one. Because MLS teams host Inter Miami on a rotating basis, the club functioned as a travelling spectacle. Clubs moved fixtures to larger venues to accommodate demand. Sporting Kansas City relocated a match against Inter Miami to Arrowhead Stadium and drew a crowd of 72,610, a club record and one of the largest standalone crowds in league history. The New England Revolution set their own club record for the same reason. Chicago reported that gameday revenue from a single Inter Miami visit matched the income of all its other home matches combined. League-wide, the effects were real but uneven. MLS reported #attendance up sharply in 2024, with 25 of 29 clubs level or higher than the prior year, and the league explicitly named the Messi factor as one of three drivers alongside consistent Saturday scheduling and general growth in the sport. By 2026, the league was averaging around 22,109 fans per match and reported the youngest average fan age of any major North American men's league at 39.6 years. Opening weekend 2026 produced the highest single-weekend attendance in league history, headlined by a crowd of 75,673 at the Los Angeles Coliseum. But the academic evidence cautions against a simple story. The spillover to matches not involving Inter Miami was inconsistent, with several clubs seeing no significant price change or even declines. This is the empirical signature of a star effect rather than a sport effect: the star raises the value of the events he touches, and the value of the league as a brand, without necessarily raising the value of every constituent product. Any honest account of the #Messi_effect must hold both facts at once. 5.6 From spectacle to sporting legitimacy Attention is not the same as legitimacy, and this is where the case becomes genuinely unusual. The Saudi comparison is instructive: heavy investment in stars produced a spike in global attention, but the competitive credibility of the league remained contested. In the MLS case, the sporting record did eventually follow the spectacle. The #trophies came in sequence. Inter Miami won the #Leagues_Cup in 2023, within weeks of Messi's debut, the first trophy in club history. They took the #Supporters_Shield in 2024 with a league-record points total, and Messi was named the league's Most Valuable Player. In 2025 the club reached the round of 16 at the expanded FIFA Club World Cup, becoming the first MLS side to reach the knockout stage of that competition and the first club from the United States to win a match in it. Then, in December 2025, they won the #MLS_Cup, defeating Vancouver 3-1, with Messi named the final's most valuable player. The individual record in 2025 was extraordinary by any standard. Messi won the Golden Boot with 29 goals in 28 regular-season appearances and added 19 assists for 48 goal contributions. He became the first player in league history to be named Most Valuable Player in consecutive seasons, and the first to record ten multi-goal games in a single campaign. In the playoffs he set a new record for goal contributions in a single postseason. Across all competitions in 2025 he recorded 74 goal contributions in 49 appearances. He then signed an extension through 2028, positioning him to open the club's new permanent stadium. This sequence matters theoretically. It closes the gap between attention and #sporting_legitimacy that the Saudi case leaves open. A neutral observer in 2023 could reasonably have dismissed the move as a lucrative retirement. By 2026, that reading is untenable. The player performed at a level that would have been elite in any league in the world, and the club converted his presence into the two most meaningful domestic trophies available to it. The narrative available to international media was no longer "great player winds down in a weak league" but "great player wins a league that is getting stronger." 5.7 Cultural assimilation: from immigrant sport to American sport The final and most sociologically important theme is #cultural_assimilation. Here the evidence is softer than in the audience and ticket data, but it is consistent across several indicators. The first indicator is geography and language. Miami is not a neutral American city. It is a Latin American capital in many respects, with Spanish functioning as a public language and with deep familial and media ties to Argentina, Colombia, Venezuela, and Cuba. Messi did not arrive as a foreign curiosity in Miami. He arrived in a place where his cultural repertoire was already legible. The club's chosen iconography, from its pink shirts to its bilingual communications, positioned it as a hybrid object: American in ownership and league membership, Latin American in idiom. The second indicator is the composition of the audience. Research on Hispanic and Latino fandom in the United States has repeatedly shown a higher intensity of soccer engagement in this population than in the general public, and recent industry analysis has argued that Latino fans represent one of the largest sources of growth in the American sport economy. #Latino_fandom is not a marginal segment. It is a foundation. Messi's arrival made that foundation commercially visible in a way that decades of marketing had not. The third indicator is age. The league's reported average fan age of 39.6 years, the youngest among the major North American men's leagues, and the reported skew of the 2025 final audience toward viewers under 45, both suggest a fanbase that is being built rather than inherited. This is the profile of a growing cultural form, not a legacy one. The fourth indicator is framing. Cultural assimilation can be observed in language. Before 2023, American media coverage of MLS was heavily marked by defensiveness and by comparison with Europe. After 2023, coverage increasingly treated the league on its own terms. The sport is discussed in American mainstream outlets without the ritual apology that once accompanied it. Public health scholarship has begun to treat recreational soccer as an ordinary American population-level activity worth investing in (Oliva-Lozano, Chiampas, Cost, Sullivan, & Lobelo, 2024). These are the small signs by which a sport stops being foreign. The fifth indicator is institutional investment. A new permanent stadium at Miami Freedom Park, planned as the centrepiece of a large mixed-use district, represents the kind of long-horizon capital commitment that does not get made for a passing fad. Club revenue was reported to have risen from roughly 50 to 60 million dollars in 2022 to well over 200 million by the mid-2020s, and the club's Instagram following grew from about one million before the signing to figures rivalling or exceeding those of established franchises in the older American leagues. #franchise_valuation across the league rose, with the average club worth reported at 767 million dollars by 2026. None of this proves that soccer has become an American sport in the way that basketball is. It does show that the terms of the argument have changed. 5.8 Merchandise, sponsorship, and the commercial architecture of the transfer The commercial dimension deserves separate treatment, because it is where the fusion of athlete, club, league, and corporate partner is most visible. The clearest early signal came from #jersey_sales. The Inter Miami shirt bearing Messi's name became, according to the league's apparel partner, the fastest-selling jersey in the first twenty-four hours of release that the company had recorded. It was also the most expensive shirt on the manufacturer's site, priced at roughly double the cost of the Argentina national team shirt from the World Cup-winning campaign of the previous year. The sociological reading of that price differential is worth pausing on. Consumers were paying a premium not for national identity, which is the traditional engine of football merchandise demand, but for proximity to an individual. The shirt was a Messi artefact that happened to be pink. Sponsorship followed the same logic, and here the club had prepared in advance. Reporting on the club's commercial structure indicates that long-term sponsorship agreements signed before Messi's arrival contained escalator clauses that would automatically increase the sponsorship fee if the club signed a player who had won at least five Ballon d'Or awards. Only two players in the world met that condition. The clause is a remarkable piece of institutional anticipation: the club had written the possibility of a global superstar into its commercial contracts years before the superstar was available. When Messi signed, a large part of the club's revenue base repriced itself automatically. The result was a step change in the club's finances. Revenue reported at roughly 50 to 60 million dollars in 2022 had, by the middle of the decade, been reported at more than 200 million, a rise of several hundred percent in a period of three years. Club valuation crossed the billion-dollar mark. Across the league, the average franchise was reported to be worth 767 million dollars by 2026. The #revenue_sharing structure knitted these actors together. Because Messi participated in the upside of the streaming partner's subscriber growth and the apparel partner's incremental sales, every party in the chain had a financial reason to promote every other party. This is not how player contracts normally work. In the standard model, a club pays wages and captures whatever commercial upside follows. Here, the athlete was made a co-investor in the ecosystem, and the ecosystem was made a co-investor in the athlete. For students of the #subscription_economy, this is the single most portable lesson of the case. Platforms buying live sport rights are buying a promise about future subscriber behaviour. They therefore have a direct interest in the leagues they buy improving their own content. What the Messi deal demonstrates is that a platform can move from passive rights holder to active participant in talent acquisition, and that a league short of cash can use its media partner's balance sheet, indirectly, to buy the star it could not otherwise afford. Whether that arrangement is healthy for competitive balance is a separate question, and a troubling one. 5.9 Participation, youth, and the grassroots The final layer of assimilation is participation. Media consumption and cultural belonging are related but not identical, and a sport becomes native to a country when children play it without thinking of it as foreign. Here the evidence predates Messi and does not depend on him. The United States has had a very large youth soccer participation base for decades, one of the largest in the world in absolute terms. Public health scholarship has recently argued that recreational soccer in the United States should be treated as a serious instrument of population health, and has anticipated that the 2025 Club World Cup and the 2026 World Cup will further stimulate participation across the region (Oliva-Lozano et al., 2024). That framing is itself evidence of assimilation. A sport is treated as national infrastructure only when nobody thinks of it as an import. What Messi's presence appears to have changed is not the number of children playing but the aspirational structure around them. For most of the history of American soccer, the ambitious young player looked outward: the goal was Europe, and the domestic league was a waystation. #youth_participation was disconnected from professional aspiration at the highest level. A domestic league that produces a world champion holding the greatest player in history as its captain, and that opens a purpose-built stadium in a major American city, offers a different aspirational geography. The professional summit is now visible from the domestic base. This claim should be held loosely. It is the least evidenced of the seven themes, and it is exactly the kind of proposition that requires reception research with players, parents, and coaches rather than inference from league data. It is included because the assimilation argument would be incomplete without it, and because it identifies the most useful direction for future work. 6. Discussion 6.1 Catalyst, not creator The thesis of this article is that Messi was the definitive catalyst of American soccer's entry into global mainstream consciousness. The findings support that claim, but they also require it to be stated precisely. Messi did not create the American #soccer_audience. That audience was assembled over four decades by immigration, by the 1994 and 1999 World Cups, by youth participation, by the growth of Spanish-language broadcasting, and by an entire generation of Americans who grew up following European clubs on cable and then online. The demographic and cultural preconditions were in place. What was missing was conversion: a reason for latent interest to become active, paid, visible consumption, and a reason for the rest of the world to look. Messi supplied that reason. He functioned as a focal point around which existing but scattered interest could organize. In the language of the conceptual model, stages 1 and 2 were separated by a gap that no marketing budget had been able to close, and celebrity capital of a sufficiently extreme magnitude closed it in a single week. This is why the counterfactual is worth stating. Without Messi, MLS in 2026 would very likely still be growing, because the underlying trends were positive. But it would be growing domestically, quietly, and on a timeline measured in decades. It would not be a league whose championship final is watched in more than 100 countries. 6.2 The star-platform complementarity The more original finding is that the catalyst worked because it was fused to a platform. This is the theoretical contribution the case makes most strongly. Consider the counterfactual again. If Messi had joined MLS in 2013 under the old, territorially fragmented broadcast model, his effect would have been real but bounded. Domestic ratings would have risen. Away crowds would have swelled. But a fan in Southeast Asia would have had no legal, convenient way to watch, and the highlights would have been geo-blocked. The Apple agreement removed those boundaries before Messi arrived. The league had built a global pipe with nothing global to push through it. Messi was the content that justified the pipe, and the pipe was the infrastructure that globalized the content. Neither would have produced the observed effect alone. The revenue-sharing contract structure formalized this complementarity, making the athlete a financial participant in the platform's growth. This suggests a general proposition for future research: in a platform era, the globalizing power of a sporting superstar is a function not only of his celebrity capital but of the territorial reach of the distribution contract he arrives under. #platformization and star power are multiplicative, not additive. 6.3 The risks of star-dependent growth An honest analysis must weigh the fragilities of this model, and there are several. The first is #star_dependency. A league whose global visibility rests on one athlete is exposed to injury, form, and age. Messi turned 38 in 2025. His extension runs through 2028. What happens afterwards is the central strategic question facing MLS, and the league's own commissioner has publicly described him in terms that concede the point. The second is #competitive_imbalance. The academic ticket-price evidence shows uneven spillover across clubs. Some benefited enormously from hosting Inter Miami; others saw little or nothing. A structure in which one club commands a disproportionate share of the league's attention and commercial upside sits uneasily with the cost-controlled, parity-focused model that MLS was built on. Research on competitive balance in other contexts warns that concentration of resources tends to be self-reinforcing (Gyimesi, 2024). The third is the measurement problem. The most impressive figures in this case come from parties who benefit from them. Streaming platforms do not submit to independent audience measurement in the way traditional broadcasters do. When a rights holder chooses which numbers to publish, flattering numbers become more likely to appear than troubling ones. Scholars working in this area should treat league-issued audience data as directional evidence, not as measurement. The fourth is the retention question, which is the one that will determine whether stage 3 becomes stage 4. Research on star transfers suggests that fan attention travels with the individual and only partially converts into attachment to the club or league. The 2026 opening weekend is instructive here: the record-breaking crowd came to see Inter Miami visit Los Angeles, and Inter Miami lost 3-0. Whether the people who tuned in for Messi return for a fixture without him is, at present, an open empirical question. The fifth is a risk to #talent_development. A model built on importing global celebrity can crowd out investment in domestic player production, and can reinforce the perception of the league as a destination for late-career stars rather than a producer of early-career ones. The counter-evidence is real, since the league has recently attracted players in their prime rather than only at the end of their careers, but the tension remains. 6.4 Comparison with the Beckham precedent and the Saudi model The case invites two comparisons. The #Beckham_precedent is the obvious one. David Beckham joined the LA Galaxy in 2007 under a deal that also included an option to purchase an expansion franchise, an option he later exercised to found Inter Miami. There is a genuine historical symmetry here: the club that signed Messi exists because of the contract that brought Beckham. But the differences are more instructive than the similarities. Beckham arrived before smartphones were ubiquitous, before streaming, and before social media in its current form. His effect was real but was channelled through traditional broadcast and print, both of which are territorially bounded. Messi arrived into an infrastructure built for global, instantaneous, borderless circulation. The #Saudi_Pro_League comparison is sharper. Both leagues used extreme financial packages to import global stars, and both saw an immediate spike in global attention (Mutz, 2024). The divergence is in what followed. Recent work on player brand image after transfers to Saudi Arabia suggests that moving to a peripheral league can carry reputational costs for the athlete. In the MLS case, by contrast, the sporting record eventually validated the move, and the transfer was widely read as culturally coherent rather than purely mercenary, in part because the destination was a country about to host the World Cup and a city with deep Latin American roots. Attention was converted into legitimacy. That conversion, not the initial spike, is the substance of the argument in this article. 6.5 The 2026 World Cup and the question of legacy The Messi period does not exist in isolation. It runs directly into the 2026 FIFA World Cup, co-hosted by the United States, Canada, and Mexico. This creates a compounding effect that no previous star signing enjoyed. The sequence matters. A generation of American consumers was introduced to elite soccer through Messi between 2023 and 2026, developed the habit of watching, and then encountered the largest World Cup ever staged in their own country. The tournament will provide a second, larger wave of exposure to an audience that has already been primed. Whether MLS can hold the attention that the tournament generates is the defining test of #legacy_effects. This is where the article's central concept earns its keep. A catalyst lowers the energy required for a reaction to proceed. It does not guarantee the reaction. The preconditions were necessary. The catalyst was decisive. The institutionalization is unfinished. 6.6 Implications for practice and policy Several practical implications follow from the analysis, and they are worth stating because sport management students and practitioners are among the intended readers of this article. For leagues, the lesson is that #media_rights architecture should be designed before the star is signed, not after. The reason the Messi effect travelled globally is that the pipe was already global. A league that signs a superstar while its rights remain territorially fragmented will capture a domestic bump and lose most of the international value. The sequence matters. For clubs, the lesson is anticipatory contracting. Inter Miami's escalator clauses show that commercial upside can be captured only if the contracts have been written to capture it. A club that signs a global star without having repriced its sponsorship inventory in advance will spend years renegotiating deals it could have written correctly in the first place. For platforms, the lesson is that content and talent cannot be separated. A rights holder who treats a league as a finished product to be distributed is exposed to the quality of that product. A rights holder who participates, financially and strategically, in the improvement of that product converts a passive risk into an active investment. This is a genuine change in the political economy of #sports_broadcasting, and it deserves close scrutiny from regulators as well as scholars. For leagues in the global periphery more broadly, from Asia to Africa to the Gulf, the case offers a template and a warning in equal measure. The template is that attention can be purchased and, under the right conditions, converted into legitimacy. The warning is that the conditions are demanding. They include a genuine domestic demand base, a distribution partner with global reach, a receiving city with cultural affinity for the athlete, and, critically, an athlete who is still capable of performing at an elite level. Remove any one of these and the model degrades into an expensive exhibition. For governing bodies preparing for the #World_Cup_2026, the implication is that the tournament arrives into a market that has already been warmed. The task is not introduction but retention. 7. Limitations Four limitations should be stated plainly. First, much of the quantitative evidence originates from parties with a commercial interest in it. League-issued viewership numbers, platform-issued subscriber commentary, and club-issued revenue estimates are all promotional artefacts as well as data. The study has attempted to compensate by triangulating across sources and by privileging peer-reviewed analysis where it exists, but the underlying measurement problem cannot be resolved from outside. Second, the study is a single case, and the causal claim rests on temporal coincidence and mechanism rather than on a controlled comparison. The 2026 removal of the separate streaming paywall is a clear confound for the 2026 viewership figures, and the approach of the World Cup is a confound for the entire late period. Third, the study analyzes production and distribution rather than reception. It infers audience meaning from behavioural traces such as subscriptions, attendance, and follower counts. It does not ask fans what the change meant to them. Survey and interview work is needed, particularly with Latino and young American audiences, who are the two populations most central to the assimilation argument. Fourth, the analysis is bounded at mid-2026. Messi's contract runs to 2028. The most important question, which is what happens to the audience when he stops playing, cannot yet be answered. Future research should pursue three lines: longitudinal audience retention studies tracking whether Messi-acquired subscribers persist; comparative work on the interaction between star signings and rights architecture across leagues; and reception studies examining how American fans, particularly Hispanic and Latino fans, describe the meaning of this period in their own words. 8. Conclusion This article set out to test a strong claim: that Lionel Messi's tenure in Major League Soccer was the definitive catalyst that shifted American soccer from a localized, niche market into the global mainstream sporting consciousness. The evidence supports the claim, with qualifications that make it more useful rather than weaker. The shift in #global_viewership is documented. A championship final in a league that was globally invisible in 2020 was watched in more than 100 countries in 2025, with a young audience and no territorial blackouts. Weekly viewership figures in 2026 are multiples of what they were three years earlier. The shift in #international_media_coverage is documented. MLS moved from a curiosity covered occasionally and condescendingly to a league covered routinely and seriously, with a rising position in competitive strength assessments and a club whose fixtures are now standing items in the sports press of several continents. The #cultural_assimilation of soccer in the United States is the least measurable and the most consequential of the three. The indicators point the same way: a young and growing fanbase, a Latino audience finally treated as central rather than peripheral, permanent stadium investment, rising franchise values, and a shift in the language used to talk about the sport. Three broader conclusions follow. The first is theoretical and concerns #celebrity_capital. The globalizing power of a sporting superstar in the platform era cannot be understood through celebrity capital alone. It is the product of celebrity capital and distribution reach. Messi's effect was as large as it was because he arrived in a league that had already sold its global rights to a single platform with no blackouts. The star and the pipe made each other. The second is sociological and concerns #symbolic_capital. This case demonstrates that the position of a national sport within a global hierarchy is not fixed by history or by culture. It can be moved, and it can be moved quickly, by the strategic deployment of symbolic capital. The story of American soccer as a permanent failure, a story told for a century, was undone in roughly three years. The third is a caution. Catalytic growth is fast, and fast growth is fragile. 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SHS Web of Conferences, 193, 01034. https://doi.org/10.1051/shsconf/202419301034 #Messi_Effect #Globalization_Of_Soccer #American_Soccer #MLS_Growth #Sport_Sociology #Media_Studies #Sports_Media #Global_Football #Inter_Miami_CF #Soccer_Culture #Sport_Globalization #Fan_Culture #Streaming_Sports #Sports_Marketing #World_Cup_2026

Sports economics has long treated the value of an athlete as a function of two things: what the athlete adds to team performance, and what that added performance adds to local revenue. The 2023 transfer of Lionel Messi to Inter Miami CF challenges that framing. Drawing on the reporting assembled in Paul Tenorio's book The Messi Effect: How the Global Legend Changed the Future of American Soccer, together with franchise valuation data, attendance records, streaming subscription figures, sponsorship estimates and peer reviewed studies of star power, this paper examines the economic anatomy of what has become known as the #Messi_Effect. The paper argues that Messi did not function as a conventional #marginal_revenue_product asset. He functioned as an #economic_engine whose #global_brand_equity was transferred, more or less intact, into a league that had never previously held an asset of that scale. Inter Miami moved from an estimated value of about 585 million dollars before his arrival to the most valuable franchise in Major League Soccer, above the 1 billion dollar line, with revenue rising from roughly 56 million dollars in 2022 to roughly 200 million dollars in 2025. His pink number 10 shirt became the best selling jersey in the league's retail history, stadiums sold out across the country, and subscriptions to the league's streaming product spiked on the day of his debut. Yet the paper also documents the limits of the phenomenon. Peer reviewed evidence shows that the spillover to matches not involving Inter Miami was uneven and in some markets negligible, and that valuation growth concentrated at the top of the league rather than spreading evenly. The conclusion is that the #Messi_Effect represents a genuine but partial #paradigm_shift: a demonstration that individual brand capital can now rewrite the financial trajectory of an entire league, and simultaneously a warning that such value is rented rather than owned, and that leagues which fail to convert it into institutional capacity will find it leaves with the player. Keywords: superstar economics; sports finance; franchise valuation; Major League Soccer; athlete branding; media rights; Lionel Messi; Inter Miami CF 1. Introduction For most of its modern history, the economics of professional team sport has rested on a fairly stable idea. A player is worth what he adds. He adds wins, wins add spectators and sponsors and television audiences, and the sum of those additions, discounted over the length of a contract, is the value of the player to the club. The idea is old, it is durable, and it works reasonably well for the overwhelming majority of athletes in the overwhelming majority of leagues. It is the reason clubs build analytics departments, the reason they argue over expected goals and win shares, and the reason a #salary_cap can be defended as a device for holding costs in line with the revenue that players actually generate. Then there are the cases the model does not handle well. In July 2023, Lionel Messi signed with Inter Miami CF, a club sitting last in the Eastern Conference of Major League Soccer, playing in a temporary stadium in Fort Lauderdale, and valued by industry estimates at somewhere near 585 million dollars. Within roughly thirty months, that same club had become the most valuable franchise in the league, worth about 1.45 billion dollars by one industry count and about 1.35 billion by another, with annual revenue near 200 million dollars, a new privately financed stadium, an #MLS_Cup title, and the best selling jersey in the world. No conventional reading of #marginal_revenue_product predicts that. Messi was thirty six years old when he arrived. He was, in strictly athletic terms, past the peak that made him famous. And yet the financial output attached to his presence exceeded what many entire clubs produce over a decade. This paper takes that gap seriously. It argues that the arrival of Messi in the United States exposed a structural change in how value is created in sport, and that the change is significant enough to be described as a #paradigm_shift. The claim is not that star power is new. Star power is one of the oldest observations in the economics of entertainment, and the literature on it is deep. The claim is narrower and, I think, more interesting. It is that the digital and global infrastructure of the 2020s allows a single athlete to carry an audience across borders and across leagues in a way that was not previously possible, and that this ability turns the athlete into something closer to a #media_property than a labour input. A club that acquires such an athlete is not simply buying performance. It is acquiring a distribution channel, a sponsorship magnet, a merchandising engine, and, crucially, a reason for a technology company to renegotiate the value of an entire league. Paul Tenorio's book, The Messi Effect: How the Global Legend Changed the Future of American Soccer, published in 2026, provides the most detailed narrative account of how this unfolded inside the club and inside the league. Tenorio, a senior writer at The Athletic, reports from both the locker room and the boardroom, and his central observation is one that this paper adopts and formalises: Messi in Miami was a story about the business of sport, and about how a player can be simultaneously an athlete and an #economic_engine. Tenorio also records something equally important, and less often quoted in the celebratory coverage. The league debated how to use the moment. Owners argued about roster rules, about spending limits, about whether the structure that had kept MLS financially disciplined was now the structure keeping it small. And the league, in the end, chose to postpone the biggest decisions. That tension is the analytical heart of this paper. A superstar can change the numbers on a balance sheet quickly. Changing an institution is slower, harder, and entirely optional. The #Messi_Effect is therefore best understood not as a single economic event but as a test: a natural experiment in whether a league can absorb an asset larger than itself. 1.1 Research questions This study is organised around four questions. First, what exactly changed in measurable financial terms after Messi's arrival, and how much of the change can reasonably be attributed to him rather than to trends already underway in American soccer? Second, through which economic channels did the effect travel? Ticketing, merchandise, media subscriptions, sponsorship, franchise valuation and #brand_equity all behaved differently, and treating them as a single lump obscures more than it reveals. Third, was the effect concentrated or distributed? A #superstar_externality is only a league level phenomenon if it lifts clubs other than the one paying the wages. The evidence on this point is more mixed than the headlines suggest. Fourth, is the shift durable? Messi is under contract into the late 2020s, but he is in his late thirties. If the value he created is entirely rented, then MLS has bought a fireworks display. If it is partially converted into infrastructure, media distribution, fan habits and youth participation, then the league has bought something closer to a foundation. 1.2 Contribution The paper contributes in three ways. It offers a structured economic anatomy of a case that has so far been discussed mostly in journalism and industry reports. It connects that case to the existing peer reviewed literature on star effects, which has quantified attendance and pricing responses but has rarely had access to an event of this magnitude in a mid tier league. And it proposes a framework, the superstar as platform model, that treats the elite athlete as an asset whose value derives from #audience_portability rather than from on field marginal product alone. 1.3 Structure Section 2 reviews the literature on superstars, star effects and athlete branding. Section 3 sets out the conceptual framework. Section 4 explains the method and the data. Section 5 describes the case, including the unusual architecture of the Messi deal. Section 6 presents the findings channel by channel. Section 7 discusses what the findings mean for theory, for #competitive_balance, and for the future of the league. Section 8 acknowledges limitations. Section 9 concludes. 2. Literature Review 2.1 Two theories of the star The economics of superstars begins with a simple puzzle. Why do small differences in talent produce enormous differences in reward? Two answers dominate the field. The first, associated with Sherwin Rosen's 1981 paper, holds that talent is imperfectly substitutable. Audiences do not want to watch two average performers instead of one great one, and modern technology allows the great one to serve a very large market at low marginal cost. Talent therefore scales, and the reward distribution becomes extremely skewed. The star is a #Rosen_star: genuinely better, and rewarded for it in a market that lets him sell to everyone at once. The second answer, associated with Moshe Adler, holds that #popularity can be self reinforcing even when talent is roughly equal. Consumption of art or sport is social. Knowing more about a performer makes watching that performer more enjoyable, and it is easier to accumulate knowledge about someone everyone else is already discussing. The star becomes an #Adler_star: a focal point sustained by shared attention rather than by measurable superiority. The distinction matters here because Messi in 2023 is an unusual hybrid. His talent remained exceptional but was no longer at its peak. His attention stock, however, was arguably at its highest point ever, having just won the 2022 FIFA World Cup. If the #Messi_Effect were purely a Rosen phenomenon, we would expect the financial response to track his on field production. It did not. The financial response was immediate, arriving before he had played a competitive minute in MLS, which is the signature of an #Adler_dynamic operating at global scale. 2.2 Star effects on attendance and demand A substantial empirical literature has tested whether stars actually move consumer demand. Work on the National Basketball Association has consistently found that the presence of a superstar raises attendance at both home and away venues, an effect often described as a #superstar_externality because the visiting club captures revenue it did not pay for. Related work has found that television audiences fall measurably when advertised stars are absent, which confirms that consumers are buying the individual and not only the contest. In football, the picture is more nuanced. Research on German and European leagues has distinguished between local heroes and international stars, finding that both matter but through different mechanisms. Jedelhauser, Flepp and Franck, writing in the Journal of Sports Economics in 2023, went further and showed that the popularity of first tier stars can overshadow the market value of very good second tier players, meaning that attention itself is a scarce resource that gets allocated unequally even among elite performers. Schreyer and Ansari's 2022 scoping review of stadium attendance demand research provides a useful map of how crowded and how methodologically varied this field has become. The most directly relevant recent study is by Schreyer and Singleton, published in Contemporary Economic Policy in 2025, which examined whether Cristiano Ronaldo raised attendance after joining Al Nassr in the Saudi Pro League. Their findings are striking and, importantly for this paper, they are quantified. Ronaldo filled roughly an additional twenty percent of seats in his own home stadium, roughly fifteen percent in stadiums he visited, and around three percent even in matches he did not play in. That last figure is the closest thing the literature has to a measured league level halo, and it is small. The lesson is that superstar effects are real, large where the star is physically present, and thin where he is not. 2.3 The Major League Soccer precedent MLS has been here before, on a smaller scale. The arrival of David Beckham at the LA Galaxy in 2007 prompted the creation of the #Designated_Player rule, which allowed clubs to sign a limited number of players outside the salary budget. Research on the Beckham period found a genuine but partly novelty driven effect on attendance and league marketing, one that softened after his departure. Rewilak, writing in the Journal of Sports Economics in 2023, examined the Designated Player rule directly and found that its effect on attendance demand is more modest and more conditional than the league's own marketing narrative implies. Jewell's earlier work on marquee players in MLS reached compatible conclusions. This literature supplies the appropriate baseline scepticism for the present case. MLS has repeatedly announced that a star will transform it. The question is whether Messi is different in kind or merely different in degree. 2.4 The athlete as a human brand A parallel body of research treats the athlete not as a labour input but as a #human_brand. Work in this tradition, including Anderski and colleagues in the Journal of Business Research in 2023, argues that athlete brands are now co created with audiences on digital engagement platforms rather than broadcast outward from clubs. Noh, Ahn and Anderson, writing in European Sport Management Quarterly in 2023, show how consumers form attachments to athletes that are independent of, and sometimes in tension with, the organisations that employ them. Recent work on transfers to the Saudi Professional League, published in European Sport Management Quarterly in 2025, tested whether moving to a less prestigious league damages a player's brand image. It found that the damage was smaller than expected and that some brand associations improved. The implication is significant for the present case: an elite athlete's brand equity is now league independent to a considerable degree. It does not evaporate when the athlete moves down the sporting hierarchy. That portability is precisely what makes the transfer of a global star into a mid tier league economically viable, and it is a comparatively new condition. 2.5 Franchise valuation and the media rights layer Franchise valuations in North American sport are driven less by profit than by expected future cash flows, media rights, stadium control, real estate and scarcity of ownership opportunities. A star player rarely appears explicitly in these models. The #Messi_Effect matters theoretically because it inserted a player into the valuation equation directly, through revenue, and indirectly, through the reappraisal of the league's media rights ceiling. Mutz, writing in Frontiers in Sports and Active Living in 2024, tracked global public attention toward the Saudi Pro League and found that high profile signings produced a measurable but partly transient rise in international interest. Attention, in other words, can be purchased. Whether it can be retained is a separate empirical matter. 2.6 The gap this paper addresses Three gaps emerge. First, the star effects literature is dominated by attendance and ticket price studies, with far less attention paid to #franchise_valuation, streaming subscriptions and sponsorship as transmission channels. Second, almost no study has examined a case where the star's brand scale exceeded the scale of the entire league he joined. Third, the literature has not adequately theorised what happens after the star leaves, which is the question that determines whether any of this constitutes a shift or merely a spike. 3. Conceptual Framework: The Superstar as Platform 3.1 From marginal product to audience portability The traditional model values a player as the discounted sum of the revenue his performance generates for one club in one market. Call this the #marginal_revenue_product model. It assumes that the audience belongs to the club, that the player rents it, and that the player's contribution is measured at the margin. The framework proposed here inverts that assumption. In the case of a genuinely global athlete, the audience belongs to the player. The club rents access to it. The player's value is therefore determined not by how much he improves the team but by how much of his existing audience he can carry across the boundary into the new context. I call this #audience_portability. Portability depends on several conditions, most of which did not exist twenty years ago. The athlete must own a direct channel to his audience, which social media provides. The league's product must be globally distributable without geographic blackouts, which streaming provides. The athlete's commercial partners must be able to activate globally, which multinational sportswear and technology firms provide. And the receiving league must be willing to restructure its own economics to accommodate an asset it cannot afford under existing rules, which is a governance decision rather than an economic one. When these conditions hold, the athlete functions less like an employee and more like a #platform. He arrives with an installed user base. The club becomes, in effect, an application running on that platform. 3.2 Four channels of transmission The framework identifies four channels through which #platform_value converts into money. The first is the direct gate channel: tickets, hospitality and matchday spending, at home and on the road. It is immediate, highly visible, and geographically bounded by where the player physically appears. The second is the merchandise and licensing channel. This is largely borderless. A jersey can be sold in Jakarta to someone who will never attend a match, and the sale is attributable almost entirely to the player rather than to the club. The third is the media and subscription channel. This is where the largest structural effects appear, because a streaming platform's subscriber base is a durable asset, and because media rights are the single largest input into league level valuation. The fourth is the sponsorship and valuation channel. Sponsors pay for attention. When attention rises, sponsorship inventory reprices. When sponsorship, gate and media all reprice at once, franchise valuation follows, and the effect compounds because valuation is a multiple of expected future flows rather than a snapshot of current ones. 3.3 The conversion problem The framework's central prediction is that the four channels decay at different rates once the player departs. Gate revenue collapses quickly. Merchandise revenue declines sharply but leaves a residue of brand awareness. Media subscriptions decay slowly if the platform has used the window to build habits and catalogue. Sponsorship and valuation decay slowest of all, provided the league has used the period to sign long term agreements and build permanent assets such as stadiums. This produces what I call the #conversion_problem. A league that receives a superstar has a limited window in which to convert transient attention into #permanent_capacity. The relevant policy question is not how much money Messi generated. It is how much of that money was invested in things that will still be there in 2032. 4. Methodology 4.1 Research design This study uses a single case design with embedded units of analysis. The case is Inter Miami CF and Major League Soccer between 2022 and 2026. The embedded units are the four transmission channels identified in Section 3. A single case design is appropriate here because the phenomenon is, by construction, singular. There is exactly one Messi transfer to MLS, and the value of studying it lies in its status as a critical case rather than in its representativeness. 4.2 Data sources The study draws on four categories of evidence. Documentary evidence comes primarily from Tenorio's 2026 book, which supplies the internal narrative of the deal and of the league's subsequent debates about roster rules. Financial and valuation data come from published industry estimates by Sportico and Forbes, which are the standard sources used in sports finance research when audited club accounts are not publicly available. These estimates are not audited, and this limitation is treated seriously in Section 8. Operational data on attendance, sellouts, jersey sales, sponsorship revenue and streaming subscriptions come from league announcements and from analytics firms including Antenna, whose subscription tracking of MLS Season Pass around the Messi debut is the most precise public evidence of the streaming response. Peer reviewed evidence comes from the star effects literature, and in particular from the 2025 Journal of Sport Management study of Messi's impact on secondary market ticket prices, which supplies the only rigorous causal estimates currently available for this specific event. 4.3 Analytical strategy The analysis proceeds in three steps. Step one establishes the counterfactual. MLS was growing before Messi arrived. Season ticket sales and attendance were already rising, the Apple agreement was already signed, and expansion was already underway. Any honest account must subtract this baseline growth before attributing the remainder to the player. Step two examines each channel separately, identifying the size and the timing of the response. Timing is the key identification tool. Effects that appear within days of the announcement, before any football has been played, cannot be explained by improved sporting performance. Step three tests for spillover by comparing outcomes at Inter Miami with outcomes at clubs that hosted the team and with clubs that did not. 4.4 Why not a formal econometric model This paper does not estimate a new econometric model. Two reasons. First, the necessary transaction level data on ticketing and streaming are proprietary, and the published studies that do have access to them are cited rather than duplicated. Second, the argument concerns a structural and institutional shift, and the appropriate evidence for such a claim is convergent rather than singular. Where causal estimates exist, this paper reports them. Where they do not, it says so. 5. The Case: Anatomy of a Transfer 5.1 The club before Inter Miami CF began play in 2020 under an ownership group that included Jorge Mas and David Beckham. Beckham's own participation traced back to an option in his 2007 Galaxy contract allowing him to buy an expansion franchise at a fixed price, an arrangement that became one of the most profitable clauses in the history of American sport. By mid 2023, the club's sporting position was poor. It sat last in the Eastern Conference. Its home was a temporary venue in Fort Lauderdale with limited capacity. Industry estimates placed its value at roughly 585 million dollars, above the league's lower tier but nowhere near the top. Revenue in 2022, the last full season before the transfer, was around 56 million dollars. 5.2 The deal architecture The transfer that followed was not a conventional contract, and its structure is central to the economic argument of this paper. Reporting indicates that the package combined a substantial base compensation from the club with two elements that had no real precedent in American team sport: a share of revenue arising from the league's commercial partners, reportedly including the apparel supplier and the streaming partner, and an option to acquire an #equity_stake in the club after his playing career. Each element is analytically significant. Revenue sharing with the streaming partner converts the player from an employee of a club into a stakeholder in the league's media business. It aligns his incentives with subscriber growth rather than with wins alone, and it explicitly prices his #audience_portability rather than his marginal product. Revenue sharing with the apparel partner does something similar for merchandise. It acknowledges that jersey demand attaches to the name on the back, not the crest on the front. The equity option converts a wage into an ownership claim. It transforms the athlete from a cost line into a co owner of the asset his presence inflates, and it is the clearest single indicator that the parties understood they were not negotiating over labour but over brand capital. Tenorio's reporting makes clear that this architecture was assembled precisely because MLS could not, under its own rules, simply pay a market wage. The salary structure that had protected the league from the financial collapse of its predecessor also made the biggest signing in its history impossible through ordinary means. The workaround was to bring the league's commercial partners into the deal. That is an institutional innovation, and it is worth naming as such. 5.3 The arrival The announcement in June 2023 and the debut in July 2023 produced an immediate response across every channel. The response preceded competitive results. It preceded the Leagues Cup title that followed weeks later. It was, in the strict sense, an expectations shock: markets, fans and partners repriced the asset on the basis of information alone. 6. Findings 6.1 Franchise valuation The valuation record is the headline finding and the one that most directly supports the #paradigm_shift claim. Before the transfer, Inter Miami was valued at roughly 585 million dollars. By the 2026 valuation cycle, Sportico placed the club at 1.45 billion dollars, the highest in Major League Soccer, representing a rise of more than one hundred and forty percent and a league leading annual growth rate of twenty two percent. Forbes, using a somewhat different methodology, placed the club at 1.35 billion dollars in the same period, also ranking it first in the league and displacing LAFC from the top position it had held in previous years. The two estimates differ in level but agree in direction and in ranking. That agreement matters. Valuation methodologies are proprietary and contestable, but when two independent estimators using different models both move a club from mid table to first place within three years, the underlying signal is unlikely to be noise. Context sharpens the point. In the same 2026 cycle, the average MLS club was valued at roughly 767 million dollars by Sportico and roughly 731 million by Forbes, with total league value near 23 billion dollars across thirty clubs. Five clubs crossed the billion dollar threshold. Inter Miami was worth roughly 3.4 times the least valuable club in the league, a ratio wider than the equivalent gap in the National Basketball Association or the National Football League, and roughly double the ratio that prevailed in MLS five years earlier. This is the first key finding, and it is double edged. The #billion_dollar_boot is real. It is also concentrating. 6.2 Revenue Valuation is a claim about the future. Revenue is a record of the present, and it moved almost as sharply. Inter Miami's revenue was approximately 56 million dollars in 2022. Forbes estimated 180 million dollars in 2024, with roughly 50 million dollars of operating income, and approximately 200 million dollars in 2025, comfortably the highest in the league. Sportico projected revenue approaching 250 million dollars in 2026, which would represent a further increase of roughly seventy five percent from the prior estimate and would leave the club as the league's clear commercial leader. A club roughly quadrupling revenue in three years is not a normal outcome in a mature salary capped league. Nothing in the club's sporting infrastructure changed at a pace that could explain it. The stadium did not open until 2026. The academy did not suddenly produce a generation. What changed was the identity of the man wearing the number 10 shirt. It is worth being precise about the accounting logic here, because it explains why the effect compounds. Under a salary structure that limits what most players can be paid, the incremental revenue attached to a single unusual signing does not get competed away in wages across the roster. It flows disproportionately to the ownership group, and from there into valuation. The rule designed to restrain spending therefore amplified the financial return to the one signing that escaped it. 6.3 Ticketing and the price of presence The ticketing evidence provides the most rigorous causal estimates available, because secondary market prices are recorded at transaction level and can be observed before and after a discrete event. The 2025 study published in the Journal of Sport Management examined precisely this. Its findings are extraordinary in magnitude. Messi's arrival was associated with an increase in Inter Miami home game secondary market ticket prices in the range of approximately 1,113 to 1,237 percent in 2023. Away game ticket prices for matches involving Inter Miami rose by approximately 410 to 477 percent. Two observations follow. First, the home effect is roughly two and a half times the away effect. This is what the #platform_model predicts. The home club sells not only the match but the experience, the hospitality, the merchandise and the association. The away club sells one afternoon. Second, and more importantly for league level claims, the same study found that the spillover to matches not involving Inter Miami was inconsistent. Many clubs experienced insignificant or even negative changes in their home ticket prices after Messi's arrival. This is a finding that deserves far more attention than it has received. It suggests the possibility of an #attention_substitution effect: consumer interest in the league did not simply expand, it partly redistributed toward the matches Messi played in. The aggregate attendance data are consistent with a genuine but moderate league wide gain. MLS reported total attendance of 11.45 million in 2024, an increase of about five percent on the previous year and about fourteen percent on 2022, with an average of 23,234 per match, a record 213 sellouts, and ten clubs setting attendance records. Non Miami matches rose by roughly four percent in 2024. The single most cited data point, a crowd of 72,610 at Arrowhead Stadium when Sporting Kansas City relocated its fixture against Inter Miami, illustrates the #gate_channel in its purest form: a club with a normal capacity of around 18,000 moved to a football stadium and filled it, capturing a windfall it did not have to pay for. That is a textbook #superstar_externality. The honest summary is this. Where Messi appeared, demand exploded. Where he did not, demand grew at approximately the rate it had been growing already. 6.4 Merchandise The merchandise response was immediate and global. Reporting indicates that the Messi jersey became the best selling shirt of the MLS season within forty five minutes of its launch and the best selling shirt in the history of the league's online store within three days. His pink number 10 shirt subsequently became, by multiple accounts, the best selling jersey in world football, and Inter Miami's jersey sales rose to the top of global sports merchandise rankings. Two features of this channel are theoretically important. It is borderless. Merchandise revenue does not require a spectator to attend, to subscribe or even to watch. It monetises affiliation directly, and affiliation, in this case, attached to a person rather than to a city. It is transferable. The purchaser of a Messi shirt in 2023 was, in most cases, not a convert to Inter Miami. He or she was already a Messi supporter, previously buying a different shirt in a different league. From the perspective of global football, a substantial share of this revenue was not created; it was #relocated, moving from Barcelona and Paris to Miami. From the perspective of American soccer, however, relocation is indistinguishable from creation, because the money arrived in a market that had never seen it before. This asymmetry is one reason the #Messi_Effect looks larger from inside the United States than from outside it. 6.5 Media and streaming The media channel is where the structural, as opposed to cosmetic, consequences of the transfer are clearest. Major League Soccer had signed a ten year global agreement with Apple beginning in 2023, reported at an average of roughly 250 million dollars per year, making every match available worldwide without blackouts. The arrangement was bold and, initially, uncertain. Streaming a mid tier league behind a paywall is a risky proposition without a reason for casual viewers to subscribe. Messi supplied the reason. The analytics firm Antenna recorded approximately 110,000 sign ups to MLS Season Pass on the day of his debut, an increase of roughly 280 percent over the number generated on the opening day of the 2023 season. Nearly half of all cumulative sign ups to the service in that period occurred in July 2023, the month of his arrival, inverting the normal pattern in which subscription services acquire most users at the start of a season. Reporting subsequently indicated that the league more than doubled its subscriber base on the platform after his transfer. This is the clearest single demonstration of #audience_portability in the entire case. Consumers who had no relationship with Major League Soccer, in many cases no relationship with American sport at all, purchased a subscription to a domestic American league because a specific individual joined it. The product they were buying was not MLS. It was Messi, and MLS was the delivery mechanism. The channel nonetheless illustrates the #conversion_problem with uncomfortable clarity. Despite the subscriber surge, regular season matches behind the paywall averaged roughly 120,000 unique viewers in 2025, an increase of about fifty percent on 2024 but still a small figure by the standards of major American sports television. Total weekly viewership rose by about 29 percent, though this figure incorporated expanded international linear deals and the inclusion of playoff matches in a free tier. The economics of the deal also proved difficult at club level: teams were responsible for production costs and reportedly netted around 5 million dollars each, against roughly 40 million per club in the National Hockey League following its most recent broadcast agreement. In November 2025 the agreement was restructured, with the end date moved earlier, to 2029, and consumer pricing reduced in an effort to widen the audience. The interpretation is important and it cuts against the triumphalist reading. Messi delivered subscribers. He did not, by himself, deliver habitual viewers. Acquisition and retention are different problems, and only the first can be solved by signing a player. 6.6 Sponsorship Sponsorship is the channel where the effect is most likely to be durable, because sponsorship contracts are multi year and because they price attention prospectively. League sponsorship revenue rose by approximately thirteen percent in 2024 to around 665 million dollars, according to research firm SponsorUnited. At club level, Inter Miami's commercial portfolio expanded rapidly, and the club's global visibility made it a viable partner for multinational brands that would not previously have considered an MLS property. The mechanism is straightforward. A sponsor buys impressions and association. Messi delivered both at a volume that no other asset in the league could match, and he delivered them to precisely the international and Spanish speaking audiences that American brands had struggled to reach through domestic sport. The value created here is partly independent of match results, which is why it is more resilient than gate revenue. 6.7 Sporting outcomes It would be a mistake to treat the case as purely commercial. Messi also produced on the field, which matters because it sustained the attention. Inter Miami won the Leagues Cup in 2023, weeks after his arrival, the first trophy in the club's history. It won the Supporters' Shield in 2024, when Messi was named the league's Most Valuable Player, and set a regular season points record. In 2025 he won the league's Golden Boot with 29 regular season goals, and the club won the MLS Cup, its first league championship. Across competitions his output for the club has been substantial by any standard, let alone for a player in his late thirties. This matters analytically for one reason. Had Messi arrived and failed, the attention decay would have been rapid, and the commercial effects documented above would have proved fragile. Sporting success did not create the financial effect, which appeared before any match was played, but it sustained it. Performance is not the source of the value in this model. It is the maintenance cost of the value. 6.8 The uneven geography of the effect Pulling the channels together produces a picture that is more complicated than the popular account. At Inter Miami, every channel moved sharply and in the same direction. Valuation, revenue, ticketing, merchandise and sponsorship all repriced upward, and the club moved from the middle of the league to the top of it. At clubs hosting Inter Miami, the gate channel delivered a genuine windfall, sometimes an enormous one, but the windfall was episodic. A club gets one Messi fixture per season. At clubs not hosting Inter Miami, the effect was weak, and in secondary ticket markets it was sometimes negative. The peer reviewed evidence on this point is unambiguous, and it should temper the claim that the whole league was lifted. At league level, the media and sponsorship channels did produce structural gains: more subscribers, higher sponsorship revenue, greater global visibility, and a stronger negotiating position ahead of the 2026 World Cup on North American soil. The resulting pattern is one of concentrated gains with diffuse spillovers. The gap between the most and least valuable clubs widened. Six of the seven least valuable clubs recorded valuation growth of two percent or less in a year when Inter Miami grew by double digits. A league whose entire founding philosophy was built on parity has, as a direct consequence of its greatest commercial success, become measurably less equal. 7. Discussion 7.1 Is this really a paradigm shift? The word #paradigm_shift is overused in sports business writing, and it deserves scrutiny. The case for it here rests on three claims, and I think two of them survive. The first claim is that the unit of value changed. Traditionally the club is the asset and the player is an input. In this case the player was the asset and the club was, for a period, an input into his commercial operation. The evidence for this is the deal structure itself: revenue sharing with league commercial partners and an equity option are not the terms one offers to an employee. They are the terms one offers to a joint venture partner. This claim holds. The second claim is that #brand_equity became transferable across leagues without meaningful decay. The evidence supports this. Merchandise, streaming subscriptions and sponsorship all moved with the player rather than remaining with his former employers, and the scholarly work on Saudi transfers finds a similar pattern of brand resilience. Twenty years ago this was not obviously true. An athlete's commercial value was closely tied to the prestige of his competition. It no longer is, because the athlete now owns the direct channel to his audience. This claim also holds. The third claim, the strongest version of the thesis, is that a single athlete rewrote the financial trajectory of an entire league. This claim needs qualification. He rewrote the trajectory of one club decisively. He raised the ceiling of the league's commercial ambitions. He supplied the streaming partner with a reason to believe in the product. But league level attendance grew at roughly the rate it had been growing before, per match viewership remained modest, per club media income remained low, and the peer reviewed ticket price evidence shows that spillover to matches without him was weak. The honest verdict is that Messi shifted the ceiling without lifting the floor. That is still a paradigm shift, but it is a shift in what is possible, not a shift in what has already happened. 7.2 The competitive balance problem Every league that pursues a superstar strategy encounters the same tension, and MLS is now living inside it. The #salary_budget system exists to preserve competitive balance and financial discipline. It was designed after the collapse of the North American Soccer League, a league that spent itself into extinction chasing exactly this kind of stardom in the 1970s. The Designated Player rule was the first crack in that system, opened for Beckham. The Messi arrangement widened the crack considerably, because it required the league's commercial partners to participate in compensating a single player. The consequence is now visible in the valuation table. The distance between the top and the bottom of MLS is larger than in the NBA or the NFL, and it is growing. Clubs at the bottom cannot generate the revenue to compete, cannot attract the investment to grow, and in some cases have struggled to find buyers at all. Tenorio's reporting captures the resulting boardroom argument with unusual clarity. Jorge Mas, the Inter Miami owner, argued that the league's restrictive spending rules were holding down the quality of the product and that the structure should be rebuilt from the foundations. Others resisted. The league considered significant changes to roster rules and elected to defer them until after the 2026 World Cup. Whether that was prudence or paralysis is a judgment the reader can make. What is not in dispute is that the moment of maximum leverage, the period when the world's most famous footballer was actively playing in the league, was allowed to pass without the structural changes that the club's owner believed were necessary. This is the #conversion_problem in institutional form. 7.3 The comparison case: Ronaldo and the Saudi Pro League The Ronaldo transfer to Al Nassr in December 2022 offers a useful comparison, and the peer reviewed evidence is better. Schreyer and Singleton's 2025 study found that Ronaldo raised home attendance by roughly twenty percent, away attendance by roughly fifteen percent, and attendance at matches he did not play in by roughly three percent. Mutz's 2024 study found a measurable rise in global attention to the Saudi league following the wave of signings. The parallels are strong: an aging superstar, a league seeking legitimacy, a rapid commercial response, and a concentration of value in a small number of clubs. The differences are instructive. The Saudi strategy was state directed and pursued through sustained multi club investment, meaning that Ronaldo was the first of many. The American strategy was market directed and remained, in practice, a single asset strategy. MLS acquired one superstar and hoped the effect would generalise. The evidence from both cases suggests that it does not generalise on its own. 7.4 What happens next: the succession problem Messi re signed with Inter Miami into the late 2020s, and the club opened Miami Freedom Park, a 25,000 seat stadium and the first phase of a large mixed use development, in April 2026. The 2026 World Cup, hosted across North America, arrived at the ideal moment to consolidate interest. Nonetheless, the #post_Messi_question is unavoidable, and the framework in Section 3 gives it structure. When he departs, the gate channel will fall quickly. The merchandise channel will fall sharply. Whether the media and sponsorship channels hold depends entirely on what was built while he was present. The assets that will remain are identifiable: a permanent stadium and its associated real estate, a restructured media agreement, an elevated sponsorship base, a larger and more international fan base, a stronger position in Spanish speaking markets, and a body of evidence that global stars can succeed commercially in the United States. The assets that will not remain are the ones that depend on his physical presence. The verdict on the #Messi_Effect will therefore not be written by the valuation tables of 2026. It will be written by the valuation tables of 2032. 7.5 Implications for theory Three theoretical implications follow. The star effects literature should extend its dependent variables. Attendance and ticket prices capture the #gate_channel well, and capture the media, merchandise and valuation channels not at all. In an era where the largest financial responses occur in streaming subscriptions and franchise values, this is a serious limitation. The superstar externality should be treated as heterogeneous rather than uniform. The MLS evidence shows a large effect on the star's own club, a substantial but episodic effect on hosts, and a weak or absent effect elsewhere. Aggregating these into a single league level coefficient conceals more than it reveals, and may explain some of the inconsistency in the empirical literature. Sports economics should incorporate the athlete as a platform owner. The Messi contract, with its revenue sharing and equity option, is not a wage contract. It is a partnership agreement, and it will not be the last of its kind. As athletes accumulate direct audience relationships, the bargaining boundary between labour and capital in sport will continue to move. 8. Limitations Several limitations must be acknowledged, and they are not trivial. The valuation and revenue figures used here are industry estimates rather than audited financial statements. Sportico and Forbes disagree on the level of Inter Miami's value by roughly one hundred million dollars, which indicates the range of uncertainty involved. These estimates are the best available, but they are estimates. The attribution problem is real. MLS was growing before Messi arrived. Season ticket sales, attendance, expansion and the Apple agreement all preceded him. Separating his contribution from an existing trend, and from the effect of the 2026 World Cup, is genuinely difficult, and this paper does not claim to have solved it. The timing evidence, particularly the streaming spike on the day of his debut and the ticket price response before he had played, provides reasonable grounds for attribution, but it is not a randomised experiment. The study relies on a single peer reviewed causal estimate of the ticketing effect and a single peer reviewed estimate of the comparable Ronaldo effect. Replication is thin because the events are recent. The case is ongoing. Messi remains under contract, the new stadium is barely open, the World Cup has only just been played, and the media agreement has been restructured but not yet expired. Any conclusion drawn now is provisional. Finally, the paper draws on journalistic sources, including Tenorio's book, for the internal narrative of the deal and of the league's governance debates. Such sources are valuable and, in this instance, unusually well documented, but they are not peer reviewed and they reflect the access and the perspective of their author. 9. Conclusion Lionel Messi joined a club that was last in its conference and left it as the most valuable franchise in Major League Soccer. Along the way, the club's revenue roughly quadrupled, its jersey became the best selling shirt in world football, ticket prices for its home matches rose by more than a thousand percent on the secondary market, and the league's streaming partner recorded more subscriber sign ups on the day of his debut than on the opening day of its season. These are not the numbers of a very good player joining a team. They are the numbers of a #media_property being installed inside an industry. This paper has argued that the #Messi_Effect represents a genuine change in how value is created and captured in professional sport. The athlete's audience has become #portable. His #brand_equity survives a move down the competitive hierarchy. His compensation increasingly resembles a partnership stake rather than a wage. And a league's commercial partners, rather than its clubs, can now be brought into the financing of a single signing. Each of these things was difficult or impossible a generation ago. Together, they justify the language of #paradigm_shift. But the paper has also insisted on the limits of the phenomenon, and those limits are where the real lessons lie. The gains were concentrated. The clubs that hosted him prospered for an afternoon. The clubs that did not host him grew at the rate they were already growing, and in some secondary markets they did not grow at all. The gap between the richest and poorest clubs in a league founded on the principle of parity is now wider than in the NBA or the NFL. Per club media income remains low. Per match viewership, while rising, remains modest. And the league, presented with the largest commercial opportunity in its history, chose to defer the structural reforms that its most successful owner argued were necessary to convert that opportunity into permanent competitive strength. The #billion_dollar_boot, in other words, was real. Whether it was a foundation or a firework is a question that only time and the league's own choices will answer. A superstar can move a valuation in a season. Only an institution can hold it. For students of sports economics, the case yields a lesson that generalises well beyond football. In an economy where attention is the scarcest input and where individuals increasingly own their own distribution, the traditional boundary between the asset and the employee has become unstable. Messi did not merely play for Inter Miami. For a period of years, in the most literal economic sense available, Inter Miami played for Messi. 10. Practical Implications and Future Research 10.1 For league administrators Treat the arrival of a global star as a time limited window rather than a permanent condition. The relevant question during the window is not how much revenue is being generated but how much of it is being converted into stadiums, long term sponsorship agreements, media catalogue and youth infrastructure that survive the player's departure. Anticipate inequality. Superstar strategies concentrate value by design. If a league values parity, it must build redistribution mechanisms before the star arrives, not after the valuation gap has opened. 10.2 For club executives Recognise that a #human_brand of this magnitude cannot be acquired within conventional wage structures, and that acquiring one may require partnership arrangements with commercial and media stakeholders. Recognise also that such arrangements transfer part of the upside to the player, permanently. 10.3 For researchers Four lines of inquiry follow directly from this case. First, post departure decay: measure the rate at which each channel declines after a superstar leaves, using the Beckham period as a historical benchmark and the eventual Messi departure as the test. Second, #attention_substitution: test rigorously whether interest in a league expands or merely redistributes toward the star's fixtures. The 2025 ticket price evidence suggests the latter is a real possibility and it has significant policy implications. Third, subscriber retention: track the cohort of streaming subscribers acquired around a star's debut and measure how many remain two, three and five years later. This is the single most valuable unanswered empirical question in the case. Fourth, contract architecture: examine the spread of equity and revenue sharing arrangements for elite athletes across leagues, and the implications for labour relations and for the valuation of clubs. References Anderski, M., Griebel, L., Stegmann, P., and Strobel, T. (2023). Empowerment of human brands: Brand meaning co-creation on digital engagement platforms. Journal of Business Research, 166, 113905. Birnbaum, J. (2025). The most valuable MLS teams 2025. Forbes. Birnbaum, J. (2026). The most valuable MLS teams 2026. Forbes. Jedelhauser, F., Flepp, R., and Franck, E. (2023). Overshadowed by popularity: The value of second-tier stars in European football. Journal of Sports Economics, 24(8), 1026-1054. Mutz, M. (2024). A new flagship of global football: The rise of global attention towards Saudi Arabia's pro league. Frontiers in Sports and Active Living, 6, 1293751. Noh, Y., Ahn, N. Y., and Anderson, A. J. (2023). Do consumers care about human brands? A case study of using Zaltman Metaphor Elicitation Technique to map two athletes' engagements in social and political advocacy. European Sport Management Quarterly, 23(6), 1732-1758. Reilly, P., Solow, J., and von Allmen, P. (2023). When the stars are out: The impact of missed games on NBA television audiences. Journal of Sports Economics, 24(7), 877-902. Rewilak, J. (2023). The designated player policy rule and attendance demand in Major League Soccer. Journal of Sports Economics, 24(4), 475-496. Scarfe, R., Singleton, C., and Telemo, P. (2021). Extreme wages, performance, and superstars in a market for footballers. Industrial Relations: A Journal of Economy and Society, 60(1). Schreyer, D., and Ansari, P. (2022). Stadium attendance demand research: A scoping review. Journal of Sports Economics, 23(6), 749-788. Schreyer, D., and Singleton, C. (2025). Cristiano of Arabia: Did Ronaldo increase Saudi Pro League attendances? Contemporary Economic Policy, 43(2), 260-270. Stephenson, E. F. (2024). International competitions, star players, and NWSL attendance. Journal of Sports Economics. Tenorio, P. (2026). The Messi Effect: How the Global Legend Changed the Future of American Soccer. New York: St. Martin's Press. The star effect of Lionel Messi on secondary market ticket prices in Major League Soccer. (2025). Journal of Sport Management, 40(3). Antenna. (2023). The Messi effect: MLS Season Pass sign-up analysis. Antenna Insights Report. Sportico. (2026). MLS team valuations 2026. Sportico Valuations Report. ESPN. (2024). Messi-mania helps drive record attendance and growth for MLS. ESPN. SponsorUnited. (2025). Sports marketing and sponsorship report: Major League Soccer. #Lionel_Messi #Inter_Miami #Major_League_Soccer #Sports_Economics #Superstar_Effect #Franchise_Valuation #Brand_Equity #Sports_Finance #American_Soccer #Streaming_Rights #Sports_Marketing #Competitive_Balance #Athlete_Branding #Global_Football_Business

The #Cartagena_Protocol on Biosafety, adopted on 29 January 2000 and in force since 11 September 2003, is the first legally binding international agreement devoted specifically to #biosafety. It supplements the Convention on Biological Diversity and aims to ensure an adequate level of protection in the safe transfer, handling and use of #living_modified_organisms produced by #modern_biotechnology that may have adverse effects on the conservation and sustainable use of #biological_diversity, taking also into account risks to human health, with a specific focus on movements across national borders. This article reviews the origins, legal architecture, operational machinery and practical performance of the Protocol, and evaluates whether an instrument designed in the 1990s can still govern the biotechnologies of the 2020s. The study uses a doctrinal and analytical literature review method, combining the text of the treaty and the decisions of its governing body with recent peer reviewed scholarship published mainly between 2021 and 2026. Three findings emerge. First, the Protocol succeeded in institutionalising #precaution, #advance_informed_agreement and risk_assessment as global norms, and it created a durable information infrastructure through the Biosafety_Clearing_House. Second, implementation remains highly uneven: many parties, especially in low income and middle income countries, still lack the technical, financial and administrative capacity to operate the system they have legally accepted, and the largest exporter of living modified crops is not a party. Third, and most seriously, the Protocol is drifting out of step with the science it governs. #Genome_editing, #gene_drives, #synthetic_biology and #digital_sequence_information raise definitional and procedural questions that recent meetings of the parties have answered with voluntary, imprecise or postponed instruments rather than binding rules. The article argues that this softening of rule development, described in recent scholarship as a de-legalisation trend, is the central risk to the future relevance of the Protocol. It concludes with a set of reform pathways, including clarification of the definition of a living modified organism, modernisation of Annex III, investment in detection capacity, and a more honest integration of #socio_economic_considerations into decision making. The article is written for students of environmental law, international relations, biotechnology policy and the life sciences. Keywords: biosafety; Cartagena Protocol; living modified organisms; precautionary approach; risk assessment; biodiversity; genome editing; gene drives; international environmental law; biotechnology governance 1. Introduction Few technologies have divided governments, scientists, farmers and consumers as sharply as the genetic modification of living things. Within a few years of the first commercial planting of transgenic crops in the mid 1990s, the world faced a governance problem that no existing treaty was designed to solve. Seeds, fish, micro organisms and insects carrying novel genetic combinations could be shipped across borders in the same way as any other commodity, but unlike a barrel of oil or a bale of cotton they could reproduce, spread, and interact with wild relatives once they arrived. A living thing that escapes cannot be recalled. The #Cartagena_Protocol on Biosafety was the international response to that problem. It was adopted in Montreal on 29 January 2000, after four years of difficult negotiations, and it entered into force on 11 September 2003 once fifty states had ratified it. It is a supplementary agreement, or protocol, to the #Convention_on_Biological_Diversity, the framework treaty agreed at the Rio Earth Summit in 1992. Today it has been joined by more than 170 parties, which makes it one of the most widely accepted environmental agreements in existence, even though several major agricultural exporters, including the United States, have never become parties. The core promise of the Protocol is simple to state. A country should not have to accept the import of a living organism carrying a novel genetic combination without first being told what it is, being given the chance to assess the risks it may pose to its own ecosystems, and being allowed to say no, or to say yes with conditions. That promise translates into a legal machinery of notification, consent, risk assessment, documentation and information exchange that this article describes in detail. Yet a treaty is not only a text. It is also a practice, a set of institutions, and a political settlement that reflects the science and the power relations of the moment when it was written. The science has moved. In 2000, the paradigm case of a #living_modified_organism was a maize plant carrying a bacterial gene inserted more or less at random by a gene gun or by an agrobacterium vector. In the 2020s, the frontier is precise editing with CRISPR associated proteins that may leave no foreign DNA at all, engineered #gene_drives designed to spread deliberately through wild populations, self spreading vaccines for wildlife, organisms designed on a computer from #digital_sequence_information, and the growing convergence of biological design with artificial intelligence. Whether the Protocol still covers these things, and whether its procedures are fit to assess them, is now the central question of global #biotechnology_governance. This article has five aims. The first is to explain, in plain language, what the Protocol actually says and how its procedures work, because a great deal of public debate about it proceeds without that basic understanding. The second is to trace the negotiating history and show why the text reads as it does, since almost every ambiguity in the treaty is the fossil of a political compromise. The third is to assess implementation: what has worked, what has not, and why performance differs so much between regions. The fourth is to examine the pressure that new biotechnologies place on the definitions and procedures of the Protocol, drawing on recent scholarship. The fifth is to set out concrete reform options. The argument advanced here is that the Cartagena Protocol has been a considerable normative success and a partial operational one. It made #precaution a workable legal concept rather than a slogan, it gave importing states a right to information and a right to decide, and it built the first global public database on the regulation of #modern_biotechnology. But its capacity to keep pace with science has weakened rather than strengthened over the past decade. Recent decisions of the governing bodies have tended towards voluntary guidance, vague wording and postponed decisions rather than binding rules, a pattern that Tsioumani and Rabitz (2026) analyse as the de-legalisation of biotechnology governance under the Convention. If that trend continues, the Protocol risks becoming a monument rather than an instrument. 2. Method and Scope This is a review article. It does not report new laboratory data or new field measurements. Its method is doctrinal and analytical, which is the standard approach in legal and policy scholarship, combined with a structured review of recent scientific and social scientific literature. Three categories of material were used. The first is primary legal material: the text of the Convention on Biological Diversity, the text of the Cartagena Protocol and its annexes, the text of the Nagoya Kuala Lumpur Supplementary Protocol on Liability and Redress, and the decisions adopted by the Conference of the Parties serving as the Meeting of the Parties to the Protocol, known as the #COP_MOP. The second is secondary scholarly literature. Priority was given to peer reviewed articles and academic book chapters published between 2021 and 2026, in order to capture the most recent state of debate about #genome_editing, #gene_drives, #synthetic_biology and #digital_sequence_information. Older sources are referred to in the text only where they are of historical importance. The third category is comparative national and regional material, drawn from published studies of #national_biosafety_frameworks in Africa, Asia, Latin America and Europe. The analysis proceeds in four movements. Sections 3 to 5 are descriptive and explain the origin, objective, scope and operational core of the Protocol. Sections 6 to 10 are analytical and examine the instruments that give the Protocol its distinctive character: risk_assessment, the #precautionary_approach, information exchange, capacity_building, #public_participation, compliance and #liability_and_redress. Sections 11 to 13 are evaluative and consider the relationship with trade law, the record of implementation, and the challenge of new biotechnologies. Sections 14 and 15 draw the assessment together and propose reforms. Two limitations should be stated openly. First, the literature on biosafety is polarised. Authors writing from an agricultural innovation perspective tend to regard the Protocol as an obstacle to beneficial technology, while authors writing from an ecological or civil society perspective tend to regard it as too weak. This article attempts to present both positions fairly and to distinguish between empirical claims and normative preferences. Second, national implementation is a moving target; regulations described here as current may change, and readers should verify the position in any specific jurisdiction before relying on it. 3. Origins: From Rio to Cartagena 3.1 The seed in the Convention on Biological Diversity The Cartagena Protocol did not appear from nowhere. It grew out of two provisions of the 1992 Convention on Biological Diversity. Article 8(g) requires every party to establish or maintain the means to regulate, manage or control the risks associated with the use and release of #living_modified_organisms resulting from biotechnology which are likely to have adverse environmental impacts that could affect the conservation and sustainable use of biological diversity, taking also into account risks to human health. Article 19(3) went further and asked the parties to consider the need for, and the modalities of, a protocol setting out appropriate procedures in the field of the safe transfer, handling and use of any living modified organism that may have an adverse effect on biological diversity. These two provisions embody the twin attitude that the Convention takes towards biotechnology. On one hand, biotechnology is treated as a promise: the Convention encourages access to and transfer of technologies, including biotechnology, that are relevant to conservation and sustainable use. On the other hand, it is treated as a risk that must be managed. That double character, promise and risk, runs through the whole biosafety debate and explains why compromise texts are so often ambiguous. As Tsioumani and Rabitz (2026) note, the Convention emerged in the 1990s as the central international forum for managing the complex interface between biotechnology and biodiversity, and questions of ownership, safety and benefit sharing were at the heart of the negotiations from the beginning. 3.2 The negotiation, 1996 to 2000 An open ended working group, usually called the Biosafety Working Group, was established in 1995 and met six times between 1996 and 1999. Negotiations were among the most acrimonious in the history of multilateral environmental diplomacy. They failed spectacularly at the meeting in Cartagena, Colombia, in February 1999, which is why the Protocol carries the name of a city where it was not actually adopted. Agreement was finally reached at a resumed session in Montreal in January 2000. The negotiation was structured around blocs rather than around the usual developed and developing country split. The so called Miami Group, made up of major exporters of agricultural commodities, argued for a narrow instrument that would not disrupt commodity #trade and that would rest on sound science. The European Union and its allies argued for a broad, precautionary instrument covering a wide range of organisms and uses. A group of developing countries, often called the Like Minded Group, argued for strong rights for importing states, including the right to take into account #socio_economic_considerations, and for provisions on #liability_and_redress and #capacity_building. Smaller blocs represented compromise positions and the interests of central and eastern Europe. The final text is a settlement between these positions rather than a coherent scheme drafted by one hand. It contains the strong consent procedure that importers wanted, but with an exemption for the most commercially significant category of shipments, namely commodities intended for food, feed or processing. It contains a #precautionary_approach, but it also contains language on scientific evidence and on the need for decisions to be based on #risk_assessment. It contains a savings clause on the relationship with other international agreements that manages to say, in effect, that the Protocol neither is nor is not subordinate to the rules of the World Trade Organization. Almost every controversy that has arisen since 2003 can be traced back to one of these compromises. 3.3 Entry into force and institutional growth The Protocol entered into force on 11 September 2003, ninety days after the fiftieth instrument of ratification. Its governing body is the Conference of the Parties to the Convention serving as the Meeting of the Parties to the Protocol. This body has met regularly since 2004 and has generated a substantial body of decisions on #risk_assessment, #risk_management, #compliance, #capacity_building, public awareness, socio economic considerations, and the operation of the #Biosafety_Clearing_House. A supplementary treaty on liability, the Nagoya Kuala Lumpur Supplementary Protocol, was adopted in 2010 and entered into force in 2018. The institutional architecture, then, is not a single document but a living regime: a framework convention, a protocol, a supplementary protocol, a compliance committee, an information clearing house, a series of expert groups, and a stream of decisions that interpret and extend the original text. Understanding the Protocol means understanding this regime as a whole. 4. Objective, Scope and the Problem of Definitions 4.1 The objective Article 1 states the objective. In line with the precautionary approach contained in Principle 15 of the Rio Declaration on Environment and Development, the Protocol seeks to contribute to ensuring an adequate level of protection in the field of the safe transfer, handling and use of living modified organisms resulting from modern biotechnology that may have adverse effects on the conservation and sustainable use of biological diversity, taking also into account risks to human health, and specifically focusing on transboundary movements. Several features of this sentence deserve attention, because students often misread them. First, the standard is an adequate level of protection, not the elimination of risk. The Protocol is a risk management instrument, not a prohibition. Second, human health is included, but in a subordinate way. The phrase taking also into account risks to human health means that health risks are relevant to decisions taken under the Protocol, but the Protocol is not a food safety treaty. Food safety is dealt with elsewhere, principally through the Codex Alimentarius system. Third, the specific focus is on #transboundary_movement. The Protocol is fundamentally about what crosses borders. Purely domestic activities are largely left to national law, although Article 2(4) preserves the right of parties to take action that is more protective, provided it is consistent with the objective and with other international obligations. 4.2 Scope and exclusions Article 4 sets out the scope: the Protocol applies to the transboundary movement, transit, handling and use of all living modified organisms that may have adverse effects on the conservation and sustainable use of biological diversity, taking also into account risks to human health. Two carve outs matter. Article 5 excludes living modified organisms that are pharmaceuticals for humans and that are addressed by other relevant international agreements or organisations. Article 6 provides that living modified organisms in transit, and those destined for #contained_use in the party of import, are not subject to the advance informed agreement procedure, although parties retain the right to regulate transit and to set standards for contained use. The most consequential distinction, however, is between living modified organisms intended for intentional introduction into the environment, such as seeds for planting, and living modified organisms intended for direct use as food or feed, or for processing. The second category, usually abbreviated as LMO FFP, includes the bulk shipments of grain that dominate world agricultural trade. These shipments are handled under a lighter procedure in Article 11 rather than under the full consent procedure. This was the price of agreement with the exporting states, and it remains the largest hole in the Protocol from the perspective of importing states. 4.3 What counts as a living modified organism Article 3 provides the definitions on which everything else depends. A living organism is any biological entity capable of transferring or replicating genetic material, including sterile organisms, viruses and viroids. This is deliberately broad. It includes things that biologists would hesitate to call alive. A living modified organism is any living organism that possesses a novel combination of genetic material obtained through the use of #modern_biotechnology. Modern biotechnology means the application of in vitro nucleic acid techniques, including recombinant DNA and the direct injection of nucleic acid into cells or organelles, or the fusion of cells beyond the taxonomic family, that overcome natural physiological reproductive or recombination barriers and that are not techniques used in traditional breeding and selection. Three points follow. First, the definition is process based, not product based. What matters is how the organism was made, not what it is. Second, the definition is technique specific: it names in vitro nucleic acid techniques and cell fusion beyond the taxonomic family. Third, it contains a functional test: the technique must overcome natural barriers and must not be a traditional breeding technique. In practice, the term living modified organism is used interchangeably with the term genetically modified organism, and many national laws use the latter. The equivalence is convenient but not perfect, and, as later sections show, the imperfection has become a serious governance problem in the age of #genome_editing (Vengadesen et al., 2025). 5. The Operational Core: Consent, Notification and Documentation 5.1 Advance informed agreement The heart of the Protocol is the #advance_informed_agreement procedure set out in Articles 7 to 10 and Article 12. It applies to the first intentional transboundary movement of a living modified organism intended for intentional introduction into the environment of the party of import. The procedure runs as follows. The exporter, or the exporting party, must notify the competent national authority of the importing party in writing before the shipment takes place. Annex I lists the information that must be supplied: the identity of the organism, the details of the recipient organism and the donor organism, the intended use, the quantity, a previous and existing risk assessment report, and suggested methods for safe handling, storage, transport and use. The importing party must acknowledge receipt within ninety days and must communicate a decision within two hundred and seventy days. The decision may be to approve, to approve with conditions, to prohibit, to request additional information, or to extend the deadline. Crucially, a failure to respond does not imply consent. Silence is not agreement, which reverses the default rule found in many trade instruments and places the burden on the exporter to obtain a positive decision. Article 12 allows an importing party to review and change a decision in the light of new scientific information about potential adverse effects. This is an important expression of adaptive governance: a licence is not a permanent entitlement. 5.2 Commodities for food, feed or processing Article 11 governs living modified organisms intended for direct use as food, feed or processing. Here there is no notification to individual importing countries and no requirement of prior consent. Instead, a party that takes a final domestic decision on the domestic use, including placing on the market, of such an organism must inform the other parties by posting the decision to the #Biosafety_Clearing_House within fifteen days. An importing party may then take its own decision under its domestic regulatory framework. A developing country party or a party with an economy in transition that has no domestic framework may declare, through the Clearing House, that it will take decisions on the basis of a #risk_assessment and within a defined period. The practical effect is a two speed system. Seeds for planting are subject to a strict consent regime. Grain in bulk, which is far larger in volume and economic value, is subject to a notification regime supported by a database. Whether this asymmetry is a sensible allocation of regulatory effort, on the basis that grain intended for crushing is unlikely to be planted, or a serious gap, on the basis that grain spills and grain gets planted, remains contested. 5.3 Handling, transport, packaging and identification Article 18 requires that living modified organisms subject to transboundary movement are handled, packaged and transported under conditions of safety, and that shipments are accompanied by #documentation. The documentation requirements differ by category. For organisms destined for contained use, the documentation must identify them clearly as living modified organisms and specify requirements for safe handling and contact points. For organisms destined for intentional introduction into the environment, the documentation must clearly identify them as living modified organisms, specify their identity and traits, and give handling and contact information. For commodities, the original text required only that documentation state that the shipment may contain living modified organisms not intended for intentional introduction into the environment. The phrase may contain was, for years, the single most criticised phrase in the Protocol, because a document that says a cargo may contain something tells the importing country almost nothing. A later decision of the Meeting of the Parties tightened the position by requiring, where the identity of the organisms is known through means such as identity preservation systems, that the documentation state that the shipment contains them, and by requiring the common names, scientific names and unique identifiers to be given. The improvement was real, but it depends on the exporter knowing what is in the shipment, and bulk commodity systems are designed precisely not to preserve that information. This is where #detection_and_identification capacity becomes decisive. A documentation rule without a laboratory to verify it is an honour system. Many importing states, especially in Africa and in small island developing states, lack accredited laboratories able to detect and quantify events in a mixed cargo, and the arrival of edited organisms that contain no foreign DNA makes the detection problem harder still (Eckerstorfer, Agapito-Tenfen, and Kleter, 2023). 6. Risk Assessment and Risk Management 6.1 Article 15 and Annex III Article 15 provides that decisions under the advance informed agreement procedure must be based on a #risk_assessment carried out in a scientifically sound manner in accordance with Annex III, and that the importing party may require the exporter to carry out and pay for the assessment. #Annex_III sets out the principles and methodology. The assessment must be carried out on a case by case basis. It must be scientifically sound and transparent. Lack of scientific knowledge or scientific consensus is not to be interpreted as indicating a particular level of risk, an absence of risk, or an acceptable risk. Risks are to be considered in the context of the risks posed by the non modified recipients or parental organisms in the likely potential receiving environment. The methodology has five steps. First, identify any novel genotypic and phenotypic characteristics associated with the living modified organism that may have adverse effects. Second, evaluate the likelihood that these adverse effects will be realised, taking into account the level and kind of exposure of the likely potential receiving environment. Third, evaluate the consequences should the adverse effects be realised. Fourth, estimate the overall risk posed by the organism on the basis of the likelihood and the consequences. Fifth, recommend whether the risks are acceptable or manageable, including, where necessary, identification of strategies to manage them. Points to be considered include the taxonomic status and biology of the recipient and donor organisms, the characteristics of the vector, the characteristics of the insert, the identity and function of the modification, detection and identification methods, and information about the likely potential receiving environment. The strength of this design is that it is contextual. The same maize event may be low risk in a country with no wild relatives and materially different in a centre of origin where #gene_flow to landraces and wild relatives is possible. The weakness is that it is demanding. A rigorous, case by case, environment specific assessment requires ecological baseline data, taxonomic expertise, molecular capacity and time. Many parties have none of these in sufficient quantity. 6.2 Risk management and monitoring Article 16 obliges parties to establish and maintain appropriate mechanisms, measures and strategies to regulate, manage and control risks identified in the risk assessment. It requires measures to prevent unintentional transboundary movements, and it requires an observation period appropriate to the life cycle or generation time of the organism before it is put to its intended use. Article 17 obliges a party to notify affected or potentially affected states, the Clearing House and, where appropriate, relevant international organisations, when it knows of an occurrence within its jurisdiction that leads, or may lead, to an unintentional transboundary movement of a living modified organism likely to have significant adverse effects. Emergency consultation is then required. In practice, post release #monitoring is the weakest link in most national systems. Approval decisions are taken, and then very little systematic ecological surveillance follows. This matters especially for organisms designed to persist and spread. 7. The Precautionary Approach 7.1 What the Protocol actually says The #precautionary_approach is the philosophical signature of the Protocol, and it is also the most misunderstood part of it. The approach appears in three places. The preamble reaffirms the precautionary approach contained in Principle 15 of the Rio Declaration. Article 1 states that the objective is to be pursued in accordance with that approach. And Articles 10(6) and 11(8) contain the operative rule: lack of scientific certainty due to insufficient relevant scientific information and knowledge regarding the extent of the potential adverse effects of a living modified organism on the conservation and sustainable use of biological diversity in the party of import, taking also into account risks to human health, shall not prevent that party from taking a decision, as appropriate, with regard to the import of the living modified organism in question, in order to avoid or minimise such potential adverse effects. Three things follow. First, precaution here is permissive, not mandatory. It gives the importing state a legal shield if it decides to restrict an import in the face of uncertainty. It does not oblige any state to ban anything. Second, precaution operates within the risk assessment framework, not instead of it. A party must still have carried out or considered an assessment; the uncertainty that justifies precaution is uncertainty that the assessment itself reveals. Third, this was a novel move in international law, because it applied a precautionary rule to a technology that had not been demonstrated to be harmful. 7.2 The critique of precaution Critics argue that the precautionary approach, particularly as it has been applied in the #European_Union, has become a licence for indefinite delay. Because absence of evidence of harm can always be characterised as scientific uncertainty, a precautionary regulator can always ask for one more study. Vengadesen, Abdul Aziz, and Jones (2025) argue that the interpretation of the precautionary principle has created legal barriers that have delayed the adoption of beneficial technologies, and they propose a principle based approach that sets out high level objectives and allows regulators to adapt as the evidence changes, rather than a rigid process trigger. Caradus (2023), reviewing regulatory processes across more than fifty jurisdictions, argues in a similar direction: regulation is necessary, but the cost of regulation falls disproportionately on small developers and public sector breeders, and the result is that the technology is concentrated in the hands of the few companies that can afford the compliance bill. Defenders reply that precaution is not the enemy of science but a rule about who bears the burden of uncertainty. In their view the alternative, which is to permit release until harm is demonstrated, places the cost of error on the ecosystem and on the importing country, which is exactly the wrong place for an irreversible risk. Ecological harm from a self replicating organism cannot be compensated in the way that a defective product can be recalled. Both positions contain truth, and the honest conclusion is that the argument is not about science at all. It is about how societies distribute the risk of being wrong. Precaution assigns it to the innovator; permissiveness assigns it to the environment and to the importing public. That is a political and ethical choice, and it should be argued as such rather than disguised as a technical dispute. 8. Information, Participation and Capacity 8.1 The Biosafety Clearing House Article 20 establishes the #Biosafety_Clearing_House as part of the clearing house mechanism of the Convention. It is an internet based platform through which parties make available laws, regulations and guidelines, decisions on import, risk assessment summaries, national contact points, bilateral and regional agreements, and reports on implementation. The Clearing House is one of the quiet successes of the regime. Before it existed, an importing country had no reliable way of finding out what an exporting country had approved, or on what evidence. It is now the operational backbone of the Article 11 procedure for commodities, since a party that approves a living modified organism for domestic use must post that decision there. Its weaknesses are also clear. Records are incomplete, because posting depends on national administrative capacity and willingness. Information is in practice dominated by a small number of active parties. And the system tells you what has been decided, not what is actually moving in trade. 8.2 Public awareness and participation Article 23 requires parties to promote and facilitate public awareness, education and participation concerning the safe transfer, handling and use of living modified organisms, to consult the public in the decision making process, and to make the results of decisions available to the public, while respecting confidential information. This obligation is easy to state and hard to fulfil. Public opinion on genetic modification is shaped by trust in institutions far more than by technical information, and a consultation exercise conducted after a decision has effectively been made will not build trust. Empirical work in Kenya found that awareness of the Protocol among stakeholders correlated only weakly with confidence in the adequacy of the legal framework, and that a large share of the public reported limited knowledge of the technology while holding strong concerns about environmental and health effects (Catherine, Mugiira, and Muchiri, 2024). Genuine #public_participation requires that the public be involved in framing the question, not merely in commenting on an answer. Article 21 protects confidential business information but expressly forbids treating the general description of the organism, the summary of the risk assessment, and methods and plans for emergency response as confidential. This is the compromise between commercial secrecy and public accountability, and it is generally regarded as reasonable. 8.3 Capacity building Article 22 obliges parties to cooperate in the development and strengthening of human resources and institutional capacities in biosafety, including biotechnology to the extent that it is required for biosafety, in developing country parties and parties with economies in transition. This provision was, for many developing countries, the reason for signing. A right to conduct a risk assessment is worthless if a country has no one able to conduct one. A great deal of international effort has gone into #capacity_building projects, including through the Global Environment Facility, and most parties now have some form of national biosafety framework on paper. The gap between paper and practice remains wide. Rabuma, Moronta-Barrios, and Craig (2024), surveying African regulators, found that although many African states adopted biosafety laws after joining the Protocol, most lack frameworks tailored to #genome_editing and #gene_drives, and that limited resources, limited expertise, limited public awareness and public resistance were the main obstacles to implementation. Ongu and colleagues (2023), comparing Kenya, Nigeria, Uganda and Sweden, found that the formal structure of the law was less important than the institutional capacity to run it: application processing times, the availability of trained reviewers, the cost to applicants and the coordination between agencies determined whether the framework functioned at all. The lesson is uncomfortable but important. Ratifying a treaty is cheap; operating one is expensive. A biosafety system needs a competent authority, a scientific advisory body, laboratories, inspectors at ports, a legal drafting capacity, and a public communication capacity. Very few countries in the world have all of these working well. 9. Compliance, Liability and Redress 9.1 The Compliance Committee Article 34 required the Meeting of the Parties to adopt procedures and mechanisms to promote #compliance and to address cases of non compliance. The resulting mechanism is facilitative rather than punitive. A Compliance Committee reviews cases, can offer advice, can facilitate assistance, and can report to the Meeting of the Parties, which may issue a caution or publish the case. There is no fine and no trade sanction. This is normal for multilateral environmental agreements. The logic is that most non compliance is caused by incapacity rather than by bad faith, and that assistance is more effective than punishment. The cost of that logic is that a party that simply does nothing faces very little consequence. The Compliance Committee has nevertheless played a quietly important role. In 2024 it drew the attention of the Meeting of the Parties to the fact that parties were interpreting the definition of a living modified organism differently, and that legislative approaches were diverging as a result of developments such as genome editing (Tsioumani and Rabitz, 2026). That is a compliance question in the deepest sense: if parties do not agree on what the treaty covers, they cannot be said to be applying the same treaty. 9.2 The Nagoya Kuala Lumpur Supplementary Protocol The question of what happens when something goes wrong was deferred in 2000 and answered, partially, in 2010. The #Nagoya_Kuala_Lumpur_Supplementary_Protocol on #Liability_and_Redress was adopted in Nagoya and entered into force on 5 March 2018. Its central mechanism is administrative rather than civil. Where damage to the conservation and sustainable use of biological diversity results from a living modified organism that finds its origin in a transboundary movement, the competent national authority may require the operator to take response measures, or may take those measures itself and recover the costs from the operator. Damage is defined as an adverse effect on the conservation and sustainable use of biological diversity that is measurable or otherwise observable, taking into account human health risks, and that is significant. The Supplementary Protocol is modest. It does not create an international liability fund. It does not create a private right of action in international law. It leaves the definition of significance, the standard of causation, and the treatment of financial security largely to domestic law. Critics regard it as a symbolic settlement of a demand that developing countries had pressed since the 1990s. Defenders point out that a modest, workable instrument in force is worth more than an ambitious one that never attracts ratifications. 10. The Protocol and the Trade Regime No aspect of the Protocol has generated more academic ink than its relationship with the law of the World Trade Organization. The problem is structural. The Protocol allows an importing state to restrict imports of a living modified organism on the basis of a risk assessment, and, where uncertainty remains, to restrict them precisely because the science is incomplete. Agreements administered by the #WTO, particularly the Agreement on the Application of Sanitary and Phytosanitary Measures, generally require that measures be based on scientific principles and not maintained without sufficient scientific evidence, permitting provisional measures only where relevant scientific evidence is insufficient and only for a reasonable period while additional information is sought. The two logics point in different directions. The Protocol handles this collision with deliberate ambiguity. Its preamble recites, in successive paragraphs, that trade and environment agreements should be mutually supportive, that the Protocol shall not be interpreted as implying a change in the rights and obligations of a party under any existing international agreements, and that this recital is not intended to subordinate the Protocol to other international agreements. Read together, these three paragraphs cancel each other out. They are a diplomatic agreement to disagree. In practice, an open conflict has not occurred, and the two regimes have coexisted through mutual avoidance. But the potential for conflict has grown rather than shrunk, because the deadlock in WTO dispute settlement has weakened the trade regime as an adjudicator, while divergence in the treatment of edited organisms is creating precisely the kind of asymmetric market access problem that trade law exists to police (Tsioumani and Rabitz, 2026). A country that treats an edited plant as an ordinary plant will export it as an ordinary plant. A country that treats it as a living modified organism will demand documentation that does not exist. That is a trade dispute waiting to happen, and it is also a biosafety failure waiting to happen. 11. Implementation in Practice 11.1 Uneven performance More than two decades of practice permit some general observations. Almost all parties have designated a competent national authority and a national focal point. A large majority have some form of biosafety law or regulation. Beyond that formal layer, performance diverges sharply. A small number of jurisdictions, including the European Union, Japan, Brazil, Argentina, China, India and South Africa, operate mature systems with functioning scientific advisory bodies, published assessments, and enforcement capacity. Japan gave domestic effect to the Protocol through a dedicated statute governing the use of living modified organisms, and its regulatory practice has become an important reference point in the debate about how edited organisms should be classified. A middle group has laws and institutions but limited throughput: applications are few, decisions are slow, and expertise is thin. Studies of Kenya, Nigeria and Uganda place these countries in this group, and identify the availability of trained reviewers and institutional coordination as the binding constraints (Ongu et al., 2023). A large group has ratified the Protocol but cannot operate it. For these parties the Protocol functions mainly as a source of default caution: since the state cannot assess an application properly, it does not approve one. 11.2 The non party problem The United States, the largest producer and exporter of #genetically_modified_crops, is not a party to the Convention on Biological Diversity and therefore not a party to the Protocol. Article 24 provides that transboundary movements between parties and non parties must be consistent with the objective of the Protocol, and encourages parties to conclude bilateral, regional or multilateral agreements with non parties. The practical result is that the largest source of living modified commodity exports lies outside the consent architecture, and that the Protocol governs those flows only indirectly, through the domestic law of importing parties. This is a structural weakness that no amount of institutional reform inside the regime can cure. 11.3 Convergence and divergence in national law Two opposite trends are visible. The first is convergence in the basic template. Nearly every national framework in the world now contains the same elements: a definition of a regulated organism, a permitting system distinguishing contained use, confined field trial and #environmental_release, a risk assessment requirement, a competent authority, and a public register. That template is a direct legacy of the Protocol and of the capacity building programmes built around it. The second is divergence in the treatment of new techniques. Argentina, Chile, Brazil, Japan, Canada, the United States, Australia, the Philippines, Kenya and several others have adopted approaches under which certain edited organisms, particularly those with small deletions and no inserted foreign DNA, are not regulated as genetically modified organisms at all, or are subject to a lighter consultation procedure (Zarate et al., 2023; Sanchez, 2024; Tachikawa and Matsuo, 2023). The European Union has historically applied its genetically modified organism legislation to organisms produced by mutagenesis techniques that lack a long safety record, and has since 2023 debated a distinct legal category for plants produced by #new_genomic_techniques (Vengadesen et al., 2025). New Zealand, India, China and others occupy intermediate positions, and the map changes every year. This divergence is the single most important development in biosafety law since the Protocol entered into force. It means that the same physical plant may be a regulated living modified organism in one country and an unregulated plant in the country next door, with all that implies for #trade, for documentation, and for the coherence of the regime. 12. The New Biotechnologies and the Limits of the 2000 Text 12.1 Genome editing and the definitional crisis The definition in Article 3 was written for transgenesis. It asks whether an organism possesses a novel combination of genetic material obtained through in vitro nucleic acid techniques that overcome natural barriers. #Genome_editing does not fit this frame comfortably. Techniques based on #CRISPR associated proteins can be used to make a small, targeted change, such as knocking out a gene, that is indistinguishable from a mutation that could have arisen spontaneously or through chemical mutagenesis, which is an accepted conventional breeding method. The editing reagents may be delivered in vitro, but the final plant may contain no foreign DNA at all and no novel combination of genetic material in any meaningful sense. Three interpretive positions have emerged. The process based position holds that the technique used was an in vitro nucleic acid technique, so the product is a living modified organism, full stop. The product based position holds that if the resulting organism could have been produced by conventional breeding and contains no foreign DNA, it is not a living modified organism and should not be regulated as one. The intermediate position distinguishes among categories of edit, typically treating edits that only disrupt a gene differently from edits that insert a template or foreign sequence. The consequences of this disagreement are not academic. They determine whether a shipment requires advance informed agreement, whether documentation must accompany it, whether a risk assessment is required, and whether an importing state may lawfully refuse it. Vengadesen, Abdul Aziz, and Jones (2025) describe the resulting situation as a legal grey area, and argue that neither a rigid process trigger nor a pure product test is adequate; they favour a principle based approach in which high level regulatory principles, such as proportionality of oversight to plausible risk, are applied case by case and can absorb new techniques without repeated legislative amendment. Others reject that approach on the ground that principles without rules become whatever the regulator wishes them to be. The governing body has so far declined to settle the question. In 2024 it merely encouraged parties to submit information about national legislation on new developments in modern biotechnology to the #Biosafety_Clearing_House (Tsioumani and Rabitz, 2026). Encouragement is not interpretation. In the meantime, national divergence hardens. 12.2 Gene drives An engineered #gene_drive is a genetic element designed to be inherited by far more than the ordinary half of offspring, so that it spreads through a wild population over successive generations even if it reduces the fitness of the individuals carrying it. Drives are being developed to suppress mosquito populations that transmit malaria and dengue, and to control #invasive_alien_species such as rodents on islands. Gene drives break several of the assumptions on which the Protocol was built. The Protocol is built around a bilateral transaction, an export and an import, with a decision point at the border. A drive organism is designed to spread by itself, and mosquitoes do not present documentation at customs. The Protocol assumes a receiving environment that can be characterised in advance. A drive is intended to change the receiving environment. The Protocol assumes that a decision can be reviewed and, in principle, reversed under Article 12. A drive that has spread cannot be recalled. The response of the regime has been cautious and, in the view of many observers, thin. The Meeting of the Parties in 2022 agreed to develop voluntary risk assessment guidance for gene drive systems, with a focus on gene drive mosquitoes. In 2024 it welcomed the resulting additional voluntary guidance materials rather than adopting them, and identified no further areas needing specific guidance (Tsioumani and Rabitz, 2026). The guidance is therefore soft law about one taxon, produced by a treaty whose binding Annex III remains unchanged, at a time when drives are also being explored for rodents and other organisms. There is a legal alternative that the parties have not taken, namely amending Annex III, which is binding, to add mandatory criteria for organisms designed to spread. The choice of voluntary guidance over binding amendment is the clearest illustration of the softening trend discussed below. 12.3 Living modified fish and the aquatic environment Living modified fish are of growing commercial interest, and the aquatic environment poses distinctive biosafety questions: mobility, the difficulty of containment, the possibility of hybridisation with wild populations, and the ease with which organisms cross national boundaries in shared water bodies. Okoli and colleagues (2022) review the biosafety implications of using CRISPR based methods in aquaculture and identify significant gaps in existing assessment methodology. Despite this, the expert group under the Protocol concluded that specific guidance for living modified fish was not needed, and the Meeting of the Parties did not pursue it (Tsioumani and Rabitz, 2026). This is difficult to defend on scientific grounds and is best explained by the political economy of the negotiation. 12.4 Synthetic biology and digital sequence information #Synthetic_biology is an umbrella term rather than a technique. The operational description used under the Convention treats it as a further development and new dimension of modern biotechnology that combines science, technology and engineering to facilitate and accelerate the understanding, design, redesign, manufacture or modification of genetic materials, living organisms and biological systems. Read literally, that covers almost everything now being done in the life sciences. Two governance problems follow. The first is scope. If synthetic biology organisms are living modified organisms, the Protocol applies. If a designed organism is assembled from synthesised DNA with no identifiable recipient or donor organism, the Annex III methodology, which compares the modified organism with its unmodified parent, has nothing to compare it with. The methodology assumes a parent that may not exist. The second is #digital_sequence_information. Once a sequence has been read and stored digitally, it can be transmitted across a border as data and reconstructed as an organism at the destination. No physical shipment crosses the frontier and therefore no #transboundary_movement, in the sense the Protocol uses that term, has occurred. The whole architecture of border consent is bypassed. Digital sequence information has been treated under the Convention mainly as a benefit sharing question, resulting in a decision at the fifteenth Conference of the Parties in 2022 to establish a multilateral mechanism, and modalities for a global fund agreed in 2024 (Akpoviri, Baharum, and Zainol, 2023; Klunker and Richter, 2022; Tsioumani and Rabitz, 2026). Its biosafety implications have received far less attention, and that is a gap. The expert work under the Convention has identified priority items for future consideration, including gene drive systems for large scale in situ genetic engineering, self spreading vaccines for use in wildlife, and the convergence of synthetic biology with artificial intelligence. The sixteenth Conference of the Parties in 2024 did not act on that list, gave priority to the potential positive impacts of synthetic biology and to capacity building, and merely noted the expert work (Tsioumani and Rabitz, 2026). 12.5 The de-legalisation trend Taken together, these developments describe a pattern. On the three biotechnology issues that have dominated the agenda over the past decade, digital sequence information, risk assessment of new types of living modified organism, and synthetic biology, the outcomes have been characterised by weak legal obligation, imprecise wording and reduced institutionalisation. Tsioumani and Rabitz (2026) call this de-legalisation, borrowing the vocabulary of the legalisation literature, in which the degree of legalisation of an international arrangement is measured by obligation, precision and delegation. On all three dimensions, biotechnology rule making under the Convention has moved backwards since around 2010. Rules that are welcomed rather than adopted, that invite rather than require, and that describe indicative rather than binding lists, produce little behavioural change. The drivers they identify are political rather than scientific. The geography of biotechnology has changed. In the 1990s most developing countries had no biotechnology sector and supported strict international regulation of a technology whose benefits accrued to others. Today Brazil, China, India and a growing number of African states are producers as well as importers, and their interest has shifted from restricting risk to sharing benefit. The European Union, once the driver of precautionary regulation, is itself debating the deregulation of some edited crops. Civil society attention has moved from genetic modification to climate change. The #Kunming_Montreal_Global_Biodiversity_Framework, adopted in 2022, contains no reference to precaution, and its biosafety target largely restates the language of the Convention rather than setting a measurable goal. This is the central diagnosis of the present article. The Protocol is not failing because its rules are being broken. It is losing force because its rules are not being extended to the things that now matter most. 13. Assessment: What the Protocol Has and Has Not Achieved 13.1 Achievements Four achievements can be claimed with confidence. The first is normative. The Protocol established, as a matter of binding international law, that a state has the right to be informed and the right to decide before living modified organisms enter its territory, and that it may act under uncertainty. Before 2000 this was contested. It is now the baseline. The second is architectural. The template of a national biosafety framework, a competent authority, a permitting system, a risk assessment requirement and a public register, now exists in the great majority of countries, and it exists because of the Protocol and the capacity programmes built around it (Rabuma, Moronta-Barrios, and Craig, 2024). The third is informational. The Biosafety Clearing House created a global public record of biosafety decisions where none existed. The fourth is procedural. Annex III remains a defensible, scientifically respectable framework for the case by case, comparative, environment specific assessment of an introduced organism. Its core logic, comparing the modified organism with the unmodified parent in the actual receiving environment, has held up better than many of its critics predicted. 13.2 Shortcomings Five shortcomings must equally be acknowledged. The first is the commodity exemption. The category of organisms intended for food, feed or processing, which covers the great majority of world trade in living modified material, escapes the consent procedure. The documentation rules for that category, even after improvement, remain weaker than for seed. The second is capacity. A treaty that grants a right to conduct a risk assessment to states that cannot conduct one grants a right that cannot be exercised. Capacity building has been real but insufficient, and the arrival of techniques that require sophisticated molecular detection widens the gap rather than narrowing it. The third is enforcement. The compliance mechanism is facilitative, liability is administrative and thinly specified, and there is no meaningful consequence for a party that does nothing. The fourth is coverage. The largest exporter of living modified crops is not a party, and organisms produced by the newest techniques may not be covered at all, depending on whose interpretation of Article 3 prevails. The fifth, and the most serious, is adaptive failure. The regime has responded to twenty five years of scientific transformation with voluntary guidance on one species of mosquito. Annex III has not been amended. The definition of a living modified organism has not been clarified. The parties have chosen, repeatedly, not to decide. 13.3 A note on proportion It is worth stating plainly that the empirical record of harm from commercially cultivated genetically modified crops over three decades has not matched the more alarming predictions made in the 1990s. Most of the specific ecological catastrophes that were predicted have not occurred, and comprehensive reviews of the agronomic and environmental record identify trade offs rather than disasters (Caradus, 2023). A responsible assessment of the Protocol must acknowledge this, because a regulatory regime that cannot update its threat model in the light of evidence is as defective as one that ignores risk. But two qualifications matter. First, the absence of observed harm in the crops that were assessed is partly an outcome of the assessment, not merely an argument against it; the counterfactual is unknowable. Second, and more importantly, the risk profile of the new technologies is not the risk profile of the old ones. A herbicide tolerant soybean grown in a country with no wild relatives is a different kind of object from a gene drive engineered to sweep through a wild population, or a self spreading vaccine released into wildlife. It is precisely the fact that the old debate has cooled, while the new technologies are more consequential, that makes the current softening of the regime so poorly timed. 14. Reform Pathways The following proposals are offered as a research agenda and a policy agenda. They are ordered from the most legally demanding to the most immediately practicable. 14.1 Clarify the definition of a living modified organism The parties should resolve, through an authoritative interpretation or through an amendment to Article 3, whether and when organisms produced by #new_genomic_techniques fall within the definition. Any of the three available answers, process based, product based or tiered, would be better than the present silence, because the present silence is itself an answer: it means that each party decides for itself, and the regime fragments. A tiered approach appears the most likely landing zone. It would treat organisms containing stably inserted foreign genetic material as living modified organisms in the full sense; treat organisms whose edits are confined to the removal or alteration of native sequence, with no foreign DNA remaining, under a notification and confirmation procedure rather than full advance informed agreement; and reserve the strictest treatment, including mandatory international consultation, for organisms designed to spread in the wild. This has the merit of aligning regulatory burden with plausible risk, which is the principle that both critics and defenders of the current system claim to accept. 14.2 Modernise Annex III Annex III is binding and amendable. It should be amended to add mandatory considerations for organisms that are designed to persist and spread, including engineered gene drives; for organisms intended for release into aquatic environments; and for organisms with no identifiable conventional parent, where the comparative logic of the current methodology fails. Voluntary guidance materials are useful as technical support, but they cannot substitute for binding criteria, because a voluntary standard that is inconvenient will simply not be used. 14.3 Treat detection as an obligation, not an aspiration A documentation regime is only as strong as the ability of the importing state to verify what has arrived. The parties should agree a work programme on #detection_and_identification and #traceability, including reference materials, validated methods for edited organisms, unique identifier systems that extend to edited events, and regional reference laboratories serving groups of countries that cannot each maintain their own. This is expensive but it is the difference between a legal right and a real one. 14.4 Rebuild capacity around throughput, not paperwork Capacity building should be measured by the ability of a national system to process an application competently and within a defined time, not by the number of workshops delivered or draft laws produced. That means sustained funding for salaries and laboratories, regional pooling of scientific expertise, and mutual recognition arrangements that allow a small state to rely on a rigorous assessment conducted elsewhere while retaining the right to decide on its own receiving environment (Ongu et al., 2023; Rabuma et al., 2024). 14.5 Take socio-economic considerations seriously Article 26 permits parties, in reaching a decision on import, to take into account #socio_economic_considerations arising from the impact of living modified organisms on the conservation and sustainable use of biological diversity, especially with regard to the value of biological diversity to indigenous and local communities. This provision has been under used, partly because there is no agreed methodology for assessing socio economic impact and partly because exporting states have resisted its expansion. Yet the socio economic dimension is precisely where public concern is concentrated: seed sovereignty, market concentration, the fate of smallholder farmers, the position of centres of crop origin, and the ownership of intellectual property. A regime that refuses to address these questions cannot credibly claim to have addressed the concerns of the societies it governs. Developing a transparent, bounded methodology for socio economic assessment, one that does not become a licence for arbitrary protectionism, is one of the most valuable pieces of work the regime could now commission. 14.6 Reconnect biosafety with the biodiversity agenda The absence of precaution from the Kunming Montreal Global Biodiversity Framework, and the weakness of its biosafety target, reflect the drift of biosafety to the margins of the biodiversity agenda. Biosafety should be re anchored to that agenda by linking the biosafety target to measurable indicators, such as the proportion of parties with functioning risk assessment capacity, the proportion of decisions posted to the Biosafety Clearing House, and the existence of national detection capability. 14.7 Address digital sequence information as a biosafety question The debate about digital sequence information has been conducted almost entirely in the language of benefit sharing. It should also be conducted in the language of biosafety, because sequence data that can be reconstructed into an organism at the destination is functionally a transboundary movement in all but the legal sense. At minimum, the parties should commission an assessment of whether, and how, the border consent logic of the Protocol can survive the digitisation of biology. 15. Implications for Students and Researchers For students, the Cartagena Protocol is an unusually good teaching case, because it makes visible the joints of international law that are usually hidden. It shows how scientific uncertainty is converted into legal rules. It shows how a treaty text is a photograph of a political balance at one moment, and how the passage of time turns compromise language into ambiguity. It shows the difference between formal ratification and operational compliance, which is the central lesson of implementation studies. It shows how a regime can succeed normatively while under performing operationally. And it shows, in the debate about genome editing, how the definitions chosen at the outset can determine the fate of a regime decades later, because a treaty can only regulate the things it defined. Several research questions remain open and are suitable for postgraduate work. What is the actual rate of compliance with the documentation requirements of Article 18, as measured at ports rather than in reports? What has been the effect of divergent national treatment of edited crops on trade flows and on the seed sector in importing countries? Does the presence of a functioning national biosafety framework measurably affect the rate of technology adoption, positively or negatively? Can a workable methodology for socio economic assessment be designed that survives both scientific and trade law scrutiny? And what governance instrument, if any, can regulate an organism designed to spread across borders on its own? 16. Conclusion The Cartagena Protocol on Biosafety was an achievement of its time. It took a technology that frightened many people and a trade that enriched a few, and it built around them a legal structure based on three propositions: that an importing state has the right to know, the right to assess, and the right to decide. It embedded a #precautionary_approach in a binding treaty and made it operational rather than rhetorical. It created an information infrastructure. It seeded national regulatory systems in more than a hundred and seventy countries. Those are not small things. The Protocol is now, however, in a difficult position. The science it governs has changed more in the past ten years than in the twenty before them. The organisms that raise the sharpest questions, edited plants that contain no foreign DNA, gene drives designed to spread through wild populations, organisms designed from digital sequences and assembled anywhere, do not fit comfortably inside a definition drafted in the 1990s or a procedure built around a shipping container. And the response of the parties has been to soften rather than to sharpen: voluntary guidance instead of binding criteria, information gathering instead of interpretation, capacity building instead of rule making. The risk is not dramatic non compliance. The risk is quiet irrelevance. A treaty that is not extended becomes, over time, a treaty that governs a shrinking share of the activity it was created to govern. The remedy is not to make the Protocol more restrictive, nor to make it more permissive. It is to make it more precise. A regime that says clearly what it covers, that scales oversight to plausible risk, that gives importing states a real rather than a formal ability to assess what arrives at their borders, and that says something binding about organisms designed to spread, would serve both the innovation agenda and the conservation agenda better than the present ambiguity serves either. #Biosafety governance does not need a new treaty. It needs the courage to finish the one it has. 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The Convention on Biological Diversity (CBD), opened for signature at the Rio Earth Summit in 1992, is the principal #multilateral_treaty through which states have tried to slow the loss of life on Earth while keeping the door open to development. This article offers a structured, student-friendly review of the Convention: what it says, how it works, what it has achieved, and where it has failed. Using a narrative review of primary treaty texts, decisions of the Conference of the Parties, and peer-reviewed literature published mainly between 2021 and 2026, the paper traces the Convention from its three founding objectives (#conservation, #sustainable_use, and fair and equitable #benefit_sharing) through its two protocols (Cartagena and Nagoya) to the adoption of the Kunming-Montreal Global Biodiversity Framework (GBF) in 2022 and the operational decisions taken at COP16 in Cali and Rome in 2024 and 2025. Four findings stand out. First, the CBD has achieved near universal membership and has successfully framed biodiversity as a matter of international law rather than charity, but it remains a framework treaty with weak compliance machinery. Second, the failure to meet a single Aichi Biodiversity Target by 2020 was a failure of national implementation and finance, not of scientific knowledge. Third, the GBF has repaired some of the design faults of the Aichi period by adding a #monitoring_framework, a ratchet-style review cycle and quantified finance targets, yet early evidence suggests that national plans are still not ambitious enough. Fourth, the new multilateral mechanism on digital sequence information, including the Cali Fund, is the most important institutional innovation in the Convention since 2010, and its success or failure will shape the credibility of the whole regime. The article closes with a research agenda for students and early-career scholars. Keywords: Convention on Biological Diversity; global environmental governance; Kunming-Montreal Global Biodiversity Framework; access and benefit-sharing; digital sequence information; biodiversity finance; protected areas; sustainable development 1. Introduction Biological diversity is the variety of life at every level, from #genes to species to whole ecosystems. It underpins food systems, medicine, water security, #climate_regulation and cultural identity. It is also disappearing at a rate that has no parallel in recorded human history. The scale of that loss is why the international community negotiated the #Convention_on_Biological_Diversity, a treaty that was opened for signature at the #Rio_Earth_Summit in Rio de Janeiro on 5 June 1992 and entered into force on 29 December 1993. The Convention is unusual among environmental treaties. Most environmental agreements before it were narrow. Some protected a single species group, such as migratory birds or whales. Some protected a single habitat type, such as wetlands. Some regulated a single problem, such as trade in endangered species or the release of ozone-depleting chemicals. The CBD was the first legally binding global agreement to treat biodiversity as a whole and to link its protection directly to #economic_development and to the rights of the countries where that diversity is concentrated (Hughes and Grumbine, 2023). That linkage was not accidental. It was the political price of the treaty. Countries in the tropics hold most of the world's species; countries in the industrialised north held most of the capital and most of the biotechnology industry that wanted access to those species. The Convention resolved this tension with a bargain: states have #sovereign_rights over the biological resources within their borders, but they accept a duty to conserve those resources and to use them sustainably, and in return they are entitled to a fair share of the benefits that arise when others use their #genetic_resources. This bargain is written into the Convention's three objectives and it explains almost every subsequent controversy in the regime, including the fight over digital genetic data that dominated negotiations more than thirty years later. Today the Convention has 196 Parties. This includes almost every state in the world and the European Union. The United States signed the Convention in 1993 but has never ratified it, which means it participates in meetings as an observer rather than as a Party. Near universal membership gives the CBD unmatched legitimacy as the forum where the world talks about #biodiversity_loss. It does not, by itself, give the Convention power. That distinction between legitimacy and power sits at the centre of this article. 1.1 Why this topic matters now Three things make 2026 an unusually good moment to take stock of the Convention. The first is that the world has just entered the second half of the delivery period for the Kunming-Montreal Global Biodiversity Framework. The GBF, adopted in Montreal in December 2022 under the presidency of China, contains four long-term goals for 2050 and 23 action-oriented targets for 2030 (Hughes and Grumbine, 2023; Affinito et al., 2024). Targets that were treated as distant in 2023 are now urgent. Several, such as the identification of harmful subsidies, had deadlines in 2025 that have already passed. The second is that COP16, held in Cali, Colombia in October and November 2024 and completed in Rome in February 2025, took the decisions that turn the GBF from a declaration into an administrative system. Parties agreed the full set of #indicators for the monitoring framework, agreed a planning, monitoring, reporting and review mechanism, adopted a #resource_mobilisation strategy, established a new permanent subsidiary body on Article 8(j) for #Indigenous_Peoples and local communities, and operationalised a multilateral benefit-sharing mechanism for digital sequence information that includes the #Cali_Fund. The third is that COP17 will take place in Yerevan, Armenia, from 19 to 30 October 2026, and will host the first #global_review of collective progress towards the GBF. For the first time, Parties will look at the aggregate picture produced by national reports and national plans and ask whether the world is on track. The honest expectation, based on the evidence reviewed below, is that it is not. 1.2 Aim, scope and contribution This article has a simple aim: to give students a complete but readable account of the CBD as an instrument of #global_governance, and to equip them to think critically about it rather than to memorise its structure. The scope is the Convention itself, its two protocols, the strategic plans adopted under it, and the institutional machinery through which it operates. The article does not attempt a comprehensive ecological review of biodiversity decline; that literature is enormous and is well covered elsewhere. Where ecological data appear, they appear as evidence about whether the treaty is working. The contribution is threefold. First, the article integrates legal, political and scientific literatures that are usually kept separate, which is where most undergraduate confusion begins. Second, it uses very recent peer-reviewed sources, including analyses of the COP16 outcomes and of the first wave of revised national plans, so that students are not working from a picture of the regime that is already out of date. Third, it sets out a research agenda that identifies where the evidence is genuinely thin. 1.3 Research questions The article is organised around five questions. What legal and political bargain does the CBD actually contain, and how has that bargain shaped its evolution? How do the Cartagena and Nagoya Protocols extend the Convention, and what have they achieved? Why did the Aichi Biodiversity Targets fail, and does the Kunming-Montreal Global Biodiversity Framework fix the causes of that failure? Is the finance architecture of the Convention adequate to its ambitions? What should students and researchers watch between now and 2030? 2. Background and Literature Review 2.1 The road to Rio The CBD did not emerge from nothing. By the late 1980s a patchwork of agreements already existed. The Ramsar Convention on Wetlands dated from 1971. The World Heritage Convention followed in 1972. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was concluded in 1973 and the Convention on Migratory Species in 1979. Each of these worked on a fragment of the problem. The trouble with a fragmented system is that it protects lists rather than systems. A species can be listed under CITES and still go extinct because its forest is cleared for agriculture. A wetland can be listed under Ramsar and still die because the river feeding it is dammed upstream. By the 1980s scientists and lawyers were arguing for a treaty that dealt with #ecosystems and with the drivers of loss rather than with symptoms. The United Nations Environment Programme convened a working group in 1988 and then an intergovernmental negotiating committee. The text was agreed in Nairobi in May 1992 and opened for signature three weeks later at the United Nations Conference on Environment and Development in Rio de Janeiro. The same summit produced the United Nations Framework Convention on Climate Change and the framework that became the United Nations Convention to Combat Desertification. Together these are often called the #Rio_Conventions. The simultaneous birth of the climate and biodiversity treaties matters. It created two parallel regimes with separate secretariats, separate scientific bodies, separate finance channels and separate national focal points, dealing with two crises that are physically inseparable. Bringing them back together is one of the main tasks of contemporary environmental governance (Portner et al., 2023). 2.2 The literature on the CBD: three traditions The scholarship on the Convention falls into three broad camps, and students should be able to tell them apart because they ask different questions and reach different conclusions. The legal and institutional tradition asks what the Convention obliges states to do, how its language should be interpreted, and how its bodies function. Work in this tradition tends to emphasise the softness of the Convention's obligations. Article 6, for example, requires each Party to develop national strategies "in accordance with its particular conditions and capabilities" and to integrate biodiversity into sectoral plans "as far as possible and as appropriate". Qualifiers of this kind appear throughout the text and they give Parties enormous discretion. Recent legal analysis of the GBF's restoration target makes the same point in a modern setting: even the flagship targets need careful legal interpretation before anyone can say what a country has actually promised (Bell-James and Watson, 2025). The political economy tradition asks who wins and who loses. It examines the #north_south_bargain at the heart of the treaty, the distribution of the costs of conservation, and the persistent gap between what developing countries were promised and what they received. Recent work has begun to apply explicit theories of #distributive_justice to the GBF, asking whether costs should fall on those who can pay, those who benefit, or those who caused the damage, and showing that the Framework never resolves this question (Lehmann et al., 2025). A parallel strand argues that biodiversity targets cannot be separated from broader questions of #Earth_system_justice (Gupta et al., 2023). The conservation science tradition asks whether the targets are ecologically meaningful and whether they can be measured. This literature has been consistently critical. It argues that many targets are vague, that indicators are missing or inconsistent, and that the data infrastructure needed to monitor a global framework does not yet exist in most countries (Hughes, 2023a; Gonzalez et al., 2023; Affinito et al., 2025). A student who reads only one of these three traditions will get a distorted picture. Lawyers tend to conclude that the regime is weak but improving. Political economists tend to conclude that it is a mechanism for managing conflict rather than solving it. Scientists tend to conclude that it is unmeasurable. All three are partly right. 2.3 The state of biodiversity: the evidence base The Convention exists because of an empirical claim: that biodiversity is declining fast and that the decline is caused by human activity. That claim is now among the best supported in environmental science. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is the body that assembles this evidence, playing a role for biodiversity comparable to the role played by the Intergovernmental Panel on Climate Change for the atmosphere. Its assessments identify five direct drivers of loss: changes in land and sea use, direct exploitation of organisms, #climate_change, pollution, and #invasive_alien_species. IPBES has also examined the values people place on nature and, in its 2024 assessments, the interlinkages between biodiversity, water, food and health and the conditions under which #transformative_change becomes possible (IPBES, 2022; IPBES, 2023; IPBES, 2024a; IPBES, 2024b). Population trend data reinforce the picture. The Living Planet Index, which tracks the average change in monitored wildlife populations rather than the number of species lost, reported an average decline of about 73 per cent in monitored vertebrate populations between 1970 and 2020, with freshwater populations declining fastest (WWF, 2024). The index is frequently misread; it does not mean that 73 per cent of animals have vanished. It means that the average monitored population has shrunk by that proportion. Students should be careful with this distinction, because critics of the index have attacked precisely the sloppy readings of it rather than the underlying data. Two conclusions follow. The scientific case for action is not the weak link in the chain. The weak link is #implementation. 3. Methodology This article is a structured #narrative_review combined with #document_analysis. It is not a systematic review in the technical sense, and it does not claim to be exhaustive. 3.1 Sources Three categories of material were used. Primary treaty texts and decisions. These include the text of the Convention on Biological Diversity (1992), the Cartagena Protocol on Biosafety (2000), the Nagoya Protocol on Access and Benefit-Sharing (2010), the Strategic Plan for Biodiversity 2011 to 2020 with its Aichi Biodiversity Targets, decision 15/4 adopting the Kunming-Montreal Global Biodiversity Framework, and the decisions adopted at COP16 in Cali and at its resumed session in Rome, in particular decision 16/2 on digital sequence information. Peer-reviewed literature. Searches were conducted for articles published between 2021 and 2026 in journals covering conservation biology, environmental law, environmental policy and global governance. Priority was given to work published after the adoption of the GBF, because analyses written before December 2022 necessarily speculate about a text that had not yet been agreed. Institutional reports. These include the Protected Planet Report 2024, IPBES assessment reports, and reports of the biodiversity finance literature. 3.2 Analytical framework The material was analysed against four criteria that are standard in the study of international regimes. #Ambition: how demanding are the commitments in the text? #Precision: how clearly are they expressed, and could a court or a reviewer tell whether they had been met? #Delegation: how much authority is given to institutions to interpret, monitor and enforce? #Delivery: what has actually changed on the ground? A regime can score high on ambition and low on everything else. Readers will see that this describes the CBD rather well. 3.3 Limitations Three limitations should be stated openly. First, the review depends on official reporting, and official reporting is uneven; countries with weak statistical capacity are under-represented in every dataset used here. Second, the GBF is young, and the absence of evidence of impact after four years is not evidence of absence of impact; ecological responses lag policy by years or decades. Third, the literature on the Convention is dominated by authors based in Europe, North America, China and Australia, which introduces a geographical bias into the critical consensus that this article inevitably inherits. 4. The Architecture of the Convention 4.1 The three objectives Article 1 of the Convention states three objectives, and everything else follows from them. The first is the #conservation of biological diversity. The second is the sustainable use of its components. The third is the fair and equitable sharing of the benefits arising out of the utilisation of genetic resources, including by appropriate access to genetic resources, appropriate transfer of relevant technologies, and appropriate funding. These three are not independent. They are a package, and they were negotiated as a package. Developing countries would not accept obligations to conserve unless the treaty also recognised their right to develop and their right to benefit. Industrialised countries would not accept benefit-sharing obligations unless the treaty also secured access to genetic resources. Remove any one leg and the table falls over. This is why the CBD Secretariat insists that the three objectives must be pursued "in a balanced manner", a phrase that appears in the GBF itself. Students often underestimate the third objective, treating it as a technical footnote. It is not. It is the reason the Convention exists in its current form, it produced the Nagoya Protocol, and it produced the longest and hardest fight in the treaty's recent history, over digital sequence information. 4.2 Sovereignty and the common concern Article 3 reaffirms that states have "the sovereign right to exploit their own resources pursuant to their own environmental policies". The preamble simultaneously affirms that the conservation of biological diversity is "a common concern of humankind". That phrase was chosen with care. An earlier proposal would have declared biodiversity the "common heritage of mankind", the formula used for the deep seabed and for outer space. Common heritage implies collective ownership and international management. Biodiversity-rich states rejected it, because it would have implied that their forests were not theirs. "Common concern" is much weaker. It creates a shared interest and, arguably, a shared duty to cooperate, but it leaves ownership and control firmly with the territorial state. This single drafting choice explains a great deal. It explains why the Convention cannot compel a country to protect a forest. It explains why access to genetic resources requires the prior informed consent of the providing country. And it explains why the finance question is so bitter: if conservation is a national responsibility but a global benefit, then someone has to pay the country that forgoes the timber revenue, and the Convention never says clearly who. 4.3 The substantive obligations Articles 6 to 20 contain the operational commitments. The most important for students are these. Article 6 requires each Party to develop national strategies, plans or programmes for the conservation and sustainable use of biological diversity and to integrate biodiversity into relevant sectoral and cross-sectoral plans. This is the legal basis for #NBSAPs, the National Biodiversity Strategies and Action Plans, which are the main vehicle for implementation. Article 7 requires identification and monitoring of components of biodiversity and of processes likely to have adverse impacts. Article 8 covers in-situ conservation: protected areas, ecosystem restoration, control of invasive alien species, and regulation of living modified organisms. Article 8(j) is the provision on the knowledge, innovations and practices of Indigenous Peoples and local communities. It is short, it is heavily qualified, and it has generated an entire institutional apparatus. Article 9 covers ex-situ conservation, such as gene banks, botanical gardens and captive breeding. Article 10 covers sustainable use, including the protection of customary use consistent with conservation requirements. Article 14 requires #environmental_impact_assessment for projects likely to have significant adverse effects on biodiversity. Article 15 governs access to genetic resources. It recognises the authority of national governments to determine access, subject to prior informed consent, on mutually agreed terms. Articles 16 to 19 cover technology transfer, information exchange, technical cooperation and the handling of biotechnology, including the provision that eventually gave rise to the Cartagena Protocol. Article 20 covers financial resources, and it is the provision that has caused more argument than any other. It requires developed country Parties to provide "new and additional financial resources" to enable developing country Parties to meet the "agreed full incremental costs" of implementation. The phrase "agreed full incremental costs" has never been defined to anyone's satisfaction. Notice the pattern. Almost every obligation is qualified. Parties act "as far as possible and as appropriate". This is what lawyers mean when they call the CBD a framework convention: it establishes a system, a set of principles and a forum for further negotiation, rather than a set of hard rules. 4.4 The institutions The #Conference_of_the_Parties (COP) is the governing body. It meets every two years and takes decisions by consensus, which in practice means that any single Party can block agreement. Consensus produces legitimacy and paralysis in roughly equal measure. The Secretariat, based in Montreal, services the Convention. The Subsidiary Body on Scientific, Technical and Technological Advice (SBSTTA) provides scientific advice. Unlike the IPCC, it is a body of government-nominated experts, which means its outputs are negotiated rather than purely scientific. The creation of IPBES in 2012 partly filled the resulting gap. The Subsidiary Body on Implementation (SBI), created in 2014, reviews progress and prepares the review cycle. The #financial_mechanism is operated by the #Global_Environment_Facility. Since 2023 it has been joined by the Global Biodiversity Framework Fund (GBFF), a dedicated fund created to channel money towards the GBF. Since COP16 there is also a new permanent subsidiary body on Article 8(j), giving Indigenous Peoples and local communities a standing institutional role in the Convention rather than an ad hoc working group. This is a genuinely significant reform, and it is the first of its kind in a major multilateral environmental agreement. 5. The Protocols 5.1 The Cartagena Protocol on Biosafety (2000) The Cartagena Protocol was adopted in January 2000 and entered into force on 11 September 2003. It has 173 Parties and rests on the regulation of #biosafety. It regulates the transboundary movement, transit, handling and use of living modified organisms (#LMOs) produced by modern biotechnology that may have adverse effects on biodiversity, taking into account risks to human health. Its central mechanism is the #advance_informed_agreement procedure. Before an LMO intended for intentional introduction into the environment is exported for the first time, the exporter must notify the importing country, and the importing country may accept, refuse or impose conditions. The Protocol also establishes the Biosafety Clearing-House, an information exchange system, and it applies the #precautionary_approach: lack of scientific certainty about the extent of a potential adverse effect is not a reason to avoid taking a decision to prevent that effect. The Protocol is supplemented by the Nagoya-Kuala Lumpur Supplementary Protocol on Liability and Redress, adopted in 2010, which addresses what happens when damage does occur. Assessments of the Cartagena Protocol are mixed. It has built biosafety capacity in dozens of countries that previously had none, and it has given importing states a legal right to say no. Critics argue that its coverage of LMOs intended for direct use as food, feed or processing is much weaker than its coverage of LMOs for release, and that new gene-editing techniques sit awkwardly within definitions written in the 1990s. That question, usually discussed under the heading of #synthetic_biology, is on the agenda for COP17. 5.2 The Nagoya Protocol on Access and Benefit-Sharing (2010) The Nagoya Protocol was adopted on 29 October 2010 and entered into force on 12 October 2014. As of 2025 it has around 142 Parties, and it is the core instrument of the #ABS regime. Its purpose is to give operational effect to the third objective of the Convention. The logic is simple. A pharmaceutical company wants to study a plant from a tropical forest. Under the Protocol, it must obtain the prior informed consent of the providing country, and it must agree #mutually_agreed_terms setting out how benefits will be shared if the research produces something valuable. Benefits may be #monetary_benefits, such as royalties or milestone payments, or #non_monetary_benefits, such as joint research, training, #technology_transfer or sharing of results. The Protocol also addresses traditional knowledge. Where Indigenous Peoples and local communities hold traditional knowledge associated with genetic resources, Parties are to take measures to ensure that the knowledge is accessed with their prior informed consent and that benefits are shared with them. Compliance rests on two pillars. Each Party designates a national focal point and a competent national authority. Each Party must also designate checkpoints, at which users must show that they have complied with access requirements, and the Access and Benefit-Sharing Clearing-House issues internationally recognised certificates of compliance. The Protocol's record is contested. Supporters point out that it converted an abstract principle into an enforceable transaction and that it has made #biopiracy a legal wrong rather than a rhetorical complaint. Critics, including many scientists, argue that the administrative burden has slowed non-commercial research, that permits can take years, and that the volume of money actually shared has been modest relative to the effort involved (Beato and Veneroso, 2023). A systematic review of national access and benefit-sharing policies found wide variation in design and considerable inconsistency across jurisdictions, which raises transaction costs for everyone (Ljungqvist et al., 2025). There is also a structural problem that the drafters did not anticipate, and it nearly broke the regime. 5.3 Digital sequence information and the Cali Fund The Nagoya Protocol regulates access to physical genetic resources. But biotechnology has moved on. Today a researcher rarely needs the plant. She needs its sequence, and that sequence is very likely to be in a public database, uploaded by someone else, freely downloadable anywhere in the world. This is #digital_sequence_information, or DSI. If DSI falls outside the scope of the Protocol, then the entire benefit-sharing bargain can be bypassed without breaking any rule. Provider countries saw this clearly, and from 2016 onwards they refused to let the issue drop. User countries and much of the scientific community were equally clear that restricting access to open sequence databases would damage public science, pandemic preparedness and biodiversity research itself. The way out was proposed in the scientific literature before it was adopted in the treaty. Rather than trying to trace every sequence back to a country of origin, which is technically and legally impractical, a multilateral system could decouple access from benefit-sharing: keep the databases open, and collect contributions from commercial users into a common fund that is then distributed for conservation and for capacity building (Scholz et al., 2022). This is essentially what Parties agreed. Decision 15/9 at COP15 established the principle. Decision 16/2, adopted at Cali on 2 November 2024, operationalised it. The decision creates a #multilateral_mechanism for benefit-sharing from the use of DSI and establishes a global fund, the Cali Fund. Companies in sectors that make commercial use of DSI, such as pharmaceuticals, agricultural biotechnology, cosmetics and certain areas of information technology, are expected to contribute, with indicative rates of one per cent of profits or 0.1 per cent of revenue for entities that exceed size thresholds. Public research is exempt from payment, although it is expected to contribute non-monetary benefits such as data sharing and training. The Fund was launched on 25 February 2025 in Rome, on the margins of the resumed session of COP16, hosted by the Multi-Partner Trust Fund Office in partnership with UNDP and UNEP, with the CBD Secretariat hosting the Fund's own secretariat. At least half of its resources are to be allocated to Indigenous Peoples and local communities, in recognition of their role as custodians of biodiversity. Three things about the Cali Fund deserve emphasis, because they are where the analytical action is. First, contributions are, in practice, voluntary. The decision uses the word "should", and there is no compliance mechanism to compel payment. Whether corporate contributions materialise is therefore an empirical question, and early reporting suggested that uptake was slow. Second, the design deliberately protects open science. This was the price of scientific support, and it distinguishes the DSI mechanism from the bilateral, permit-based logic of Nagoya. Third, the mechanism creates an unresolved interface problem with other regimes, notably the 2023 BBNJ Agreement on marine biodiversity beyond national jurisdiction, which has its own benefit-sharing provisions for marine genetic resources. Making the two systems work together without double payment or double exemption is now an active area of legal scholarship. For students looking for a dissertation topic, this is the single most fertile area in the entire regime. 6. From Aichi to Kunming-Montreal 6.1 The Aichi decade and its failure In 2010, at COP10 in Nagoya, Parties adopted the Strategic Plan for Biodiversity 2011 to 2020, containing twenty #Aichi_Targets. They covered awareness, subsidies, habitat loss, sustainable fisheries, protected areas, extinction prevention, genetic diversity, ecosystem services, restoration, and resources. By the 2020 deadline, not one of the twenty #Aichi_Targets had been fully achieved at the global level. A small number of elements within targets were met. Protected area coverage on land passed 17 per cent, which was the numerical element of Aichi Target 11. The Nagoya Protocol entered into force, satisfying part of Target 16. Most Parties produced an NBSAP, satisfying part of Target 17. But the substantive ecological targets, the ones about halving habitat loss and preventing extinctions and reforming subsidies, were missed comprehensively. Why? The literature converges on five reasons, and they are worth listing because the GBF was designed to address them. Vagueness. Many Aichi Targets combined several distinct commitments in one sentence and used words like "significantly reduced" without saying reduced from what, by how much, or measured how (Maron et al., 2021). No accountability loop. There was no mechanism to compare the sum of national commitments against the global target, and no process to require countries to raise their ambition when the sum fell short. Weak or missing indicators. For several targets there was no agreed way to measure progress at all (Hughes, 2023a). Finance. The resources promised were never delivered at the scale required. Sectoral isolation. Biodiversity policy sat in environment ministries while the drivers of loss sat in agriculture, fisheries, energy, trade and finance ministries. The Convention's own language about #mainstreaming acknowledged the problem without solving it. 6.2 The Kunming-Montreal Global Biodiversity Framework The GBF was adopted by decision 15/4 in Montreal in December 2022, after four years of negotiation, a pandemic delay and a change of venue. Its structure is as follows. A 2050 Vision of "#living_in_harmony_with_nature". Four goals for 2050, covering the integrity of ecosystems and species, the sustainable use and valuation of nature's contributions to people, the fair sharing of benefits from genetic resources and digital sequence information, and the means of implementation. Twenty-three targets for 2030. The targets students most need to know are these. Target 1: all areas under participatory, integrated and biodiversity-inclusive spatial planning. Target 2: at least 30 per cent of degraded terrestrial, inland water, coastal and marine ecosystems under effective #restoration by 2030. Target 3: the famous "#30x30" target. At least 30 per cent of terrestrial, inland water, coastal and marine areas, especially areas of particular importance for biodiversity, effectively conserved and managed through protected areas and #OECMs, recognising Indigenous and traditional territories. Target 6: reduce the rate of introduction and establishment of invasive alien species by at least 50 per cent. Target 7: reduce pollution risks, including by halving excess nutrients and reducing the overall risk from pesticides and highly hazardous chemicals by half. Target 11: restore, maintain and enhance nature's contributions to people. Target 13: ensure fair and equitable sharing of benefits from genetic resources, digital sequence information, and associated traditional knowledge. Target 15: require large and transnational companies and financial institutions to monitor, assess and disclose their risks, dependencies and impacts on biodiversity. Target 18: identify by 2025 and eliminate, phase out or reform incentives harmful to biodiversity, reducing them by at least 500 billion United States dollars per year by 2030. Target 19: mobilise at least 200 billion United States dollars per year from all sources, including at least 20 billion per year in international flows to developing countries by 2025, rising to 30 billion per year by 2030. Target 22: ensure full, equitable, inclusive and effective representation and participation in decision-making by Indigenous Peoples and local communities, women and girls, and youth. Target 23: ensure #gender_equality in implementation. 6.3 What the GBF fixed, and what it did not The improvements are real. The targets are more quantified than the Aichi Targets. There is an agreed monitoring framework with headline, component and complementary indicators, whose full set was finally settled in Rome in 2025 (Affinito et al., 2024; Affinito et al., 2025). There is a planning, monitoring, reporting and review mechanism, which creates a cycle in which national commitments are compared with global targets and a global review is held before each COP. Finance has explicit numbers attached for the first time. Rights language is far stronger, and Target 22 has no real precedent in earlier CBD instruments. The weaknesses are also real, and the literature is blunt about them. The framework is not legally binding in the sense that a Party can be sanctioned for missing a target. The GBF is a COP decision, not a protocol. Several targets are still ambiguous. Bell-James and Watson (2025) show that Targets 2 and 3 each contain multiple distinct elements which most countries simply do not address. The framework retains contradictions with the growth model. It sets a target to reform harmful subsidies but says nothing about the trade rules and financial structures that generate them (Hughes and Grumbine, 2023). There is no burden-sharing formula. The GBF acknowledges different responsibilities and capabilities but never says who pays for what, which is precisely where the distributive justice literature intervenes (Lehmann et al., 2025). And the "30x30" target is vulnerable to a well-known failure mode: the designation of "paper parks", protected areas that exist on maps but not in management. The GBF text tries to close this by requiring that areas be "effectively conserved and managed", but effectiveness is far harder to measure than area, and the data are thin. 7. Implementation: Plans, Indicators and Review 7.1 National Biodiversity Strategies and Action Plans #NBSAPs are the hinge of the whole system. A global target is a statement of intent until it appears in a national plan with a budget attached. Parties were asked to submit revised NBSAPs aligned with the GBF before COP16 in October 2024. The response was poor. Only a small minority of the 196 Parties had submitted a full revised NBSAP by the deadline, although a considerably larger number submitted at least a set of national targets. More important than the number is the quality. Bell-James and Watson (2025) analysed the 36 revised NBSAPs submitted before COP16 and assessed them against the constituent elements of Targets 2 and 3. Their conclusion is stark: no single nation had produced a plan that met all the requirements of these two targets. Countries tended to pick up the headline numbers, 30 per cent protection and 30 per cent restoration, and to ignore the qualifying elements about ecological representativeness, connectivity, equitable governance and recognition of Indigenous and traditional territories. This finding is the most important early empirical result about the GBF, and students should treat it as the central diagnostic fact of the current period. The GBF fixed the design of the global target. It has not yet fixed the translation of that target into national law and budgets. That is the #implementation_gap in its purest form. 7.2 The monitoring framework Under the Aichi regime, monitoring was an afterthought. Under the GBF, it is meant to be structural. The monitoring framework consists of headline indicators, which all Parties are expected to report against, plus binary indicators covering policy responses, plus component and complementary indicators available for optional use. An Ad Hoc Technical Expert Group of 45 nominated experts worked from 2023 to review every indicator, produce methodological guidance, and assess how well the indicator set covers the ambition of the framework (Affinito et al., 2024). Their gap analysis produced an uncomfortable answer. Under the most likely reporting scenario, in which Parties report only on required headline and binary indicators, substantial parts of the GBF's ambition would not be tracked at all (Affinito et al., 2025). Coverage is weakest exactly where the framework is most innovative: on the quality of conservation rather than its extent, on equity and participation, and on the drivers of loss in productive sectors. There is also a capacity problem. Reporting against a sophisticated indicator set requires national biodiversity observation systems, and most countries do not have them. Proposals for a coordinated global biodiversity observing system have been on the table for years (Gonzalez et al., 2023), and the case for standardised approaches, including environmental DNA methods that can be deployed cheaply and consistently, is strengthening. But the infrastructure gap remains large, and it maps almost exactly onto the wealth gap. 7.3 The review cycle COP16 and its resumed session in Rome completed the planning, monitoring, reporting and review mechanism. In outline, it works like this: Parties submit national targets and NBSAPs; Parties submit national reports; the Secretariat aggregates these into a global report on collective progress; the COP conducts a global review; and Parties are expected to respond by strengthening their plans. This is a #ratchet_mechanism, and it borrows openly from the design of the #Paris_Agreement. Its weakness is the same as Paris: nothing forces a Party to ratchet. The mechanism works through transparency, peer pressure and domestic politics rather than through sanction. The first global review will take place at COP17 in Yerevan in October 2026. It will be the first real test of whether the ratchet turns. 8. Finance 8.1 The gap Goal D of the GBF and its associated targets rest on the assumption of a #biodiversity_finance gap of roughly 700 billion United States dollars per year. The figure derives from a comparison between estimated global spending on biodiversity, on the order of 100 to 150 billion dollars annually, and estimated need, on the order of 800 billion. The GBF proposes to close this gap in two ways. Target 18 would eliminate or reform at least 500 billion dollars per year of #harmful_subsidies, chiefly in agriculture, fisheries and fossil fuels. Target 19 would mobilise at least 200 billion dollars per year of positive finance from all sources. Students should treat the 700 billion figure with a degree of caution. It is an estimate built on strong assumptions, and it has been criticised for treating a complex political problem as an accounting shortfall. But even critics accept the direction of the finding: current spending is very far below what the targets imply. 8.2 The channels Finance reaches the ground through several channels. The Global Environment Facility remains the operating entity of the financial mechanism. The #Global_Biodiversity_Framework_Fund, established in 2023 and housed at the GEF, is the dedicated vehicle for GBF implementation. Its capitalisation has been modest relative to the targets, and COP16 explicitly noted the need to scale it up. The Kunming Biodiversity Fund, launched by China and UNEP in 2024 with a commitment of 230 million dollars, supports developing country projects. The Cali Fund is the newest channel, and the only one designed to draw directly on private-sector value derived from biodiversity data. Domestic public finance remains, in aggregate, the largest source of biodiversity spending, and it is systematically underdiscussed in the literature. Private finance, including #biodiversity_credits, green bonds and #debt_for_nature swaps, is growing but small, and it raises questions about whether nature is being turned into a financial asset class. 8.3 The politics The Rome session of COP16 in February 2025 produced agreement on a resource mobilisation strategy. Developing countries had pressed hard for a new dedicated biodiversity fund under the direct authority of the COP, arguing that the GEF is dominated by donors. Developed countries resisted. The compromise defers the question: Parties agreed to work towards improving the effectiveness of the existing financial mechanism, with the possibility of further reform to be considered later. This is the oldest argument in the Convention. It is Article 20 all over again, and it will not go away. Any student writing about CBD finance should read the 2025 Rome decisions alongside the 1992 text and note how little the underlying dispute has moved in thirty-three years. 9. Equity, Rights and Knowledge Systems 9.1 Article 8(j) and its transformation Article 8(j) of the Convention is one sentence, heavily hedged, requiring Parties to respect, preserve and maintain the knowledge, innovations and practices of Indigenous and local communities "subject to national legislation" and to encourage the equitable sharing of benefits from their use. From this narrow base a substantial body of practice has grown. There is now a permanent subsidiary body on Article 8(j), agreed at COP16, and a new programme of work. The GBF's Target 22 requires the effective participation of Indigenous Peoples and local communities in decision-making, and Target 3 explicitly recognises Indigenous and traditional territories as part of the conserved area estate. This last point matters ecologically as well as politically. Protected Planet data indicate that Indigenous and traditional territories cover at least 13.6 per cent of global terrestrial area, and that only a small share of the formally protected estate is governed by Indigenous Peoples and local communities (UNEP-WCMC and IUCN, 2024). Where land is under Indigenous governance, biodiversity outcomes are frequently as good as or better than in state-run protected areas. Recognising this is not sentimentality; it is a conclusion from evidence, and it is also a route to meeting 30x30 without displacing people. The risk is the opposite one. A rush to designate 30 per cent of land and sea can become a driver of #dispossession if it is done without consent. The history of "#fortress_conservation" is not ancient. The GBF's rights language exists precisely to prevent a repeat, and whether it succeeds is one of the key questions for the 2026 to 2030 period. 9.2 Gender Target 23 commits Parties to gender-responsive implementation, and a Gender Plan of Action accompanies the GBF. Development of a renewed Gender Plan of Action is on the agenda for COP17. In practice, gender remains among the least reported and least funded areas of the framework, and the indicator coverage for it is thin. 9.3 Traditional knowledge and the DSI problem There is an unresolved tension at the intersection of Sections 5.3 and 9.1. The Cali Fund allocates at least half of its resources to Indigenous Peoples and local communities. But DSI, by design, is decoupled from the country and community of origin. So how does one identify which community's knowledge or territory contributed to a sequence that was uploaded to a database twenty years ago by a researcher who has since retired? The honest answer is that nobody knows yet, and the modalities are still being negotiated. This is an area where careful, empirically grounded student research could contribute something real. 10. The Convention in the Wider System 10.1 Biodiversity and climate The biodiversity and climate crises are physically coupled. Climate change is now a major driver of biodiversity loss, and ecosystem degradation releases carbon while destroying the systems that absorb it. Conversely, some climate policies harm biodiversity: badly sited bioenergy plantations and monoculture tree-planting schemes can reduce diversity while sequestering carbon (Portner et al., 2023). The governance systems, however, are not coupled. The UNFCCC and the CBD have separate COPs, separate national focal points and separate reporting. Practical alignment, such as ensuring that Nationally Determined Contributions under the Paris Agreement and NBSAPs under the CBD are mutually consistent, is a live agenda item and an obvious research topic. 10.2 Biodiversity and the Sustainable Development Goals The CBD is directly implicated in SDG 14 (life below water) and SDG 15 (life on land), and indirectly in the goals on hunger, health, water, cities and consumption. Biodiversity is best understood as a foundation for the SDGs rather than as one goal among seventeen: without functioning ecosystems, food security and clean water are unattainable. The GBF is therefore best read as a #biodiversity contribution to the 2030 Agenda rather than as a competing framework. Its timeline was deliberately aligned to 2030 for this reason. 10.3 Biodiversity and health The COVID-19 pandemic gave the Convention an unexpected argument. Most emerging infectious diseases are zoonotic, and land-use change, wildlife trade and habitat fragmentation increase the frequency of spillover events. The #One_Health approach, which treats human, animal and ecosystem health as a single system, is now embedded in CBD workstreams and in a global action plan on biodiversity and health. 10.4 The ocean and the BBNJ Agreement The Convention applies to areas within national jurisdiction and, for processes and activities, to areas beyond it. The 2023 Agreement under the United Nations Convention on the Law of the Sea on marine biodiversity of areas beyond national jurisdiction (the #BBNJ or High Seas Treaty) fills the largest remaining gap, providing for marine protected areas on the high seas and for benefit-sharing from marine genetic resources. The high seas cover about 61 per cent of the ocean, and marine protected area coverage there remains very low (UNEP-WCMC and IUCN, 2024). Without BBNJ, the marine component of the 30x30 target is arithmetically implausible. The interaction between BBNJ benefit-sharing and the CBD's DSI mechanism is, as noted above, unsettled. 11. Assessment: Is the Convention Working? Applying the four criteria from Section 3.2 produces a mixed verdict. 11.1 Ambition: high The GBF is, on paper, the most ambitious conservation agenda ever agreed. Protecting 30 per cent of the planet, restoring 30 per cent of degraded ecosystems, halving nutrient pollution and reforming half a trillion dollars of subsidies within a decade would represent a transformation of land use, agriculture and finance (Roberts, 2026). 11.2 Precision: improving but inadequate The targets are more precise than the Aichi Targets, and the indicator set is a genuine advance. But the legal analysis of national plans shows that the targets are still being read selectively, with countries picking the easy numerical element and dropping the qualifying conditions (Bell-James and Watson, 2025). Precision that is achievable only by expert legal reconstruction is not precision that will drive national policy. 11.3 Delegation: weak The Convention delegates very little authority. There is no #compliance_committee with teeth, no dispute settlement in practice, no sanction for failure. The COP operates by consensus. The Secretariat has no enforcement powers. Delegation is limited to information management and facilitation. This is not an oversight; it is the design that made near-universal membership possible. But it means that the treaty's effect depends entirely on domestic politics, and it explains why the same countries that agree ambitious global text go home and do very little. 11.4 Delivery: poor, with pockets of real progress The Protected Planet Report 2024 provides the clearest data. Global coverage of protected and conserved areas stands at 17.6 per cent of terrestrial and inland waters and 8.4 per cent of marine and coastal areas. That represents an increase of less than half a percentage point in each realm since 2020. To reach 30 per cent by 2030 would require an additional 12.4 per cent of land and 21.6 per cent of ocean, meaning that protected areas must nearly double on land and more than triple at sea in the remaining years (UNEP-WCMC and IUCN, 2024). Fifty-one countries and territories already exceed 30 per cent coverage on land, and 31 do so at sea, which shows the target is achievable. But the aggregate trend is nowhere near the required trajectory. On quality, the picture is worse: management effectiveness has been assessed for less than 5 per cent of the world's land within protected areas, and equitable governance assessments have been reported for a vanishingly small fraction of the estate. #Connectivity, which determines whether protected areas function ecologically, is achieved for only about 8.5 per cent of land. Meanwhile, the deadline in Target 18 for identifying harmful subsidies has passed with limited visible action, and the 20 billion dollar international finance milestone for 2025 has not been convincingly met. 11.5 The honest summary The Convention has succeeded in three things. It has established biodiversity as a permanent object of international law and diplomacy. It has built an institutional and normative infrastructure, including two protocols and a benefit-sharing mechanism, that did not exist before. And it has given developing countries and Indigenous Peoples a legal and rhetorical standing they previously lacked. It has failed in one thing, which is the thing it exists for. #Biodiversity is still declining, and the rate of decline has not measurably slowed as a result of the treaty. Both statements are true simultaneously. Students who can hold both in mind at once are thinking about international regimes correctly. 12. Discussion: What Would Make the Difference? 12.1 Mainstreaming is the whole game Every serious analysis reaches the same conclusion: biodiversity policy cannot be delivered by environment ministries. The drivers of loss are agriculture, fisheries, infrastructure, energy, mining and trade. Until biodiversity constraints are built into the decisions taken in those sectors, protected areas will function as islands in a degrading matrix. This is what the Convention means by #mainstreaming, and it is the least glamorous and most important part of the whole agenda. 12.2 Finance must become predictable Voluntary contributions, replenishment cycles and pledges produce volatility, and volatility destroys long-term conservation. Mechanisms that generate predictable revenue, whether from subsidy reform, from levies on commercial use of biodiversity data, or from domestic fiscal policy, are structurally superior to pledges even when the headline sums are smaller. The Cali Fund is an experiment in exactly this, and it deserves close attention. 12.3 Monitoring must be built, not assumed A framework that cannot be measured cannot be reviewed, and a review cycle without measurement is theatre. Investment in national biodiversity observation capacity, including standardised and low-cost methods, is a precondition for the ratchet to function (Gonzalez et al., 2023; Affinito et al., 2025). 12.4 Equity is not a side issue If conservation is experienced as an imposition by rural and Indigenous communities, it will be resisted, and resistance will defeat it. Every piece of evidence about long-term conservation success points to the importance of local rights, local benefit and local governance. The GBF's rights language is therefore not decoration; it is a functional requirement. 12.5 A research agenda for students The following questions are open, tractable and important. Does the planning, monitoring, reporting and review cycle actually raise national ambition between COP17 and COP18? This can be tested empirically by comparing successive NBSAPs. Do corporate contributions to the Cali Fund materialise, and what determines which companies pay? How do the CBD's DSI mechanism and the BBNJ Agreement's marine genetic resource provisions interact in practice? Does the expansion of protected areas under 30x30 correlate with improved biodiversity outcomes, or merely with improved coverage statistics? What happens to subsidy reform under Target 18 when it collides with domestic agricultural politics? How is the new permanent subsidiary body on Article 8(j) changing the balance of influence within the Convention? Each of these can be studied with publicly available documents and data, which makes them realistic topics for a dissertation. 13. Conclusion The Convention on Biological Diversity is a treaty built on a bargain rather than on a command. It cannot order a state to save a forest. What it can do is create a shared language, a shared set of targets, a set of institutions that keep the question alive, and a slow, argumentative process through which national behaviour may eventually shift. Judged against the standard of stopping biodiversity loss, the Convention has not worked. The Aichi Targets were missed entirely, and the early evidence on the Kunming-Montreal Global Biodiversity Framework is not encouraging: protected area coverage is rising far too slowly, national plans are consistently less ambitious than the global targets they are supposed to implement, and finance remains far below what the framework itself says is needed. Judged against the standard of what a consensus-based treaty among 196 sovereign states can plausibly do, the picture is different. The Convention has produced two protocols, a functioning biosafety system, a legal regime for access and benefit-sharing, a monitoring framework, a review cycle, a permanent institutional role for Indigenous Peoples, and, most recently, a mechanism that asks companies profiting from genetic data to pay for the biodiversity that generated it. None of that existed in 1991. The decisive period is now. Between the first global review at COP17 in Yerevan in October 2026 and the 2030 deadline, either national implementation accelerates sharply or the GBF joins the Aichi Targets as a well-drafted failure. The treaty has given the world the architecture. Whether the world builds anything inside it is a political question, and political questions are answered in national capitals, in ministries of finance and agriculture, and in the places where people actually live alongside the biodiversity that the Convention is meant to protect. That is where students of this subject should be looking. Hashtags #Convention_on_Biological_Diversity #CBD_1992 #Global_Biodiversity_Framework #Kunming_Montreal #Nagoya_Protocol #Cartagena_Protocol #Access_and_Benefit_Sharing #Digital_Sequence_Information #CaliFund #Target_30x30 #Biodiversity_Governance #Environmental_Law #Sustainable_Development_Goals #COP16_Cali #COP17_Yerevan References Affinito, F., Williams, J. M., Campbell, J. E., Londono, M. C., and Gonzalez, A. (2024). Progress in developing and operationalizing the Monitoring Framework of the Global Biodiversity Framework. Nature Ecology and Evolution, 8(12), 2163-2171. https://doi.org/10.1038/s41559-024-02566-7 Affinito, F., et al. (2025). Assessing coverage of the monitoring framework of the Kunming-Montreal Global Biodiversity Framework and opportunities to fill gaps. Nature Ecology and Evolution, 9, 1294-1305. Beato, M. S., and Veneroso, V. (2023). The Nagoya Protocol on access and benefit sharing: The neglected issue of animal health. Frontiers in Microbiology, 14, 1124120. https://doi.org/10.3389/fmicb.2023.1124120 Bell-James, J., and Watson, J. E. M. (2025). Ambitions in national plans do not yet match bold international protection and restoration commitments. Nature Ecology and Evolution, 9(3), 417-424. https://doi.org/10.1038/s41559-025-02636-4 Gonzalez, A., et al. (2023). A global biodiversity observing system to unite monitoring and guide action. Nature Ecology and Evolution, 7, 1947-1952. Grumbine, R. E., Xu, J., and Ma, L. (2021). An overview of the problems and prospects for circular agriculture in sustainable food systems in the Anthropocene. Circular Agricultural Systems, 1, 1-11. Gupta, J., Liverman, D., Prodani, K., Aldunce, P., Bai, X., Broadgate, W., et al. (2023). Earth system justice needed to identify and live within Earth system boundaries. Nature Sustainability, 6, 630-638. https://doi.org/10.1038/s41893-023-01064-1 Gurney, G. G., Darling, E. S., Ahmadia, G. N., Agostini, V. N., Ban, N. C., Blythe, J., et al. (2021). Biodiversity needs every tool in the box: use OECMs. Nature, 595, 646-649. Hughes, A. C. (2023a). Developing biodiversity baselines to develop and implement future conservation targets. Plants, 12(12), 2291. https://doi.org/10.3390/plants12122291 Hughes, A. C. (2023b). The post-2020 global biodiversity framework: how did we get here, and where do we go next? Integrative Conservation, 2(1), 1-9. Hughes, A. C., and Grumbine, R. E. (2023). The Kunming-Montreal Global Biodiversity Framework: what it does and does not do, and how to improve it. Frontiers in Environmental Science, 11, 1281536. https://doi.org/10.3389/fenvs.2023.1281536 Hughes, A. C., Auliya, M., Altherr, S., Scheffers, B., Janssen, J., Nijman, V., et al. (2023). Determining the sustainability of legal wildlife trade. Journal of Environmental Management, 341, 117987. Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2022). Methodological Assessment Report on the Diverse Values and Valuation of Nature. IPBES Secretariat, Bonn. Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2023). Thematic Assessment Report on Invasive Alien Species and their Control. IPBES Secretariat, Bonn. Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2024a). Thematic Assessment Report on the Interlinkages among Biodiversity, Water, Food and Health (Nexus Assessment). IPBES Secretariat, Bonn. Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2024b). Thematic Assessment Report on the Underlying Causes of Biodiversity Loss and the Determinants of Transformative Change (Transformative Change Assessment). IPBES Secretariat, Bonn. Lehmann, I., Kok, M., Immerzeel, R., and Marques, A. (2025). Implications of global distributive justice principles for implementation of the Kunming-Montreal Global Biodiversity Framework. Conservation Biology. https://doi.org/10.1111/cobi.70167 Ljungqvist, G. V., Weets, C. M., Stevens, T., et al. (2025). Global patterns in access and benefit-sharing: a comprehensive review of national policies. BMJ Public Health, 3(1), e001800. Maron, M., Simmonds, J. S., Watson, J. E. M., Sonter, L. J., Bennun, L., Griffiths, V. F., et al. (2021). Setting robust biodiversity goals. Conservation Letters, 14(5), e12816. Portner, H.-O., Scholes, R. J., Arneth, A., Barnes, D. K. A., Burrows, M. T., Diamond, S. E., et al. (2023). Overcoming the coupled climate and biodiversity crises and their societal impacts. Science, 380(6642), eabl4881. Roberts, M. (2026). Implementing the Kunming-Montreal Biodiversity Targets. Proceedings of the National Academy of Sciences of the United States of America, 123(2), e2514761123. https://doi.org/10.1073/pnas.2514761123 Scholz, A. H., Freitag, J., Lyal, C. H. C., Sara, R., Cepeda, M. L., Cancio, I., et al. (2022). Multilateral benefit-sharing from digital sequence information will support both science and biodiversity conservation. Nature Communications, 13, 1086. https://doi.org/10.1038/s41467-022-28594-0 Secretariat of the Convention on Biological Diversity (2022). Kunming-Montreal Global Biodiversity Framework. Decision CBD/COP/DEC/15/4. Secretariat of the Convention on Biological Diversity, Montreal. Secretariat of the Convention on Biological Diversity (2022). Digital Sequence Information on Genetic Resources. Decision CBD/COP/DEC/15/9. Secretariat of the Convention on Biological Diversity, Montreal. Secretariat of the Convention on Biological Diversity (2024). Operationalization of the Multilateral Mechanism on Benefit-Sharing from the Use of Digital Sequence Information on Genetic Resources, Including the Cali Fund. Decision CBD/COP/DEC/16/2. Secretariat of the Convention on Biological Diversity, Cali. Secretariat of the Convention on Biological Diversity (2025). Decisions Adopted by the Conference of the Parties to the Convention on Biological Diversity at the Resumed Session of its Sixteenth Meeting. Secretariat of the Convention on Biological Diversity, Rome. United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) and International Union for Conservation of Nature (IUCN) (2024). Protected Planet Report 2024. UNEP-WCMC and IUCN, Cambridge and Gland. Watson, J. E. M., et al. (2023). Priorities for protected area expansion so nations can meet their Kunming-Montreal Global Biodiversity Framework commitments. Integrative Conservation, 2(3), 140-155. World Wide Fund for Nature (WWF) (2024). Living Planet Report 2024: A System in Peril. WWF, Gland.

The Montreal Protocol on Substances that Deplete the Ozone Layer, adopted in 1987, is widely described as the most effective multilateral environmental agreement ever negotiated. This article examines why that description is defensible, what the treaty actually did, and what it can and cannot teach other areas of global policy. Using a structured narrative review of peer reviewed atmospheric science, legal scholarship, and policy analysis published mainly within the last five years, the article traces the Protocol from its scientific origins in the 1970s to its present role in both #ozone_protection and #climate_mitigation. It explains the chemistry of stratospheric ozone loss in accessible terms, reconstructs the negotiation history, and analyses the specific design features that gave the treaty its unusual strength: legally binding and time bound phase out schedules, differentiated deadlines for developing countries, a dedicated funding mechanism, trade restrictions with non parties, and a standing scientific and technical assessment process capable of adjusting controls without reopening the treaty. The article then reviews the measured outcomes. Atmospheric observations confirm that the abundance of controlled chemicals has fallen, that the radiative and chlorine loading from #hydrochlorofluorocarbons began to decline earlier than projected, and that the Antarctic ozone hole now shows a statistically detectable recovery signal attributable to the reduction of controlled substances. The article also examines the failures and unfinished business: illegal production of CFC-11 detected after 2013, rising emissions of unregulated or exempted chemicals, large reservoirs of ozone depleting substances still contained in old equipment and foams, feedstock exemptions, and the new challenges created by the 2016 Kigali Amendment on hydrofluorocarbons. It concludes that the Protocol succeeded because a narrow, tractable problem was matched with a precise, adaptive, and well financed institutional design, and that the transferable lesson for #climate_governance is less about the specific rules than about the relationship between scientific assessment, legal obligation, and industrial capability. Keywords: Montreal Protocol; stratospheric ozone; ozone depleting substances; chlorofluorocarbons; Kigali Amendment; hydrofluorocarbons; multilateral environmental agreements; environmental compliance; atmospheric monitoring; global environmental governance 1. Introduction In the middle of the twentieth century, a family of synthetic chemicals was celebrated as one of the great achievements of industrial chemistry. #Chlorofluorocarbons, usually abbreviated as CFCs, were stable, cheap, non toxic to handle, and non flammable. They made refrigeration affordable, made air conditioning practical in hot climates, made aerosol sprays convenient, cleaned delicate electronic circuit boards, and blew the bubbles into insulating foams. Their greatest commercial virtue was their chemical inertness. They did not react with the contents of a spray can, they did not corrode a compressor, and they did not break down in the lower atmosphere. That same inertness turned out to be the problem. Because CFCs are not destroyed by rain, sunlight, or ordinary chemical reactions near the ground, molecules released in a kitchen in one country drift upward over years and decades until they reach the #stratosphere, the layer of the atmosphere roughly ten to fifty kilometres above the surface. There, intense ultraviolet radiation finally breaks them apart, releasing chlorine atoms into precisely the region of the atmosphere where a thin layer of #ozone absorbs the most biologically damaging part of the solar spectrum. A single chlorine atom, through a catalytic cycle, can destroy many thousands of ozone molecules before it is removed. The chemical property that made CFCs commercially attractive is the same property that allowed them to reach the one place where they could do the most harm. The scientific recognition of this problem, the political response to it, and the industrial transformation that followed together constitute what this article treats as its object of study: the #Montreal_Protocol on Substances that Deplete the Ozone Layer, adopted on 16 September 1987 and in force since 1 January 1989. The Protocol is not simply a statement of concern. It is a specific, binding instrument that names controlled chemicals in annexes, assigns numerical baselines, and sets dated reduction and elimination schedules that parties are legally obliged to meet. It backs those obligations with reporting requirements, a non compliance procedure, trade measures, and a #Multilateral_Fund that pays the agreed incremental costs of compliance in developing countries. The central research question of this article is deceptively simple. Why did this particular treaty work when so many others have not, and how much of that success is transferable? The question matters for students of environmental science, law, economics, and international relations alike, because the Montreal Protocol occupies a peculiar position in public discourse. It is invoked constantly as proof that global cooperation is possible, and yet the details of how it functioned are rarely examined. Slogans about the "world coming together to save the ozone layer" obscure a more interesting and more useful story of scientific uncertainty, industrial resistance, hard bargaining over money, technological substitution, illegal production, and continuous institutional adjustment over nearly four decades. 1.1 Objectives of the article This article pursues five objectives. First, it explains the underlying #atmospheric_science in language that a student without a background in chemistry can follow, while remaining faithful to the current scientific literature. Second, it reconstructs the historical and political path from the first theoretical warnings in 1974, through the discovery of the Antarctic #ozone_hole in 1985, to the adoption of the Protocol in 1987 and its subsequent strengthening. Third, it analyses the treaty as an institutional design problem, identifying the specific mechanisms that generated compliance rather than mere declarations of intent. Fourth, it reviews the measurable environmental, health, and climate outcomes reported in recent peer reviewed assessments, distinguishing between what has been observed, what has been modelled, and what remains projected. Fifth, it examines the Protocol's failures, gaps, and unresolved tensions, including the illegal production episode of the 2010s, the persistence of exempted uses, the enormous #banks of chemicals still locked inside old equipment, and the complications introduced by the switch to #hydrofluorocarbons. 1.2 Why the case still matters It would be reasonable to ask whether an agreement adopted in 1987 is still a live subject. Three considerations suggest that it is. The first is that the job is not finished. The ozone layer has not recovered. Under current projections in the most recent quadrennial assessments, ozone levels are expected to return to their 1980 values around the middle of this century over most of the globe, later over the Arctic, and later still over Antarctica, and only if the phase out schedules continue to be respected. Recovery is a multi decade process because the controlled chemicals persist in the atmosphere for decades after their last release. The second is that the Protocol has been repurposed. Through the 2016 #Kigali_Amendment, an ozone treaty became, in part, a climate treaty, taking on the phase down of hydrofluorocarbons, which do not deplete ozone at all but are extremely powerful #greenhouse_gases. This makes the Protocol a live experiment in whether a successful institution can be extended into a new problem domain. The third is that the Protocol is now the standard reference point in debates about how to design climate agreements. Any serious argument about the architecture of the Paris Agreement, about the merits of binding versus voluntary commitments, or about the role of expert bodies in treaty regimes, sooner or later invokes Montreal. Understanding what the comparison genuinely supports, and where it breaks down, is therefore an essential piece of policy literacy. 1.3 Structure Section 2 sets out the scientific foundations. Section 3 traces the historical and political origins. Section 4 describes the methodology of this review. Section 5 analyses the legal and institutional architecture. Section 6 examines the amendment process and the Kigali Amendment in particular. Section 7 reviews the financial and technology transfer mechanisms. Section 8 addresses compliance, monitoring, and the CFC-11 episode. Section 9 reports on measured outcomes for ozone, ultraviolet radiation, human health, and climate. Section 10 examines remaining problems and criticisms. Section 11 discusses the lessons and their limits for climate governance. Section 12 states the limitations of this study. Section 13 concludes. 2. Scientific Foundations 2.1 What the ozone layer is and what it does Ozone is a molecule made of three oxygen atoms, written as O3. It is chemically distinct from the ordinary oxygen we breathe, which contains two atoms. Ozone is found throughout the atmosphere but is concentrated in the stratosphere, with peak concentrations typically between about fifteen and thirty five kilometres in altitude. Even at its most concentrated, ozone is a trace gas. If all the ozone in a column of the atmosphere above a given point were compressed to sea level pressure, it would form a layer only about three millimetres thick. That thin layer performs a disproportionate function. It absorbs most of the incoming solar #ultraviolet_radiation in the wavelength band known as UV-B, and essentially all of the more energetic UV-C. Without it, the amount of biologically damaging radiation reaching the surface would rise sharply. UV-B damages #DNA in living cells, suppresses aspects of the immune response, causes skin cancers and cataracts in humans, damages the photosynthetic apparatus of plants, and harms the phytoplankton that sit at the base of marine food webs. It is important to distinguish stratospheric ozone from ground level ozone. Near the surface, ozone is an air pollutant and a component of photochemical smog, harmful to lungs and to crops. The same molecule is beneficial high up and harmful low down. This distinction is frequently confused in popular writing and is worth fixing early. 2.2 The natural ozone cycle Ozone in the stratosphere is not a static reservoir. It is continuously created and destroyed. Solar ultraviolet radiation splits ordinary oxygen molecules into single oxygen atoms. Those free atoms combine with intact oxygen molecules to form ozone. Ozone in turn absorbs ultraviolet radiation and breaks apart again, releasing heat, which is why the stratosphere warms with altitude and is stably stratified. This creation and destruction cycle, first described in the early twentieth century, produces a natural steady state concentration. The steady state can be shifted if additional destruction pathways are introduced. Several natural catalytic cycles involving nitrogen, hydrogen, and chlorine compounds already operate. The question raised in the 1970s was whether human activity could add enough catalytic material to shift the balance measurably. The answer was yes. 2.3 The catalytic destruction mechanism In 1974, Mario Molina and Frank Sherwood Rowland published the hypothesis that chlorofluorocarbons, being unreactive in the lower atmosphere, would eventually reach the stratosphere, be photolysed by short wavelength ultraviolet light, and release chlorine atoms that would catalytically destroy ozone. The word #catalytic is doing enormous work in that sentence. A catalyst participates in a reaction and emerges unchanged, ready to participate again. A chlorine atom reacts with an ozone molecule to form chlorine monoxide and ordinary oxygen. The chlorine monoxide then reacts with a free oxygen atom, releasing the chlorine atom once more. The net effect is that ozone is converted to oxygen while the chlorine atom is regenerated and can repeat the cycle. Because of this regeneration, the ratio of damage to input is enormous. Estimates of how many ozone molecules a single chlorine atom can destroy before being sequestered into a reservoir species and eventually removed run into the tens of thousands. Bromine, released from #halons used in fire extinguishing and from methyl bromide used as an agricultural fumigant, is even more destructive per atom, though it is present in much smaller quantities. This is why the treaty controls both chlorine bearing and bromine bearing compounds, and why bromine compounds carry high #ozone_depletion_potential values. 2.4 Ozone depletion potential and global warming potential Two numerical concepts recur throughout the Protocol and the literature around it, and students should be comfortable with both. The first is #Ozone_Depletion_Potential, or ODP. It is a relative index. The reference compound is CFC-11, assigned a value of 1.0. A chemical with an ODP of 0.05 will, per unit mass released, cause about five per cent as much steady state ozone depletion as CFC-11. ODP values depend on the chemical's atmospheric lifetime, the number and type of halogen atoms it carries, and how efficiently those halogens reach the stratosphere. The Protocol's annexes list controlled substances with their ODP values, and the ODP weighted sum of a country's production and consumption is the quantity actually regulated. This is an elegant design choice, because it lets a single scheduled number cover a whole basket of chemicals with different potencies. The second is #Global_Warming_Potential, or GWP, usually quoted over a one hundred year horizon and referenced to carbon dioxide, which is assigned a value of 1. Many of the substances at issue in this story are potent greenhouse gases as well as ozone depleters. CFCs have GWP values in the thousands to tens of thousands. HFCs, which do not deplete ozone, also have GWP values ranging from very low to well over a thousand. The coexistence of these two indices explains why an ozone treaty was eventually able to become a climate instrument. 2.5 The Antarctic ozone hole The theoretical work of the 1970s predicted gradual, globally distributed thinning of a few per cent. What was actually observed in the mid 1980s was far more dramatic and geographically concentrated. British Antarctic Survey scientists reported in 1985 that springtime ozone over Halley Bay in Antarctica had fallen catastrophically, far beyond anything models had anticipated. This became known as the #ozone_hole, though the term is misleading. It is not a hole in the sense of an absence of air, but a seasonal region of severe depletion, at times losing the majority of the ozone column. The explanation required additional chemistry that had not been included in the early models. In the extreme cold of the Antarctic winter stratosphere, inside the isolating vortex of winds that forms over the pole, #polar_stratospheric_clouds condense. On the surfaces of these cloud particles, chlorine compounds that would ordinarily be locked away in relatively harmless reservoir molecules are converted into forms that are easily broken apart by sunlight. When the sun returns in the austral spring, a large stock of reactive chlorine is released all at once into a cold, isolated air mass, and ozone destruction proceeds with extraordinary speed. The result is the deep, sudden, seasonal loss that satellites now image every year. Two features of the Antarctic case are worth underlining for the policy analysis that follows. First, it demonstrated that atmospheric systems can respond non linearly, producing surprises that models did not predict. This is a general argument for precaution. Second, its visual drama, the false colour satellite image of a purple void spreading over a continent, gave the issue a public salience that abstract percentage estimates never could. The image did political work. 2.6 The Arctic and the rest of the world The Arctic does not usually develop a comparable hole, because its stratosphere is warmer and its polar vortex is less stable, so polar stratospheric clouds form less reliably. In unusually cold Arctic winters, however, severe depletion episodes have occurred. Meanwhile, at middle latitudes, where most of the world's population lives, depletion has been more modest in percentage terms but affects far more people. Recent assessments continue to find that, absent the Protocol, sunburning ultraviolet radiation at latitudes below fifty degrees would have risen substantially over recent decades rather than remaining broadly stable. 3. Historical and Political Origins 3.1 From hypothesis to controversy, 1974 to 1985 The Molina and Rowland paper of 1974 did not immediately produce a treaty. It produced an argument. The chemical industry, which had built substantial businesses around CFCs, disputed the significance of the findings, questioned the models, and emphasised the absence of direct observational evidence of depletion. This is an entirely ordinary pattern in the history of environmental regulation and it is important that students see it clearly rather than being taught a sanitised story of instant consensus. Nevertheless, some early action occurred. Several countries, including the United States, Canada, Sweden, and Norway, restricted the use of CFCs in aerosol propellants in the late 1970s, a relatively easy target because substitutes existed and consumers could switch without noticing. This early national action is analytically interesting because it shows that regulation can begin in the sectors where substitution is cheapest, building both technical capability and political confidence for harder sectors later. The 1980s brought an international framework but not yet binding controls. The #Vienna_Convention for the Protection of the Ozone Layer, adopted in 1985, established a general obligation to cooperate on research, monitoring, and information exchange, and created the legal shell within which future protocols could be adopted. It contained no numerical limits on any chemical. A student might reasonably ask what the point of such an agreement is. The answer is that a framework convention lowers the cost of subsequent agreement. It builds the institutional plumbing, the conferences of the parties, the secretariat, and the shared vocabulary, so that when scientific evidence hardens, the negotiation can move to substance immediately rather than starting from nothing. 3.2 The discovery that changed the politics The Antarctic findings published in 1985 arrived just as the Vienna Convention was concluded. The timing was, in retrospect, decisive. An abstract long term risk became a visible, present, and alarming anomaly. Satellite records were re examined and confirmed the ground based observations. Public and governmental attention rose sharply. Even so, causal attribution was not immediately settled. Alternative explanations, including natural dynamical variability and solar cycle effects, were seriously entertained. Field campaigns in the late 1980s, measuring reactive chlorine species directly in the Antarctic stratosphere, produced the decisive evidence linking the depletion to chlorine chemistry. Importantly, the Protocol was signed in 1987 before this attribution work was complete. The treaty was therefore, in the strict sense, an act of #precaution, adopted under real scientific uncertainty about the magnitude and cause of the observed phenomenon. 3.3 The negotiation, 1986 to 1987 The negotiations that produced the Protocol were not harmonious. Positions diverged sharply. The United States, having already banned aerosol uses domestically, favoured strong international controls, partly because its industry had already absorbed the adjustment cost and stood to gain competitively. The European Community, home to major producers, was initially far more cautious and favoured a production capacity cap rather than deep cuts. Developing countries, whose per capita consumption was tiny, were reluctant to accept constraints on technologies that industrialised countries had used freely for decades in building their own refrigeration and cooling infrastructure. Japan raised concerns about solvent uses in electronics. The outcome, adopted in Montreal in September 1987, was a compromise that now looks modest. It required industrialised countries to freeze consumption of the five main CFCs at 1986 levels, then cut them by twenty per cent by 1993 and by fifty per cent by 1998. Halons were to be frozen. Developing countries received a ten year grace period and a low per capita consumption allowance. There was no complete phase out of anything. Judged against the eventual scale of the problem, the original 1987 text was insufficient. Judged as a piece of institutional engineering, it was extraordinary, because it contained within itself the machinery to become sufficient. Three provisions mattered most. The Protocol required periodic scientific, environmental, technical, and economic assessments. It created a procedure by which the parties could tighten controls on already listed substances through #adjustments that bind all parties without requiring each state to complete a fresh ratification. And it established trade restrictions against non parties, which changed the incentives of states considering whether to remain outside. 3.4 The rapid strengthening, 1990 to 1999 Once the assessment machinery began to operate, and once the Antarctic attribution question was resolved, the controls were tightened repeatedly and quickly. The London Amendment of 1990 moved to complete phase out of CFCs and halons for developed countries by 2000 and established the Multilateral Fund. The Copenhagen Amendment of 1992 accelerated those deadlines to 1996 and added #hydrochlorofluorocarbons, methyl bromide, and other substances to the control regime. The Montreal Amendment of 1997 introduced licensing systems for imports and exports of controlled substances, a direct response to emerging illegal trade. The Beijing Amendment of 1999 tightened HCFC controls further and added bromochloromethane. The pattern is important. A treaty that began with a partial fifty per cent cut in a handful of chemicals became, within a decade, a near total prohibition covering almost one hundred substances. This ratchet, driven by assessment panels and executed through adjustments and amendments, is the single most instructive feature of the regime for anyone designing an environmental agreement today. 4. Methodology This article is a structured narrative review rather than an experimental or statistical study. Its purpose is synthesis and explanation, and its method should be stated transparently so that readers can judge its reliability. 4.1 Approach The review proceeded in four stages. First, the scientific basis was established from the most recent peer reviewed assessment literature, principally the quadrennial scientific assessments prepared for the parties to the Protocol and the periodic environmental effects assessments published in the peer reviewed photobiology literature. Second, the observational record of atmospheric abundances and emissions was drawn from primary research articles published in high impact atmospheric science journals, with preference given to work published from 2021 onward. Third, the legal and institutional analysis was constructed from the text of the treaty and its amendments together with policy and governance scholarship. Fourth, the critical and unresolved issues were identified by looking specifically for recent papers reporting anomalies, unexpected emissions, exemptions, and compliance failures, on the principle that a review which reports only successes is not a review. 4.2 Selection criteria Sources were preferred if they satisfied three conditions: publication in a peer reviewed venue or in an official assessment prepared by an expert panel under an intergovernmental process; publication within approximately the last five years, so that the evidence reflects the current state of the ozone layer rather than its condition a decade ago; and direct relevance to one of the article's five objectives. Older foundational work is referred to descriptively in the text where it is historically necessary, for example the original catalytic hypothesis and the discovery of the Antarctic depletion, but the analytical claims rest on recent literature. 4.3 Limitations of the method A narrative review cannot claim the systematic completeness of a formal meta analysis, and it is vulnerable to selection effects introduced by the author's judgement about what counts as important. The topic also spans several disciplines whose standards of evidence differ. Atmospheric chemistry offers precise measurement with quantified uncertainty. Political science and law offer interpretation and contested causal narratives. A claim that stratospheric chlorine loading has declined by a specified amount is of a different epistemic character from a claim that trade restrictions caused universal ratification. This article attempts to signal that difference wherever it arises rather than presenting all claims with equal confidence. 5. The Institutional Architecture of the Protocol The heart of this article's argument is that the Protocol's effectiveness is a product of design, not of goodwill. This section identifies the design features that did the work. 5.1 Specific, binding, dated obligations The Protocol does not ask parties to make best efforts. It specifies chemicals by name in its annexes, defines a #baseline year for each group, and requires that production and consumption fall to defined percentages of that baseline by defined dates, ending at zero. #Consumption is defined in a way that closes an obvious loophole: it is production plus imports minus exports, so that a country cannot claim compliance by shutting its factories and importing everything instead. This precision produces two benefits. It makes compliance auditable. A party either reported production below the ceiling or it did not. And it makes obligations legible to industry. A chemical company that knows a substance will be prohibited on a specific date can plan capital investment, retool plants, and develop substitutes with confidence that its competitors face the same deadline. Vague obligations produce paralysis, because the first mover bears the cost of adjustment while free riders capture the benefit. Dated prohibitions convert a #collective_action_problem into an engineering schedule. 5.2 Common but differentiated responsibility in operational form Article 5 of the Protocol defines a category of developing country parties with low per capita consumption and grants them a delayed compliance schedule. This is one of the earliest operational expressions of the principle of #common_but_differentiated_responsibilities in international environmental law, and it is far more concrete than the versions later written into climate agreements. The design solved a real fairness problem and a real participation problem simultaneously. Industrialised countries had built their prosperity partly on unrestricted use of these chemicals. Requiring countries at an earlier stage of development to abandon affordable refrigeration on the same timetable, without assistance, would have been both inequitable and politically impossible. The grace period, combined with financial assistance, converted potential opponents into participants. The Protocol is today universally ratified, which is not an accident but the outcome of this bargain. 5.3 Trade restrictions and the problem of leakage Article 4 restricts trade in controlled substances between parties and non parties. This provision addressed the risk that production would simply migrate to countries outside the agreement, undermining the environmental objective and penalising the industries of complying states. By making non participation commercially costly, the trade measures altered the calculus of joining. For a state weighing the cost of compliance against the cost of exclusion from markets in refrigerants, cooling equipment, and related goods, the balance tipped toward accession. Trade measures in environmental treaties remain legally and politically contentious, particularly in relation to world trade rules. The Montreal case is nevertheless the standard example of such measures functioning as intended, and it is regularly cited in current debates about carbon border adjustment mechanisms. 5.4 The assessment panels The Protocol institutionalised expertise. Three standing panels report to the parties: a Scientific Assessment Panel on the state of the ozone layer and the atmosphere, an Environmental Effects Assessment Panel on the consequences of ultraviolet radiation for health and ecosystems, and a Technology and Economic Assessment Panel on the availability, cost, and performance of alternatives. Their assessments are produced on a regular cycle and are the formal basis on which parties decide whether to tighten controls. The significance of the third panel deserves emphasis, because it is often overlooked. Scientific evidence of harm tells governments that they should act. Technical evidence of feasible substitutes tells them that they can. Negotiators who possess a credible, expert, and jointly produced statement that a substitute exists, works, and costs a given amount are in a fundamentally different bargaining position from negotiators who must rely on the claims of the affected industry. The #TEAP therefore functioned as a solvent for the standard industrial objection that regulation is technically impossible. 5.5 Adjustments: legislating without renegotiating Perhaps the most quietly brilliant feature of the Protocol is the distinction between amendments and adjustments. An #amendment adds new substances or new types of obligation and must be ratified by each party according to its own constitutional process, which is slow. An adjustment tightens the schedule for a substance already listed, and, once agreed by the parties according to specified voting rules, becomes binding on all parties without individual ratification. This mechanism gave the regime the capacity to accelerate. When the science indicated that a fifty per cent cut was inadequate, the parties did not need to negotiate an entirely new treaty and wait years for parliaments to ratify it. They adjusted. The result is a legal instrument that can respond to evidence at something closer to the speed at which evidence accumulates, which is a rare and valuable property in international law. 5.6 Reporting, review, and the non compliance procedure Parties must report annual data on production, consumption, imports, and exports of controlled substances. An Implementation Committee reviews possible cases of non compliance. Its orientation is deliberately facilitative rather than punitive. A party found to be out of compliance is typically offered technical and financial assistance, given a plan of action with benchmarks, and monitored. Sanctions, including suspension of rights and privileges under the treaty, exist but are held in reserve. This design reflects an important insight. Most non compliance in this regime has stemmed from incapacity rather than from deliberate defiance: weak customs enforcement, poor data systems, absence of trained technicians, or the collapse of state administrative structures. A regime that responded to incapacity with punishment would generate concealment. A regime that responds with assistance generates disclosure. The facilitative model has limits, and it is fair to ask whether it was adequate to the illegal production episode discussed below, but as a general architecture it has been vindicated. 6. The Amendment Process and the Kigali Turn 6.1 The substitution chain The history of the Protocol can be told as a chain of chemical substitutions, each solving one problem and creating another. Understanding this chain is essential, because it explains both the treaty's continuing relevance and the criticism most often directed at it. The first substitutes for CFCs were hydrochlorofluorocarbons. HCFCs contain hydrogen, which makes them vulnerable to attack by hydroxyl radicals in the lower atmosphere. Most HCFC molecules are therefore destroyed before they reach the stratosphere. Their ODP values are far lower than those of CFCs, typically in the range of a few per cent of CFC-11. They were explicitly conceived as #transitional_substances: better, but not good, and destined for eventual elimination. The second wave of substitutes were hydrofluorocarbons. HFCs contain no chlorine or bromine at all. Their ODP is effectively zero. From the standpoint of the ozone layer they are a complete solution. From the standpoint of the climate system they are, in many cases, a serious problem, because a number of the commercially dominant HFCs are greenhouse gases with global warming potentials in the hundreds or thousands, and their use was growing rapidly with the global expansion of #refrigeration and #air_conditioning, particularly in hot and rapidly developing regions. This is a textbook case of what policy analysts call a #regrettable_substitution, or more charitably a problem shifting outcome. The ozone regime solved its own problem by exporting part of it to the climate regime. Recent projection studies, based on observed atmospheric abundances rather than on inventories alone, indicated that unregulated growth in HFC use could have contributed several tenths of a degree of additional global surface warming by 2100 (Velders et al., 2022). That is a very large number for a single family of industrial chemicals. 6.2 The Kigali Amendment The response was the Kigali Amendment, agreed in October 2016 and in force since 1 January 2019. It brought HFCs, which do not deplete ozone, under the control of an ozone treaty, on the reasoning that the Protocol had created the HFC problem, possessed the institutional machinery and the industry relationships to solve it, and could act faster than the climate regime. The Amendment establishes a #phase_down rather than a phase out. Parties are required to reduce production and consumption of HFCs, measured in carbon dioxide equivalent terms using global warming potentials rather than ODP, along staged schedules. Developed countries began reducing first, from 2019. Developing country groups follow later, with two distinct schedules reflecting different baselines and circumstances, and with the highest ambient temperature countries, where cooling loads are extreme and low GWP alternatives are technically harder to deploy, given additional time. The design deliberately reuses the architecture that worked for ozone: legally binding numerical schedules, differentiated timetables, licensing and reporting, expert assessment, and financing through the Multilateral Fund. The estimated climate benefit if the schedules are met in full is substantial. Analyses reported in the assessment literature indicate that full compliance would avoid several gigatonnes of carbon dioxide equivalent emissions annually by mid century and would reduce the eventual warming contribution of HFCs from a range of roughly a few tenths of a degree to a small fraction of that by 2100 (Velders et al., 2022). 6.3 Energy efficiency as a hidden dividend An underappreciated aspect of the Kigali transition is that replacing a refrigerant usually means redesigning the equipment around it. When equipment is redesigned, the opportunity exists to improve its #energy_efficiency at the same time, which reduces electricity demand and therefore reduces emissions from power generation. Analysts have consistently argued that the indirect climate benefit available from coupling refrigerant transition with efficiency improvement may be comparable to, or larger than, the direct benefit of the refrigerant change itself. This matters for developing economies, where the number of air conditioners in use is expanding very rapidly and where the efficiency of the installed stock is often poor. It also illustrates a general point about environmental policy: the greatest gains often lie not in the substance being regulated but in the system that is opened for redesign when regulation forces the substitution. 6.4 The trade offs of the new substitutes The chemicals now replacing high GWP HFCs include hydrofluoroolefins, natural refrigerants such as ammonia, carbon dioxide, and hydrocarbons, and various blends. Each carries its own profile of costs. Hydrocarbons are flammable, which constrains charge sizes and requires revised safety standards and trained technicians. Ammonia is toxic. Carbon dioxide systems operate at high pressure. Hydrofluoroolefins have very short atmospheric lifetimes and low GWP, but their atmospheric breakdown can yield #trifluoroacetic_acid, a persistent compound that accumulates in water bodies and whose long term environmental consequences remain a subject of active research and legitimate scientific debate. The honest conclusion is that no substitution in this field has been free of consequence, and that the assessment of new substitutes must be continuous rather than a single approval decision. This is an argument for maintaining the assessment panels indefinitely, not for abandoning substitution. 7. Financing and Technology Transfer 7.1 The Multilateral Fund The Multilateral Fund for the Implementation of the Montreal Protocol, established in 1990, is the mechanism that made universal participation possible. Its operating principle is that developed country parties pay the agreed #incremental_costs incurred by developing country parties in meeting their control obligations. Incremental cost means the additional cost of doing the thing in the compliant way rather than the cheapest way, including plant conversion, technology licensing, technician training, and the institutional strengthening needed to run a licensing system. The Fund is replenished on a multi year cycle, is governed by an Executive Committee with balanced representation between contributing and recipient countries, and delivers projects through implementing agencies. Over more than three decades it has financed thousands of projects across the great majority of developing country parties. Three features of the Fund merit analytical attention. The first is that its existence converted the phase out from an imposition into a bargain. Developing countries did not simply accept obligations; they accepted obligations in exchange for a legally linked commitment of financing. The Protocol makes this explicit: developing country compliance is conditioned on the effective implementation of financial cooperation. The second is that the Fund financed capability, not merely equipment. Training refrigeration technicians, establishing customs enforcement capacity, setting up national ozone units inside environment ministries: these unglamorous investments built the administrative machinery on which reporting and enforcement depend. A treaty obligation without an agency capable of executing it is a piece of paper. The third is that the sums involved, while large in absolute terms, were modest compared with the scale of the industries transformed and trivial compared with the estimated damages avoided. The economics of ozone protection were, in the end, extraordinarily favourable. This is not a general truth about environmental problems, and the point is developed further in Section 11. 7.2 Technology transfer and its frictions Technology transfer under the Protocol was not friction free. Substitute technologies were frequently protected by patents held by firms in industrialised countries. Recipient countries argued that intellectual property costs inflated the price of compliance and that access to the best available technology was not always granted on reasonable terms. Disputes over what counted as an eligible incremental cost recurred throughout the Fund's history. These frictions are worth studying precisely because they are the friction points that reappear in every subsequent negotiation about climate technology. The Montreal experience suggests that a dedicated fund with a mandate to pay agreed incremental costs, governed jointly, is workable, but that it does not dissolve the underlying tension between the diffusion of technology and the protection of the commercial returns that finance its development. 8. Compliance, Monitoring, and the CFC-11 Episode 8.1 Two kinds of verification The Protocol is verified twice, by two independent systems. The first is administrative. Parties report their production, import, and export data to the secretariat. These reports are the legal basis for compliance assessment. They are also, in principle, falsifiable by a party willing to lie. The second is atmospheric. Global networks of monitoring stations, operated by national laboratories and international research consortia, measure the actual concentrations of controlled substances in air samples collected at remote sites around the world. From these measurements, and with the aid of atmospheric transport models, scientists derive independent estimates of global and, increasingly, regional emissions. The relationship between these two systems is the most important compliance story in the history of the treaty. When reported production says one thing and the atmosphere says another, the atmosphere is right. 8.2 The CFC-11 anomaly The production of CFC-11 for emissive uses was banned globally under the Protocol, with a final phase out for developing countries completed in 2010. Its atmospheric concentration should therefore have declined steadily and predictably as the existing stock decayed. From around 2013, the observed rate of decline slowed. The only plausible explanation was new emissions, and the most plausible source of new emissions was new production, which would mean a violation of the treaty. Subsequent regional analyses, using high frequency measurements at monitoring stations in East Asia together with transport modelling, attributed a substantial part of the increase to eastern China, most likely associated with the manufacture of insulating foams. The episode is significant for several reasons. It demonstrated that a treaty obligation can be violated on an industrially meaningful scale without any government necessarily intending it, because the actual actors were enterprises, not states. It demonstrated that independent atmospheric monitoring is not a scientific luxury but a core compliance instrument. And it demonstrated that the regime's response mechanisms could work. Follow up studies published in 2021 reported that global CFC-11 emissions declined sharply after 2018, with the global figure for 2019 returning to a level comparable to the 2008 to 2012 mean, and that emissions from eastern China had likewise returned to pre 2013 levels (Montzka et al., 2021; Park et al., 2021). The scientific detection, the public exposure, the diplomatic pressure, and the enforcement response together produced a correction within a few years. The estimated delay to ozone layer recovery caused by the episode was therefore limited, though not zero. 8.3 The lessons of the anomaly Three lessons follow. First, #atmospheric_monitoring must be sustained and expanded. The regional attribution that made the CFC-11 case actionable was possible only because monitoring stations existed in the right places. Large regions of the world, particularly in Africa, South Asia, and South America, remain sparsely instrumented, which means that unreported emissions from those regions would be far harder to localise. The current literature repeatedly flags the risk of gaps in the observing system, including gaps in satellite measurements of the stratosphere. Second, enforcement is domestic. The Protocol can create obligations for states, but the actual prevention of illegal production requires national inspectors, functioning customs services, criminal penalties, and the political will to apply them to profitable local enterprises. Third, illegal trade is a chronic feature, not an aberration. Black markets in controlled refrigerants have existed since the 1990s, driven by the price gap between prohibited and permitted substances and by the long service life of equipment that still runs on the old chemicals. The licensing system introduced in 1997 was a direct response, and enforcement effort must be assumed to be permanently necessary. 9. Measured Outcomes This section separates what has been measured from what has been projected. The distinction is not pedantic. The credibility of the entire ozone regime rests on the fact that its central claims are observationally testable, and have been tested. 9.1 The atmospheric burden of controlled substances The total quantity of ozone depleting chlorine and bromine in the atmosphere peaked in the 1990s and has been declining since. This is not a model output. It is a measurement, made by multiple independent global networks using different instruments and different calibration standards, and the networks agree. A particularly clear recent result concerns HCFCs, the transitional substances. Analysis of observed abundances found that the radiative forcing and the equivalent effective chlorine attributable to HCFCs both began to decline from 2021, approximately five years earlier than the most recent projections had anticipated (Western et al., 2024). Being ahead of schedule is an unusual position for an environmental treaty to occupy and it deserves to be stated plainly. 9.2 The recovery of stratospheric ozone Detecting recovery of the ozone layer itself is scientifically harder than detecting the decline of the chemicals, because ozone concentrations vary enormously from year to year for reasons that have nothing to do with chlorine: winds, temperature, volcanic aerosol, the solar cycle, and the internal variability of the stratosphere. Distinguishing a slow forced trend from a noisy background requires long records and careful statistics, and premature claims of recovery would have been scientifically irresponsible. A study published in 2025 applied formal #fingerprinting methods, of the kind developed in climate change detection and attribution research, to satellite observations of Antarctic ozone combined with model ensembles. It identified a pattern of ozone increase as a function of month and altitude that matches the expected signature of declining ozone depleting substances, and reported that this signal can be detected with high statistical confidence and separated from internal variability (Wang et al., 2025). This is the strongest formal evidence to date that the Antarctic ozone hole is healing and that the healing is attributable to the Protocol rather than to chance. The projected timeline for full recovery, as summarised in the current assessment literature, is that ozone will return to 1980 levels around 2066 over Antarctica, around 2045 over the Arctic, and around 2040 for the rest of the world, conditional on continued compliance. These dates are projections and they will move as the observational record grows. 9.3 Ultraviolet radiation and human health Because ozone controls the transmission of UV-B, the ozone trend translates into a #surface_UV trend. Assessments of the ultraviolet record find that at low and middle latitudes, changes in sunburning ultraviolet radiation over recent decades have been modest and driven substantially by clouds and aerosols rather than ozone, and that in the absence of the Protocol, erythemal ultraviolet irradiance at latitudes below fifty degrees would have risen by something on the order of ten to twenty per cent over the period from the mid 1990s to 2020 (Bernhard et al., 2023). The health consequences avoided are correspondingly large. Higher UV-B exposure increases the incidence of #skin_cancer, including melanoma and the more common keratinocyte cancers, increases the risk of cortical #cataract, which is a leading cause of blindness worldwide, and suppresses aspects of local and systemic immunity. Estimates of avoided cases run into the many millions over the coming century, though such figures are necessarily model based and depend on assumptions about behaviour, demography, and skin type distribution. It is worth adding a note of scientific balance that the assessment literature itself insists upon. Ultraviolet radiation is not purely harmful. It drives cutaneous synthesis of #vitamin_D and has other physiological effects. Public health messaging that treats sunlight as uniformly dangerous is not supported by the evidence, and the assessment panels have consistently framed the issue in terms of appropriate exposure rather than avoidance. 9.4 Ecosystems and biogeochemistry Elevated UV-B affects terrestrial plants, reducing growth in sensitive species, altering leaf chemistry, and changing the balance of competition within plant communities. In aquatic systems it penetrates the upper layers of clear water and damages phytoplankton, the organisms that fix carbon at the base of the marine food web and that are responsible for a large share of global primary production. It also alters the photochemical degradation of dissolved organic matter, with consequences for carbon and nutrient cycling. A striking result in the recent literature concerns the #terrestrial_carbon_sink. Modelling work published in 2021 examined a counterfactual world in which CFCs had continued to grow through the twenty first century. In that world, severe global ozone depletion would have driven ultraviolet radiation to levels that substantially suppressed plant growth and therefore reduced the amount of carbon that vegetation removes from the atmosphere. The reduced land carbon sink, combined with the direct greenhouse effect of the CFCs themselves, would have produced very large additional warming by 2100 (Young et al., 2021). The Protocol, in other words, protected the climate system through at least three distinct pathways: by preventing the direct radiative forcing of CFCs, by preventing the loss of the land carbon sink, and later, through Kigali, by constraining HFCs. 9.5 The climate co-benefit Because CFCs and many of their relatives are potent greenhouse gases, their elimination removed a growing source of radiative forcing. Multiple analyses have concluded that the greenhouse gas mitigation achieved incidentally by the Montreal Protocol, measured in carbon dioxide equivalent terms, exceeds the mitigation achieved deliberately by the Kyoto Protocol. The Montreal Protocol is, on this accounting, the most successful climate agreement ever adopted, and it was not designed as one. There is also a documented influence of ozone depletion on atmospheric circulation, particularly in the Southern Hemisphere, where the ozone hole has been linked to a poleward shift in the mid latitude jet and associated changes in wind and precipitation patterns. Ozone recovery is expected to partly reverse these shifts, which means that the Protocol has consequences for regional climate that extend beyond the direct radiative accounting. 9.6 Economic effects The transition was not costless, but it was far cheaper than industry initially predicted. This is a recurring finding in environmental regulation and it is worth stating explicitly for students who will encounter cost estimates in future debates. Ex ante compliance cost estimates produced by regulated industries have, in a wide range of cases, exceeded realised costs, because such estimates are typically made on the assumption that innovation will not occur, whereas the imposition of a binding deadline is itself a powerful stimulus to innovation. The refrigeration, air conditioning, foam, solvent, aerosol, and fire protection industries were all reengineered. Many firms that invested early in substitutes gained commercially. Comparisons of the cost of compliance with the value of avoided health damage and avoided agricultural loss have consistently found benefit to cost ratios that are very large. 10. Remaining Problems and Legitimate Criticisms An article that stopped at Section 9 would be a celebration rather than an analysis. The following problems are all documented in the recent literature and all remain open. 10.1 Banks The #banks are the stocks of ozone depleting substances that still exist inside old refrigerators, chillers, air conditioners, foam insulation panels in buildings, and fire suppression systems. These chemicals have already been produced. They are not currently in the atmosphere. They will reach the atmosphere unless the equipment is captured and the contents destroyed at end of life. The quantities are large enough to matter for the timing of ozone recovery and for the climate. Recovering and destroying banked substances is technically feasible but economically unattractive, because it costs money and produces no salable product. The Protocol has never established a strong obligation to manage banks, and this is arguably its most significant regulatory gap. Recent policy analysis identifies bank management as one of the largest remaining opportunities for additional climate and ozone benefit available under the existing institution. 10.2 Feedstock exemptions The Protocol exempts substances produced for use as #feedstocks, meaning chemicals consumed as raw material in the manufacture of other chemicals rather than released into the environment. The exemption rested on the assumption that feedstock use is essentially emission free. That assumption has proved incorrect. Feedstock production has grown rather than declined, and measured emission rates from feedstock processes are substantially higher than the small fraction originally assumed. Analysts have argued that narrowing feedstock exemptions through the Protocol's adjustment procedure would deliver ozone benefits, climate benefits, and, because many of the relevant feedstocks are inputs to plastics manufacture, benefits for #plastic_pollution as well (Andersen et al., 2021). 10.3 Unexpected and unregulated emissions Measurements have revealed rising atmospheric abundances of several CFCs whose emissive production is banned. Analysis of five such compounds found that their concentrations and emissions increased between 2010 and 2020, most plausibly as unintended by products of the manufacture of other chemicals, including HFCs, rather than as a result of prohibited emissive use (Western et al., 2023). The current impact on the ozone layer is small. The finding nevertheless illustrates a structural feature of chemical regulation: prohibiting a use does not prohibit a molecule, and molecules can re enter the atmosphere through pathways the regulation did not anticipate. A related issue concerns #very_short_lived_substances, chlorinated compounds such as dichloromethane which have atmospheric lifetimes of only months and were therefore never controlled, on the assumption that they could not reach the stratosphere in significant quantities. Rising industrial use, combined with rapid transport pathways in the tropics, means that a non negligible quantity does reach the stratosphere, and this is now an active area of assessment. 10.4 HFC-23 and the perverse incentive problem HFC-23 is an extremely potent greenhouse gas generated as an unwanted by product in the manufacture of HCFC-22. It can be destroyed cheaply by incineration. Under an earlier carbon market mechanism, plants could earn credits for destroying it, which created a documented perverse incentive to produce more HCFC-22 than the market required in order to generate more by product to destroy for credit. The Kigali Amendment addresses HFC-23 directly by requiring its destruction to the extent practicable, but atmospheric measurements have at times indicated emissions higher than reported destruction rates would imply. The episode is a permanent teaching case about the interaction between environmental regulation and financial incentives. 10.5 The critique of institutional persistence A provocative argument has appeared in the recent literature suggesting that some environmental conventions outlive their usefulness and should be wound up, and that the Montreal Protocol might eventually be a candidate for absorption of its residual functions into the climate regime. The counter argument, defended vigorously by ozone specialists, is that the Protocol's work is manifestly unfinished: the layer has not recovered, banks remain unmanaged, feedstocks remain exempt, illegal production remains possible, the Kigali phase down has barely begun, and the monitoring infrastructure that made all of this visible depends on the institution's continued existence. This debate is worth following, because it raises the general question of how international institutions should end, a question that international law addresses very poorly. 10.6 Equity and the burden of the transition Finally, an equity critique deserves a hearing. The countries that consumed the most CFCs per capita during the period of unrestricted use were the industrialised countries. The countries now being asked to leapfrog to more expensive low GWP cooling technologies, often in the hottest climates and with the least ability to pay, are largely developing countries. The Multilateral Fund exists precisely to address this, and it works better than most such mechanisms. Whether it is adequately funded relative to the scale of the cooling transition now under way, particularly as air conditioning demand grows in South Asia, the Middle East, Africa, and Southeast Asia, is a legitimate and open question. 11. What the Montreal Protocol Can and Cannot Teach Climate Policy The comparison between Montreal and the climate regime is made so often, and so loosely, that it is worth doing carefully. 11.1 The transferable lessons Several features of the Montreal design appear genuinely transferable. Binding, dated, specific targets are more effective than aspirational ones, because they let industry plan and let compliance be measured. Independent physical verification is indispensable, because self reported data can be wrong and, occasionally, false. Expert assessment of technological feasibility, produced jointly and credibly, disarms the standard objection that regulation is impossible. Financial mechanisms that pay the incremental costs of compliance in poorer countries convert opponents into participants. Legal mechanisms that permit tightening without full renegotiation allow a treaty to track the science. Facilitative compliance procedures generate disclosure. Trade measures reduce leakage. And starting where substitution is cheapest builds capability and confidence for the harder sectors. These are not platitudes; they are specific institutional choices, and the climate regime has adopted some of them and not others. 11.2 The disanalogies The differences, however, are profound, and any student who repeats the "if we could do it for ozone we can do it for carbon" line without qualification should be able to state them. The number of relevant chemicals in the ozone case was small, and the number of producers smaller still. Global production was concentrated in a modest number of firms in a modest number of countries. Carbon dioxide is emitted by every combustion process on the planet, by billions of actors. The economic centrality of the substances differed by orders of magnitude. CFCs were a valuable but ultimately peripheral input to the world economy. Fossil energy is the substrate of industrial civilisation. Replacing a refrigerant is an engineering problem. Replacing the energy system is a civilisational one. Substitutes existed, or could be developed quickly, and their cost premium was small. That is the single most important disanalogy. Regulation succeeds when a technically feasible alternative exists, and struggles when it does not. The affected industry, having initially resisted, eventually calculated that it could profit from the transition, because patented substitutes are more valuable than commodity chemicals whose patents have long expired. This alignment of commercial and regulatory interest was fortuitous and is not reliably reproducible. The harms were vivid, near term, and personally threatening. Skin cancer and blindness are concrete in a way that a two degree temperature rise is not, and the ozone hole provided an image that no climate dataset has ever matched for public communicability. Finally, the counterfactual was terrifying and, once the models improved, unambiguous. The literature on the "world avoided" describes a scenario of catastrophic global ozone collapse by mid century. Faced with that, the cost of substitution looked trivial. 11.3 A more careful reading The correct lesson, then, is not that binding treaties always work. It is that binding treaties work when they are matched to the structure of the problem. The Montreal Protocol succeeded because a tractable technical problem with a concentrated industry, a vivid harm, an available substitute, and a credible scientific consensus was met with an institution designed to exploit exactly those features: precise obligations, adaptive tightening, expert assessment, targeted financing, and independent verification. Where climate policy has borrowed the architecture without the underlying conditions, the results have been disappointing. Where it has borrowed selectively and intelligently, for example in the Kigali Amendment itself, which addresses a concentrated industry with available substitutes, the results have been encouraging. The Kigali Amendment is arguably the best available test of the transferability thesis, precisely because it applies the Montreal machinery to a climate pollutant, and its progress over the next two decades should be watched closely by anyone interested in this question. 12. Limitations of This Study Several limitations qualify the conclusions offered here. This is a review, not primary research. It reports the findings of others and its reliability is bounded by theirs. The literature on the political history of the Protocol is dominated by accounts written by participants and by scholars sympathetic to the regime. Accounts written from the perspective of the firms and governments that resisted are comparatively scarce, and this may introduce a bias toward heroic narrative that the present article has tried, but may not have entirely managed, to resist. Quantitative claims about avoided health damage and avoided warming rest on counterfactual modelling, and counterfactuals cannot be observed. They should be treated as well founded estimates with substantial uncertainty rather than as measurements. The article does not attempt a detailed technical evaluation of individual substitute chemicals, which would require chemical engineering expertise beyond its scope. Finally, the Kigali Amendment is recent, and its implementation is at an early stage. Any judgement of its success offered today is provisional. 13. Conclusion The Montreal Protocol deserves its reputation, but not for the reason it is usually given. It is not proof that the world unites when the danger is great enough. The world was not united in 1987. Governments disagreed, industry resisted, the science was incomplete, and the first agreement was too weak to solve the problem. What the Protocol proves is something more useful and more demanding. It proves that an international institution can be built with the capacity to learn. The 1987 treaty was inadequate, but it was designed so that inadequacy could be corrected: it required assessment, it permitted adjustment without renegotiation, it created a fund so that poorer countries could join the bargain rather than defect from it, it made compliance measurable, and it was accompanied, though not by design, by an independent scientific monitoring system capable of catching a violation that no government reported. The results are visible in the atmosphere. The burden of ozone depleting chemicals has fallen. The forcing from transitional substances began declining ahead of schedule. The Antarctic ozone hole now carries a statistically detectable fingerprint of recovery attributable to human action. Millions of cases of skin cancer and cataract will not occur. A very large quantity of greenhouse warming has been avoided, both directly and by protecting the capacity of the land biosphere to absorb carbon. The work is not finished. Banks remain unmanaged, feedstock exemptions remain open, unregulated compounds are rising, illegal production remains possible, and the HFC phase down has barely started. The Protocol will need to remain in operation, and its assessment and monitoring infrastructure will need to remain funded, for decades after the last person who remembers the discovery of the ozone hole has retired. For students of environmental policy, the enduring lesson is about fit. Institutions succeed when their design matches the structure of the problem they address. The task is not to copy the Montreal Protocol but to understand why it worked, and to ask, of every new environmental problem, what combination of scientific credibility, legal precision, technological feasibility, financial fairness, and independent verification that particular problem requires. Hashtags #Montreal_Protocol #Ozone_Layer #Ozone_Depletion #Ozone_Depleting_Substances #CFCs #HCFCs #HFCs #Kigali_Amendment #Vienna_Convention #Multilateral_Fund #Stratospheric_Ozone #Environmental_Governance #Climate_Policy #Environmental_Law #Sustainability References Andersen, S. O., Gao, S., Carvalho, S., Ferris, T., Gonzalez, M., Sherman, N. J., Wei, Y., and Zaelke, D. (2021). Narrowing feedstock exemptions under the Montreal Protocol has multiple environmental benefits. Proceedings of the National Academy of Sciences, 118(49), e2022668118. https://doi.org/10.1073/pnas.2022668118 Barnes, P. W., Robson, T. M., Neale, P. J., Williamson, C. E., Zepp, R. G., Madronich, S., Wilson, S. R., Andrady, A. L., Heikkila, A. M., Bernhard, G. H., and colleagues (2022). Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2021. Photochemical and Photobiological Sciences, 21, 275 to 301. https://doi.org/10.1007/s43630-022-00176-5 Bernhard, G. H., Bais, A. F., Aucamp, P. J., Klekociuk, A. R., Liley, J. B., and McKenzie, R. L. (2023). Stratospheric ozone, UV radiation, and climate interactions. Photochemical and Photobiological Sciences, 22. https://doi.org/10.1007/s43630-023-00371-y Bernhard, G. H., Neale, R. E., Neale, P. J., and colleagues (2025). Environmental consequences of interacting effects of changes in stratospheric ozone, ultraviolet radiation, and climate: UNEP Environmental Effects Assessment Panel, Update 2024. Photochemical and Photobiological Sciences. https://doi.org/10.1007/s43630-025-00687-x Dreyfus, G. B., Montzka, S. A., Andersen, S. O., and Ferris, R. (2024). Technical note: A method for calculating offsets to ozone depletion and climate impacts of ozone-depleting substances. Atmospheric Chemistry and Physics, 24(3). https://doi.org/10.5194/acp-24-2023-2024 Montzka, S. A., Dutton, G. S., Portmann, R. W., Chipperfield, M. P., Davis, S., Feng, W., Manning, A. J., Ray, E., Rigby, M., Hall, B. D., and colleagues (2021). A decline in global CFC-11 emissions during 2018 to 2019. Nature, 590, 428 to 432. https://doi.org/10.1038/s41586-021-03260-5 Park, S., Western, L. M., Saito, T., Redington, A. L., Henne, S., Fang, X., Prinn, R. G., Manning, A. J., Montzka, S. A., Fraser, P. J., and colleagues (2021). A decline in emissions of CFC-11 and related chemicals from eastern China. Nature, 590, 433 to 437. https://doi.org/10.1038/s41586-021-03277-w Velders, G. J. M., Daniel, J. S., Montzka, S. A., Vimont, I., Rigby, M., Krummel, P. B., Muhle, J., O Doherty, S., Prinn, R. G., Weiss, R. F., and Young, D. (2022). Projections of hydrofluorocarbon emissions and the resulting global warming based on recent trends in observed abundances and current policies. Atmospheric Chemistry and Physics, 22(9), 6087 to 6101. https://doi.org/10.5194/acp-22-6087-2022 Wang, P., Solomon, S., Santer, B. D., Kinnison, D. E., Fu, Q., Stone, K. A., Zhang, J., Manney, G. L., and Millan, L. F. (2025). Fingerprinting the recovery of Antarctic ozone. Nature, 639, 646 to 651. https://doi.org/10.1038/s41586-025-08640-9 Western, L. M., Vollmer, M. K., Krummel, P. B., Adcock, K. E., Crotwell, M., Fraser, P. J., Harth, C. M., Langenfelds, R. L., Montzka, S. A., Muhle, J., and colleagues (2023). Global increase of ozone-depleting chlorofluorocarbons from 2010 to 2020. Nature Geoscience, 16(4), 309 to 313. https://doi.org/10.1038/s41561-023-01147-w Western, L. M., Daniel, J. S., Vollmer, M. K., Clingan, S., Crotwell, M., Fraser, P. J., Ganesan, A. L., Hall, B. D., Harth, C. M., Krummel, P. B., and colleagues (2024). A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons. Nature Climate Change, 14(8), 805 to 807. https://doi.org/10.1038/s41558-024-02038-7 World Meteorological Organization (2022). Scientific Assessment of Ozone Depletion: 2022. Global Ozone Research and Monitoring Project, GAW Report No. 278. World Meteorological Organization, Geneva. Young, P. J., Harper, A. B., Huntingford, C., Paul, N. D., Morgenstern, O., Newman, P. A., Oman, L. D., Madronich, S., and Garcia, R. R. (2021). The Montreal Protocol protects the terrestrial carbon sink. Nature, 596, 384 to 388. https://doi.org/10.1038/s41586-021-03737-3

The 1985 #Vienna_Convention for the Protection of the Ozone Layer is widely described as the moment when the international community agreed, for the first time, to act together against a global atmospheric threat before that threat had been fully proven. This article reviews the Convention as a legal instrument, as a political achievement, and as the foundation of a regulatory system that has since removed more than ninety nine per cent of controlled ozone depleting chemicals from production and consumption. The study uses a qualitative doctrinal method combined with a narrative review of peer reviewed scientific and legal literature published mainly between 2021 and 2026. It examines the scientific discoveries that made the treaty necessary, the negotiating history that shaped its cautious wording, the specific duties it created, the institutions it established, and the way those institutions allowed a modest agreement to grow into the most detailed chemical control regime in international law. The article then assesses the measurable results, including the first statistically rigorous evidence that the Antarctic #ozone_hole is healing, the very large climate benefits that were obtained as a side effect, and the health and ecological damage that was avoided. Finally, the article identifies the problems that remain unsolved, including emissions from chemical feedstocks, unexpected releases of banned substances, unregulated gases such as nitrous oxide, and the possible ozone risks of proposed climate intervention technologies. The conclusion is that the Convention succeeded not because it contained strong rules, but because it created a durable structure in which strong rules could later be written, financed, monitored, and enforced. That structure, rather than the text itself, is the part most worth copying. Keywords: ozone layer; framework convention; international environmental law; ozone depleting substances; Montreal Protocol; treaty design; atmospheric governance 1. Introduction Few international agreements are described by diplomats, scientists, and lawyers alike as a success. The system built on the 1985 Convention adopted in Vienna is one of them. Over four decades it has taken a class of chemicals that were once found in almost every refrigerator, aerosol can, fire extinguisher, and foam mattress in the industrialised world, and has removed them from ordinary commerce almost completely. It has done this while keeping every single member state of the United Nations inside the agreement, and while giving developing countries the money and the technical help they needed to comply. Yet the Convention itself contains almost no binding limits on anything. It does not name a single chemical that must be reduced. It does not set a date, a percentage, or a penalty. Read on its own, it looks like a statement of good intentions. This apparent weakness is the central puzzle that this article addresses. How did a treaty that promised so little become the legal parent of a regime that delivered so much? The answer lies in the idea of the #framework_convention. A framework treaty does not try to solve the problem at the moment of signature. Instead, it establishes the shared understanding, the institutions, the reporting duties, and the procedures through which parties can agree on binding measures later, as the science becomes clearer and as political resistance weakens. The 1985 Convention was drafted at a time when the chemical industry, several major governments, and a significant part of the scientific community still doubted that ozone loss was real, measurable, or urgent. A treaty with hard numbers would have failed. A treaty with an open architecture succeeded, and two years later that architecture carried the #Montreal_Protocol, which did contain hard numbers. This article has four aims. The first is descriptive: to explain, in plain language, what the Convention actually says and what it actually requires. Much of the popular writing on this topic skips straight to the Protocol and treats the Convention as a footnote. That is a mistake, because the Protocol could not exist without it. The second aim is analytical: to explain why the design choices made in Vienna worked, and under what conditions they might not work elsewhere. The third aim is evaluative: to summarise, using recent peer reviewed evidence, what the regime has achieved for the atmosphere, for human health, for ecosystems, and for the climate. The fourth aim is critical: to set out honestly the gaps, loopholes, and emerging threats that could still undo part of the achievement. The article is written for students of environmental law, international relations, atmospheric science, and public policy. It assumes no prior technical knowledge. Chemical and legal terms are explained where they first appear. 1.1 Research questions The study is organised around five questions. What scientific and political conditions produced the 1985 Convention, and how did those conditions shape its content? What legal obligations does the Convention impose, and how do these obligations differ from those in later instruments? Through what institutional mechanisms did a non binding framework generate binding, enforceable, and financed controls? What measurable environmental, health, and climate outcomes can be attributed to the regime, according to recent evidence? What weaknesses remain, and what lessons, if any, can be transferred to other global environmental problems? 1.2 Significance of the study Two developments make this review timely. First, 2025 marked the fortieth anniversary of the Convention, and the same year produced the strongest scientific confirmation yet that the ozone layer is genuinely recovering rather than merely fluctuating. Second, the international community is currently attempting to negotiate new global agreements on plastics, on chemicals, and on climate finance, and negotiators repeatedly invoke the ozone regime as the model to follow. If that model is to be copied intelligently, it must first be understood accurately, including its limits. 2. Background: The Science That Forced a Treaty 2.1 What the ozone layer is and why it matters Ozone is a molecule made of three oxygen atoms. Near the ground it is a pollutant and an irritant. High above the ground, in the region of the atmosphere called the #stratosphere, it performs an entirely different job. Roughly nine to nineteen miles above the surface, ozone is concentrated enough to absorb most of the incoming solar #ultraviolet_radiation in the biologically damaging wavelengths. Without that absorption, the amount of ultraviolet energy reaching the surface of the planet would rise sharply. This thin shield is not thick. If all the ozone in the column above a given point were brought down to sea level pressure, it would form a layer only about three millimetres deep. Life on land evolved under its protection, and terrestrial organisms have limited defences against a large and rapid increase in ultraviolet exposure. The consequences of losing ozone are therefore biological rather than merely atmospheric. Higher ultraviolet exposure increases rates of #skin_cancer and eye disease, particularly #cataracts. It suppresses immune responses. It damages plant tissue and reduces photosynthetic productivity. It harms the microscopic marine organisms, especially #phytoplankton, that form the base of ocean food webs and that absorb large quantities of carbon dioxide. Recent assessment work by the environmental effects panel that advises the treaty parties has emphasised that these effects do not occur in isolation; they interact with warming, with changing cloud cover, and with shifts in where organisms live, producing combined outcomes that are harder to predict than any single stressor alone (Neale et al., 2025). 2.2 The chemical hypothesis The chemicals at the centre of the story are #chlorofluorocarbons, usually abbreviated as CFCs. They were invented in the late 1920s and were, from an industrial point of view, close to perfect. They are non toxic, non flammable, stable, cheap, and efficient. They were used as refrigerants, as propellants in spray cans, as solvents for cleaning electronic components, and as blowing agents for plastic foams. Their commercial virtues came from their chemical stability, and that stability turned out to be exactly the problem. Because CFCs do not react easily, they are not washed out of the lower atmosphere by rain and are not broken down by ordinary chemical processes near the surface. They drift upward over years and decades until they reach the stratosphere, where intense ultraviolet light finally splits them apart. That split releases #chlorine atoms. A single chlorine atom can then destroy ozone molecules in a repeating #catalytic_cycle, in which the chlorine is regenerated at the end of each cycle and is free to attack again. One chlorine atom can therefore destroy many thousands of ozone molecules before it is eventually removed from the stratosphere. Similar chemistry applies to #bromine released from other compounds, and bromine is, atom for atom, considerably more destructive than chlorine. This hypothesis was published in 1974 by two chemists working in the United States, and their argument became the foundation of the whole regulatory edifice that followed. The proposal was, at the time, deeply controversial. It rested on laboratory chemistry and atmospheric modelling rather than on direct observation of ozone loss. Industry representatives argued, not unreasonably, that no damage had actually been measured. The #Rowland_and_Molina hypothesis was thus a prediction of future harm, not a report of present harm, and this is precisely why it created such a difficult problem for policymakers. 2.3 From hypothesis to observation Between the mid 1970s and the mid 1980s, governments responded unevenly. Some countries, including the United States, Canada, Norway, and Sweden, banned CFCs in aerosol sprays. Others, particularly in Europe, resisted, arguing that the evidence was speculative and the economic cost of substitution was high. Attempts to negotiate a global agreement during this period repeatedly stalled on exactly this point: the science was suggestive but not conclusive, and no state wanted to impose costs on its own industry that competitors would not bear. Then, in the same year that the Convention was signed, a team from the #British_Antarctic_Survey published measurements from Halley Bay showing that springtime ozone above Antarctica had fallen dramatically since the late 1970s. The loss was far larger and far faster than any model had predicted. The satellite record, once re examined, confirmed it. This phenomenon became known to the public as the ozone hole, although it is more accurately described as a severe seasonal thinning rather than a true hole. The timing matters for the legal history. The Antarctic measurements were published only weeks after the Convention was adopted. The negotiators in Vienna therefore did not have this evidence in front of them. They agreed to act while the case was still contested. This is the strongest available example of what lawyers call the #precautionary_principle operating in practice, before that principle had even been given its familiar name in international instruments. 2.4 Why Antarctica The severity of the Antarctic loss was not predicted because it depends on a mechanism that early models did not include. During the polar winter, the air over Antarctica becomes isolated inside a circulating wind system called the polar vortex, and temperatures fall low enough for #polar_stratospheric_clouds to form. The surfaces of the particles in these clouds allow chemical reactions that convert chlorine from inactive reservoir compounds into highly reactive forms. When sunlight returns in the southern spring, this stored reactive chlorine destroys ozone extremely rapidly. The result is a deep, seasonal, and geographically concentrated collapse in ozone concentrations, which then partially recovers as the vortex breaks down and ozone rich air mixes in from lower latitudes. Understanding this mechanism was essential for policy, because it explained why the ozone hole appears where and when it does, why it varies so much from year to year with meteorological conditions, and why detecting genuine recovery would require careful statistical work rather than simple visual inspection of annual maps. 3. Methodology 3.1 Research design This article uses a qualitative, interpretive design that combines two established approaches. The first is doctrinal legal analysis. This means reading the primary legal text of the Convention closely, article by article, in order to establish what obligations exist, how they are phrased, how strong or weak that phrasing is, and how the provisions relate to one another and to later instruments. Doctrinal analysis is the standard method of legal scholarship and is appropriate here because the central research questions concern the content and effect of a legal instrument. The second is a narrative literature review. This means identifying, reading, and synthesising the relevant published research, and organising it thematically rather than statistically. A narrative review is appropriate where the literature spans several disciplines that use incompatible methods, as is the case here, since the relevant work includes atmospheric chemistry, satellite data analysis, epidemiology, economics, political science, and law. A meta analysis would not be meaningful across such different evidence types. 3.2 Sources and selection criteria Sources were selected according to four criteria. Recency. Priority was given to peer reviewed material published between 2021 and 2026. This restriction is deliberate. The scientific picture of ozone recovery changed substantially during this period, and older assessments, however influential, no longer represent the state of knowledge. Where an older source is unavoidable because it reports a foundational discovery, that source is described in the text rather than relied upon for current claims. Peer review. Journal articles and formal international #scientific_assessment reports were preferred over commentary, advocacy material, and news reporting. Where an advocacy organisation has published in a peer reviewed journal, the peer reviewed version is used. Disciplinary balance. The review deliberately includes atmospheric science, legal scholarship, and political analysis, because the research questions cannot be answered from within any one of these fields. Traceability. Every factual claim about ozone concentrations, emissions, projections, or treaty membership is drawn from an identifiable published source and is not reconstructed from memory or inference. 3.3 Analytical framework The analysis is organised around four dimensions of treaty performance that are commonly used in the study of international regimes. Output refers to the rules, decisions, and institutions the regime produces. Outcome refers to the changes in behaviour by states, firms, and consumers that follow. Impact refers to the change in the environmental problem itself. Legitimacy refers to whether the arrangement is regarded as fair enough by the parties to keep them inside it. A regime can score well on one dimension and badly on another. A treaty can produce elegant rules that nobody follows, or can change behaviour in ways that fail to fix the underlying problem. Distinguishing these dimensions allows a more honest assessment than a simple verdict of success or failure. 3.4 Limitations of the method Three limitations should be stated at the outset. First, attributing environmental improvement to a legal instrument always involves counterfactual reasoning, and counterfactuals cannot be observed directly; they must be modelled. Second, the regime is unusually well documented and unusually admired, and there is a risk that the literature itself is biased toward positive findings. The article addresses this by devoting substantial space to failures and loopholes. Third, doctrinal analysis reveals what a text requires, not what states actually do, and the gap between the two is bridged here only by reference to secondary evidence. 4. The Negotiating History and the Logic of Framework Design 4.1 The problem facing negotiators By the early 1980s the United Nations Environment Programme, referred to here as #UNEP, had convened a series of meetings aimed at producing a global instrument on ozone protection. The negotiators faced a structural difficulty that recurs in almost every global environmental problem, and which political scientists describe as a #collective_action_problem. The ozone layer is a #global_public_good. Nobody can be excluded from its protection, and one country's enjoyment of it does not reduce another's. This means that any state that reduces its emissions bears the full cost of doing so but receives only a fraction of the benefit, since the benefit is spread across all states. The rational short term strategy for each individual state is therefore to let others pay while continuing to emit, a behaviour known as #free_riding. Unless this incentive is changed, cooperation collapses. Compounding this, the states involved had sharply different interests. A small number of industrialised countries produced most of the world's CFCs. Developing countries produced very little but were beginning to industrialise, and expected to expand refrigeration and air conditioning rapidly as incomes rose. Several European producers had large export markets to protect. The United States had already restricted aerosol uses and therefore had an interest in seeing competitors face similar restrictions. Scientific uncertainty gave every reluctant party a respectable reason to delay. 4.2 The choice of a framework Faced with these divisions, the drafters chose not to attempt a substantive agreement. Instead they produced an instrument that did three things: it recorded a shared recognition that human activities can modify the ozone layer and that such modification can cause harm; it committed parties to cooperate on research, monitoring, and the exchange of information; and it created the legal machinery through which future binding measures could be adopted. This is what is meant when the Convention is called a framework instrument. The choice reflects a general lesson about #treaty_design: where scientific uncertainty is high and interests are divided, the most valuable thing a treaty can do is not to fix the rules but to fix the process. Rules made under uncertainty are either too weak to matter or too rigid to survive new evidence. A process, by contrast, can absorb new evidence and convert it into rules at the speed the evidence allows. The Convention was adopted in Vienna on 22 March 1985 and entered into force on 22 September 1988. Just over twenty states, together with the European Community, signed at the outset. It has since been ratified by every member of the United Nations, an outcome usually described as #universal_ratification and one that no other environmental agreement of comparable scope has achieved. 4.3 The role of scientists in the negotiation An important feature of the ozone negotiations, repeatedly stressed in the political science literature, is the influence of an organised international community of researchers who shared a common understanding of the problem and who were trusted by governments on all sides. Scholars call such a group an #epistemic_community. Because the same body of scientists advised delegations from countries with opposing economic interests, disagreements could be narrowed to genuine questions of fact rather than being conducted through competing sets of national data. This arrangement was later formalised. The regime created standing assessment panels covering science, environmental effects, and technology and economics. Their periodic reports are not negotiated documents in the political sense; they are expert syntheses. Parties may argue about what to do in response, but they generally do not argue about what the reports say. This separation of the factual question from the political question is one of the regime's most important and least imitated features, and it is what practitioners mean when they refer to a functioning #science_policy_interface. 5. The Legal Architecture of the Convention This section examines the operative provisions. The purpose is to show precisely how much, and how little, the Convention actually requires, and to identify the provisions that turned out to matter most. 5.1 Objective and definitions The Convention opens by defining the ozone layer, adverse effects, alternative technologies, and related terms. Definitions in a framework treaty are not decorative. They determine the scope of everything that follows, and by defining adverse effects to include changes in the physical environment that are harmful to human health, to natural ecosystems, and to materials useful to humanity, the drafters ensured that later protocols could address a wide range of consequences rather than a narrow one. 5.2 General obligations The core duty appears in Article 2. Parties must take appropriate measures to protect human health and the environment against the adverse effects that result, or are likely to result, from human activities that modify or are likely to modify the ozone layer. The wording rewards close reading. The phrase likely to result extends the duty to anticipated harm and not merely to harm that has already occurred. That is the precautionary logic in operation. But the phrase appropriate measures leaves each party to determine what is appropriate, and the article goes on to qualify the duty by reference to the means at a party's disposal and its capabilities. Parties are further asked to cooperate through systematic observations, research, and information exchange, to adopt legislative or administrative measures, and to harmonise policies where appropriate. This is what lawyers call an obligation of conduct rather than an obligation of result. Nothing here can be enforced against a state in the way that a specific numerical limit can be. In the vocabulary of international law, the Convention is closer to #soft_law than to #hard_law, even though it is a binding treaty in form. That is not a criticism; it is the design. 5.3 Research and systematic observations Article 3 requires parties to initiate and cooperate in research and #systematic_observations concerning the physical and chemical processes affecting the ozone layer, the health and environmental effects of changes in it, and alternative substances and technologies. Annex I to the Convention sets out, in technical detail, the substances and processes to be studied, including the fully halogenated alkanes, the partially halogenated alkanes, bromine containing compounds, and nitrogen and hydrogen species that participate in ozone chemistry. This article deserves more attention than it usually receives. By committing parties to build and maintain a shared observational record, and by naming in an annex the specific chemical families to be watched, the Convention created the evidentiary basis on which every subsequent control decision depended. Without a trusted, internationally comparable record of atmospheric concentrations, no party could have been persuaded to accept costly restrictions, and no party could later have been caught breaching them. Monitoring is not a supporting activity in this regime. It is the load bearing structure. 5.4 Cooperation in legal, scientific, and technical fields Article 4 requires parties to facilitate and encourage the exchange of scientific, technical, socio economic, commercial, and legal information relevant to the Convention, with Annex II specifying what this #information_exchange should cover. The same article addresses cooperation in developing and transferring technology, taking account of the particular needs of developing countries. This is the seed from which the later financial and #technology_transfer arrangements grew. The inclusion of commercial and socio economic information alongside scientific information is significant. It acknowledges that the obstacle to action was never purely scientific. Governments needed to know whether substitutes existed, what they cost, and who would supply them. 5.5 Transmission of information Article 5 requires parties to report to the Conference of the Parties on the measures they have adopted. Reporting obligations look bureaucratic, but they perform an essential function: they convert private national conduct into shared international knowledge, they make comparison possible, and they create a record against which later claims of #compliance can be tested. 5.6 The Conference of the Parties Article 6 establishes the #Conference_of_the_Parties, the supreme decision making body. Its mandate is to keep implementation under continuous review, to review the scientific information on the ozone layer and its possible modification, to promote the harmonisation of policies and measures, to adopt programmes for research and observation and for technology transfer, and to consider and adopt protocols, amendments, and annexes. The word continuous is doing important work. The Convention does not treat the problem as settled at the moment of signature. It institutionalises permanent revisitation. A body that meets regularly, receives expert reports, and has the power to adopt new instruments is a body that can respond to new evidence without renegotiating the underlying treaty. 5.7 The Secretariat Article 7 establishes a secretariat, which in practice became the #Ozone_Secretariat administered by UNEP. Its functions include arranging meetings, receiving and transmitting information reported by parties, preparing reports, and coordinating with other international bodies. A permanent secretariat gives a regime memory, continuity, and administrative capacity that rotating national delegations cannot provide. 5.8 Protocols, amendments, and annexes Articles 8, 9, and 10 set out the procedures for adopting protocols, amending the Convention or its protocols, and adopting or amending annexes. These procedural articles are, in retrospect, the most consequential in the entire instrument. They are the doors through which every substantive rule later entered. Two features are worth noting. First, annexes can be adopted and amended by a procedure that is faster and simpler than full treaty amendment, which allows the technical lists that identify controlled substances to be updated as chemistry and industry evolve. Second, the Convention explicitly contemplates protocols, so the parties did not need to construct a new legal basis when they were ready to impose actual limits. The path was already built. All that was required was the political will to walk down it. 5.9 Dispute settlement Article 11 provides for the settlement of disputes by negotiation, and failing that by good offices or mediation. Parties may declare that they accept compulsory arbitration or the jurisdiction of the International Court of Justice. Where these are not accepted, a conciliation procedure may be invoked, producing a recommendation that the parties are to consider in good faith. In practice this machinery has never been the mechanism by which the regime handles non compliance. That role was taken by an entirely different and far more effective procedure created later under the Protocol, discussed in section 7. The contrast is instructive: adversarial dispute settlement, which is the classical legal remedy, proved almost irrelevant, while a cooperative, non punitive procedure proved indispensable. 5.10 What the Convention does not do It is worth stating plainly what is absent. There is no list of banned chemicals. There is no reduction schedule. There are no trade restrictions. There is no fund. There is no compliance committee. There are no sanctions. Every one of these appears later, and none of them appears in 1985. An observer in 1985 could reasonably have concluded that the Convention was a diplomatic gesture designed to look like action while avoiding it. That observer would have been wrong, but not obviously wrong. What made the difference was not the text; it was what the parties chose to build on top of it within the following four years. 6. From Framework to Control: The Montreal Protocol and Its Amendments 6.1 The 1987 Protocol The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in 1987, only two years after Vienna, and entered into force in 1989. It was negotiated under the authority of the Convention's protocol provisions and it is legally a child of that instrument, not a replacement for it. Parties to the Protocol must be parties to the Convention. The original Protocol was modest by later standards. It required the phased reduction of the production and consumption of a specified group of CFCs and #halons, with developed countries reducing the listed CFCs to half of their 1986 levels by the end of the century. It applied a differentiated timetable to developing countries. It included provisions on trade with non parties, a mechanism that turned out to be central to the regime's success. Two design features deserve emphasis. The first is the concept of controlled substances defined by annex, each assigned an #ozone_depletion_potential, a number expressing how much damage a kilogram of that chemical does relative to a kilogram of the reference compound. This allows different chemicals with different potencies to be aggregated into a single controlled quantity, which in turn allows a party to be given one overall obligation rather than dozens of separate ones. It gives industry flexibility in how to comply, while keeping the environmental total fixed. The second is the regulation of production and consumption rather than emissions. Emissions from millions of dispersed appliances cannot be measured directly. Production, by contrast, occurs in a relatively small number of chemical plants, and consumption is calculated from production plus imports minus exports. The regime therefore chose to regulate the point in the chain where measurement was feasible. This is one of the most transferable lessons in the entire field: regulate where you can count. 6.2 The #adjustment_procedure The Protocol introduced an unusual and powerful device. Where the parties wish to tighten an existing control, for example by accelerating a phase out schedule or revising an ozone depletion potential, they may do so by an adjustment, which becomes binding on all parties without requiring each of them to ratify it separately. Adding a new substance to the controlled list still requires a formal amendment, with ratification. But the ability to strengthen existing commitments by decision of the #Meeting_of_the_Parties, rather than by fresh treaty ratification in every national parliament, removed the single greatest source of delay in international lawmaking. This is why the regime was able to move so quickly once the Antarctic evidence and later assessments arrived. Within five years of the original Protocol, the timetable had been transformed from a fifty per cent reduction to complete elimination. 6.3 The amendments The Protocol has been strengthened repeatedly. The London Amendment of 1990 accelerated the phase out and, crucially, created the financial mechanism discussed below. The Copenhagen Amendment of 1992 brought forward the elimination dates and added #hydrochlorofluorocarbons, #methyl_bromide, and #carbon_tetrachloride to the control regime. Later amendments agreed in Montreal in 1997 and in Beijing in 1999 introduced licensing systems for trade in controlled substances and extended controls further. The pattern is consistent. Each new scientific assessment produced evidence that the problem was worse or more urgent than previously believed, and each round of negotiations converted that evidence into tighter obligations. The institutional loop between assessment and regulation functioned as intended. 6.4 The Kigali Amendment and the climate turn The most recent major development is the #Kigali_Amendment of 2016, which entered into force at the beginning of 2019. Kigali addresses a problem created by the regime's own success. As CFCs and then HCFCs were removed, industry turned to #hydrofluorocarbons, known as HFCs. These contain no chlorine and therefore do not deplete ozone. From the point of view of the original treaty they were a perfect solution. But they are potent #greenhouse_gases, in some cases thousands of times more powerful per unit mass than carbon dioxide, and their use was growing rapidly with the global expansion of air conditioning and #refrigeration. Kigali commits parties to phase down the production and consumption of HFCs, using the same architecture of baselines, schedules, differentiated timetables, and financial support that had already been proven. Analysis in the peer reviewed literature indicates that the amendment is expected to avoid emissions in the range of roughly 5.6 to 8.7 gigatonnes of carbon dioxide equivalent per year by 2100, and to reduce the warming contribution of HFCs by up to approximately 0.4 degrees Celsius (Perry et al., 2024). Kigali is legally remarkable for a simple reason: it uses an ozone treaty to regulate chemicals that do not harm ozone at all. It was justified on the ground that the HFC problem was created by the ozone regime's own substitution policy, and that the regime therefore had both the responsibility and the institutional capacity to fix it. Whether this reasoning is legally elegant is debatable. That it was effective is not. The negotiation of Kigali also exposed political fractures that had not been visible in earlier rounds. Detailed analysis of the bargaining shows that China and India, the two largest producers of HFCs, adopted sharply different positions and ended decades of cooperation between them, with each attracting different groups of developing countries to its side. The episode illustrates that the #Global_South is not a single bloc with a single interest, and that the meaning of #common_but_differentiated_responsibilities is itself contested among developing states, not only between developed and developing ones (Yang, 2023). 7. Institutional Machinery: Money, Monitoring, and Managed Compliance The Convention created a Conference of the Parties and a secretariat. The Protocol and its amendments added three further institutions that, taken together, explain most of the regime's performance. Each addressed a distinct failure mode that has defeated other agreements. 7.1 The financial mechanism The most important innovation was the #Multilateral_Fund, established under the London Amendment in 1990. Its logic is straightforward. Developing countries had contributed little to the problem, had limited capacity to pay for substitution, and had a legitimate claim to expand refrigeration and cooling as part of their development. Asking them to bear the cost of a problem created elsewhere was neither fair nor realistic. If they refused to join, the phase out would simply relocate rather than disappear. The Fund therefore requires industrialised parties to contribute money, on an agreed scale, which is then used to meet the agreed incremental costs of compliance in developing country parties. Those parties are technically defined by their low per capita consumption of controlled substances and are referred to throughout the regime as #Article_5_countries. The Fund pays to convert factories, to retrain technicians, to establish licensing and customs systems, and to build the domestic administrative capacity needed to implement the treaty at all. Two aspects of the design deserve attention. First, the Fund covers incremental costs, meaning the additional cost of the cleaner option relative to what the country would otherwise have spent. It does not fund development generally. This kept the arrangement politically defensible in donor capitals while still being sufficient to make compliance affordable. Second, the Fund is governed by an executive committee with equal representation from donor and recipient countries, so recipients are not merely applicants but co managers. That parity is one reason the arrangement has retained legitimacy over three decades. The Fund is often described as the first operational expression of the principle of common but differentiated responsibilities in a working treaty. It is also the feature that other negotiations most consistently try to copy, and most consistently fail to reproduce, as recent analysis of the negotiations toward a global #plastics_treaty has noted (Aanesen et al., 2024). 7.2 The compliance system The second institution is the #non_compliance_procedure, operated through an #Implementation_Committee. Its design runs against most legal intuition. When a party fails to meet its obligations, the Committee does not begin by seeking to punish it. It begins by asking why. In the large majority of cases the answer is not deliberate cheating but administrative weakness: a customs service that cannot identify controlled chemicals, a ministry without the staff to compile data, an importer who is not licensed because no licensing system exists. The Committee's normal response is therefore to offer assistance, to agree a plan of action with benchmarks, and to monitor progress. Financial and technical support from the Fund can be directed to help the party return to compliance. Only if a party refuses to cooperate can harder measures follow, including the suspension of rights under the treaty. In practice this end of the ladder is rarely reached. The system works because it treats non compliance as a problem to be solved jointly rather than a wrong to be avenged, and because the incentives for staying inside the system are strong. The seriousness of the mechanism should not be underestimated, however. When unexpected emissions of a banned substance were detected and traced to a producing region, the regime's financial bodies responded with concrete consequences, including reductions in agreed funding, demonstrating that the cooperative approach is backed by real leverage. 7.3 Trade measures The third institution is the set of #trade_measures. The Protocol restricts trade in controlled substances, and in products containing them, between parties and non parties. This provision solved the free riding problem in a direct way. A state that stayed outside the regime would lose access to the markets and the supply chains of those inside it. Because the major producers and the major consumers were all inside, remaining outside became commercially unattractive. Combined with licensing systems for imports and exports, these measures also made #illegal_trade harder, though not impossible. Smuggling of controlled refrigerants has occurred throughout the life of the regime, and it remains a live enforcement problem, particularly where price differences between controlled and uncontrolled substances are large. The trade provisions are sometimes described as coercive, and in a sense they are. But they are also the reason the treaty achieved universal membership. A treaty that everyone joins and that everyone follows is a rare thing, and it was not achieved by appeals to conscience alone. 7.4 National implementation None of the above works without domestic machinery. Under the regime, most developing country parties established #national_ozone_units, small government offices responsible for data collection, licensing, coordination with customs, and liaison with the international institutions. Funding these units, and the associated training, has been one of the Fund's quieter but most consequential activities. This form of #capacity_building converts an international obligation into an administrative routine, and administrative routine is what compliance actually consists of in practice. 8. Evidence of Results 8.1 Reductions in controlled substances The headline output of the regime is the near total elimination of the production and consumption of controlled #ozone_depleting_substances. Assessments by the treaty bodies and by the #World_Meteorological_Organization report that more than ninety nine per cent of the production and consumption of controlled substances has been phased out, and that global consumption has fallen by roughly ninety eight per cent since the Convention entered into force. These are extraordinary figures for any regulatory regime. They reflect the near disappearance of an entire industrial chemical class from the ordinary economy of every country in the world. 8.2 Atmospheric concentrations and projected recovery Because CFCs are long lived, atmospheric concentrations respond slowly. The total chlorine and bromine loading of the stratosphere peaked in the 1990s and has been declining since. Projections in the periodic scientific assessments indicate that, if current controls are maintained, ozone will return to 1980 levels around 2066 over the Antarctic, around 2045 over the Arctic, and around 2040 across the rest of the world. These dates should be read as central estimates, not guarantees. They depend on continued compliance, on the behaviour of gases outside the regime, and on how the stratosphere responds to a changing climate. 8.3 Detecting genuine recovery For many years, a genuine scientific difficulty stood in the way of declaring success. The #Antarctic ozone hole varies enormously from year to year for meteorological reasons that have nothing to do with chemistry. A small hole in one year proves nothing, and a large hole in the next proves nothing either. Distinguishing a real trend from natural noise required a method capable of separating a forced signal from internal variability. That problem was addressed directly in a study published in 2025, which applied pattern based detection and attribution methods, of the kind developed for climate change research, to Antarctic ozone. Rather than examining a single index such as the area of the hole, the authors looked for a characteristic pattern of change, distributed across month and altitude, that would be expected if declining ozone depleting substances were the cause. Using satellite observations together with single model and multi model ensemble simulations, they found that this fingerprint of #ozone_recovery is now detectable with high statistical confidence, and that the recovery is attributable primarily to the reduction of ozone depleting substances rather than to natural variability (Wang et al., 2025). This is the strongest form of evidence available in atmospheric science short of a controlled experiment, which is of course impossible for a planet. It converts a claim that was previously plausible into one that is demonstrated. Independently, the annual monitoring bulletins issued by the World Meteorological Organization have reported that the Antarctic ozone hole in recent years has been smaller and shorter lived than in the immediately preceding period, while cautioning that year to year fluctuations are driven partly by natural atmospheric factors and that no single year establishes a trend. 8.4 Avoided harm to human health Counterfactual analysis, comparing the world as it is with a modelled world in which the treaty was never adopted, indicates very large avoided health burdens. Modelling of the United States population alone has projected that ozone protection will prevent hundreds of millions of skin cancer cases and tens of millions of cataract cases among people born during the period examined. Globally, the assessment panels attribute to the regime the avoidance of a substantial share of the disease burden that would have followed from a large and sustained rise in surface ultraviolet exposure. Recent assessment work stresses that ultraviolet exposure interacts with other environmental changes. Warming alters behaviour, cloud cover, and the distribution of species, so the health and ecological consequences of a given ozone level are not fixed but depend on climatic context (Neale et al., 2025). 8.5 Avoided harm to ecosystems and the carbon cycle The most striking recent finding concerns plants. A modelling study compared a world following the actual regulatory path with a counterfactual world in which CFC use continued to grow at a few per cent per year. In the unregulated world, ultraviolet radiation at the surface rises to several times present levels, and plant tissue damage substantially reduces photosynthetic productivity. Because plants absorb carbon dioxide, reduced plant growth means reduced uptake of carbon. The result is that a large quantity of carbon that would have been stored in vegetation and soils would instead have remained in the atmosphere. The authors estimate that the loss of this #terrestrial_carbon_sink would itself have added a further increment of warming, on top of the direct warming caused by the CFC molecules themselves, which are powerful greenhouse gases in their own right. Taken together, the study concludes that the ozone regime avoided in the region of an additional 2.5 degrees Celsius of global warming by the end of this century relative to the unregulated case (Young et al., 2021). This finding reframes the regime. An agreement negotiated to protect a chemical layer in the upper atmosphere turns out to have been one of the largest climate policies ever enacted, and it was enacted as a by product rather than by design. 8.6 The climate co-benefit and its measurement The climate benefit arises through three separate channels. First, most controlled ozone depleting substances are themselves greenhouse gases with high #global_warming_potential, so eliminating them removed a substantial radiative forcing directly. Second, protecting ozone protected the land carbon sink, as described above. Third, the Kigali Amendment now targets HFCs, which are pure climate pollutants with no ozone effect. It is worth being precise about the relationship between this regime and the broader climate regime. The ozone treaties are not a substitute for the #Paris_Agreement, and their success does not show that #climate_change can be solved the same way. The differences are discussed in section 10. But the ozone regime has almost certainly delivered more measurable avoided warming to date than any instrument negotiated for that purpose. 9. Unfinished Business: Gaps, Loopholes, and Emerging Threats A serious review cannot end with the achievements. The regime has real weaknesses, and several of them are growing rather than shrinking. 9.1 Feedstock uses The most significant structural loophole concerns #feedstock_exemptions. The Protocol restricts the production and consumption of controlled substances for dispersive uses, meaning uses in which the chemical is eventually released. It does not restrict their production for use as a feedstock, that is, as a chemical building block that is consumed inside a factory during the manufacture of some other product. The reasoning was that a chemical which is destroyed in the reaction cannot escape into the atmosphere, so its ozone impact is negligible. That reasoning rested on an assumption about leakage rates. It was assumed that only about half of one per cent of the quantity produced as feedstock would escape. Recent work indicates that this assumption was substantially wrong. A 2026 study estimates that feedstock related emissions represent around 3.6 per cent of the quantity produced under a business as usual scenario over the period to 2100, roughly seven times the figure originally assumed, and that global feedstock use rose by approximately 163 per cent between 2000 and 2024. Without additional measures, the authors project that these emissions could delay the recovery of the mid latitude ozone layer by something in the order of six to eleven years (Reimann et al., 2026). This is a serious finding. It means that a category of production which the regime deliberately chose not to control has grown into a material threat to the regime's central objective. Closing the loophole would require either bringing feedstock production within the control schedules, or imposing binding requirements on emission control and destruction at the plants concerned. 9.2 Unexpected emissions of phased out substances A second problem is the appearance of emissions that should not exist. The best known case involved #CFC_11, whose production for dispersive use had been eliminated globally. Atmospheric measurements showed that its concentration was declining more slowly than expected, which could only mean that new emissions were occurring. Subsequent investigation pointed to unreported production, and after enforcement action the decline resumed its expected trajectory. The episode was a warning: the regime's data depend on national reporting, and national reporting can be wrong or dishonest. Only independent #atmospheric_monitoring caught the discrepancy. A related and continuing problem concerns a group of CFCs whose emissions rose between 2010 and 2020 despite the ban. Measurements combined with atmospheric transport modelling showed that combined emissions of five such compounds increased from roughly 1.6 to roughly 4.2 ozone depletion potential weighted gigagrams per year over that decade. Several of these are probably by products arising during the manufacture of HFCs, the very chemicals introduced as ozone safe replacements. The authors note that at current levels the effect on ozone recovery is small, but that the compounds are potent greenhouse gases and that continued growth would begin to erode the regime's gains (Western et al., 2023). The general lesson is uncomfortable. Substitution can move a problem rather than remove it, and the production process for a clean chemical may not itself be clean. 9.3 Weak measurement, reporting, and verification Both of the problems above point to the same institutional gap. The regime's reporting system was designed to track production and consumption as declared by states. It was not designed to detect emissions that nobody declares. The global network of atmospheric measurement stations is thin in exactly the regions where unreported production is most likely, and there is no treaty obligation to fund or maintain such a network. Strengthening #emission_verification, by expanding regional monitoring and by giving the treaty bodies a clearer mandate to investigate discrepancies between reported production and observed concentrations, is among the most frequently recommended reforms in the recent literature (Perry et al., 2024). 9.4 Banks A further category of risk is contained in existing equipment. Very large quantities of controlled substances remain inside refrigeration systems, air conditioners, insulating foams, and fire suppression equipment that are still in service or that have been discarded. These reservoirs are known as the #banks_of_ozone_depleting_substances. Because the Protocol regulates production and consumption rather than emissions, banked material is essentially unregulated. If it leaks, or is vented at end of life rather than recovered and destroyed, it will reach the stratosphere regardless of the fact that its production ceased decades ago. Policies aimed at recovering, reclaiming, and destroying banked material, sometimes grouped under the heading of #lifecycle_refrigerant_management, offer large and comparatively cheap benefits for both ozone and climate, and remain largely voluntary. 9.5 Substances outside the regime Several ozone relevant chemicals are not controlled at all. The most important is #nitrous_oxide. It is emitted mainly from agriculture, particularly from nitrogen fertiliser use, and from certain industrial processes. It destroys stratospheric ozone through a chemical pathway different from that of chlorine, and it is also a powerful greenhouse gas. It is not controlled by the ozone regime, and its emissions have been rising. Recent modelling of agricultural mitigation strategies finds that reducing these emissions delivers meaningful climate benefits, although the estimated effect on the pace of stratospheric ozone recovery in the scenarios examined was modest (Weber et al., 2024). The policy point stands regardless: a major remaining ozone depleting emission is governed by no ozone treaty. A second category is that of #very_short_lived_substances. These are chlorinated compounds, such as certain industrial solvents, with atmospheric lifetimes measured in months rather than decades. Because they break down quickly, it was long assumed that little of them would survive the journey to the stratosphere. Growing evidence suggests that a non trivial fraction does, particularly where emissions occur in tropical regions with strong vertical transport. Their use has been increasing, and they remain uncontrolled. 9.6 Chemical substitution and new pollutants The regime's method has always been substitution: identify a harmful chemical, encourage a replacement, control the original. Each round of substitution has produced a new question. CFCs gave way to HCFCs, which still deplete ozone and were therefore controlled in turn. HCFCs gave way to HFCs, which do not deplete ozone but warm the planet, and were therefore controlled by Kigali. HFCs are now giving way to unsaturated fluorinated compounds with very short lifetimes and very low warming potential. These newest substitutes degrade in the atmosphere into persistent breakdown products, including #trifluoroacetic_acid, which accumulates in water bodies. The assessment panels have examined this question and the current view is that projected concentrations remain below levels of established concern, but the issue is under active study. The broader point is structural: a regime built on substitution must keep asking what the substitute does, and must retain the institutional capacity to regulate it if the answer turns out badly. 9.7 Climate intervention A newer and more speculative risk comes from proposals to cool the planet by injecting reflective particles into the stratosphere, an approach usually described as #stratospheric_aerosol_injection. Modelling summarised by the treaty's environmental effects panel indicates that while such an intervention would lower surface temperatures, it would also alter stratospheric chemistry in ways that could deplete ozone, and would change precipitation patterns, with large uncertainties throughout (Neale et al., 2025). This creates a potential conflict between two environmental objectives, and it raises a governance question that no existing institution is clearly authorised to answer. The ozone regime has both the scientific machinery and a legal mandate to take an interest in anything that modifies the ozone layer, and the language of Article 2 of the Convention is broad enough to cover deliberate stratospheric intervention. Whether the parties will choose to exercise that competence is an open question. 10. Discussion: Why It Worked, and What Travels 10.1 Six enabling conditions Reading the history and the literature together, six conditions appear to have made the ozone regime possible. They are worth separating, because the question of whether the model can be copied depends entirely on whether these conditions exist elsewhere. A small number of substances. The problem could be reduced to a defined and finite list of chemicals. Lists can be annexed, amended, and audited. Diffuse problems that cannot be reduced to a list are much harder to regulate by treaty. A small number of producers. Global production was concentrated in a limited number of firms in a limited number of countries. Regulating a few dozen chemical plants is administratively feasible. Regulating billions of emitting devices is not, which is exactly why the regime chose to control production rather than emissions. Available substitutes. This may be the single most important condition. Once alternatives existed, or were credibly close to existing, the political cost of a ban collapsed. Comparative analysis of past pollution treaties finds that the decision to ban or discontinue a harmful substance has depended above all on whether a viable substitute was available, and that environmental concern alone has rarely been sufficient (Aanesen et al., 2024). The corollary is that a treaty which bans something for which no substitute exists is a treaty that will be broken. A shifting industrial interest. Producers initially resisted, but once the major firms had invested in developing replacements, their commercial interest changed. A company holding patents on the substitute has a strong incentive to see the original chemical banned worldwide. #Industry_innovation and #regulatory_certainty reinforced one another: firms invested because regulation was coming, and regulation became politically possible because firms had invested. This alignment is fortunate rather than typical, and the resulting #policy_learning should not be mistaken for a general law of environmental politics. Money for the poorer parties. Without the Fund, developing countries would have had every reason to refuse, and refusal would have been legitimate. Financial transfer converted a demand into a bargain. Trusted, institutionalised science. The assessment panels made it very difficult for any party to sustain a factual position that the international scientific community did not share. 10.2 The limits of the analogy with climate change Because the ozone regime worked, it is constantly proposed as a template. The proposal deserves scepticism. Climate change differs from ozone depletion on almost every one of the six conditions. The relevant emissions come not from a defined list of speciality chemicals but from energy, transport, agriculture, industry, and land use, which together constitute most of the economic activity of the human species. The emitters are not dozens of chemical plants but billions of homes, vehicles, farms, and factories. Substitutes exist for some uses and not for others, and the cost of substitution is measured in trillions rather than billions. Fossil fuel producers are not positioned to profit from the transition in the way that chemical manufacturers were positioned to profit from replacing CFCs. And the scientific consensus, though far stronger than the ozone consensus was in 1985, has been subjected to a scale of organised political contestation that ozone science never faced. The honest conclusion is that the ozone regime is not a template for climate policy, and that treating it as one has probably wasted time. What it offers is not a solution to be copied but a set of design principles to be adapted. 10.3 What actually travels Four features do appear to be portable. The first is the framework and protocol structure itself. Beginning with an agreement on process, institutions, and information, and adding substantive rules later, is a rational response to uncertainty. It has since been used, with varying success, in several other #multilateral_environmental_agreement contexts. The second is the separation of assessment from negotiation. Giving expert panels a formal, standing role, and insulating their findings from line by line political editing, changes the character of the negotiation that follows. The third is the managed, assistance based approach to non compliance. Treating a struggling party as a partner in need of help, rather than as a defendant, keeps parties inside the regime and produces better environmental results than adversarial enforcement. The fourth is the linkage of obligations to finance. A duty that a party cannot afford to perform is not really a duty. The Fund made obligations performable, and in doing so made them credible. Scholars examining other global problems have made precisely these points. Work on the global governance of antimicrobial resistance, for example, has drawn on the ozone experience to argue for institutionalised scientific assessment, dedicated financial support for lower income countries, and flexible instruments that can be tightened over time, while cautioning that the underlying problem structure differs and that direct transplantation would fail (Nanyangwe-Moyo et al., 2024). 10.4 Fairness and the meaning of differentiation The Fund is usually presented as the regime's answer to the question of fairness, and to a considerable extent it is. But the Kigali negotiations showed that differentiation is not a settled concept. As developing economies diverge, the category of developing country ceases to describe a common interest. Two states may both qualify as Article 5 parties while having entirely opposed industrial positions, as the divergence between the two largest HFC producers demonstrated (Yang, 2023). This matters for the future of the regime and for #environmental_governance generally. A differentiation rule based on a category fixed decades ago will eventually become a source of grievance rather than a source of legitimacy. The regime has so far managed this by negotiating differentiated schedules within the developing country group rather than treating it as a bloc, which is itself an innovation worth noting. 10.5 The cooling paradox and the next frontier There is a further tension that the regime has only begun to address. Demand for cooling is rising rapidly, driven by rising incomes, urbanisation, and rising temperatures. Cooling is not a luxury: it protects food through the #cold_chain, it protects medicines and vaccines, and it protects human life during heat waves. Restricting refrigerants without addressing cooling demand would be both unjust and futile. The regime's response has been to link the refrigerant transition to #energy_efficiency. If equipment is replaced anyway, replacing it with more efficient equipment delivers a second, and possibly larger, climate benefit through reduced electricity consumption. Building the standards, testing infrastructure, and certification systems needed to capture that benefit is a task that sits partly inside the ozone regime and partly outside it, and coordinating the two is an unresolved institutional problem. Framed this way, the ozone regime intersects directly with #sustainable_development objectives, since access to affordable cooling is a development question before it is an atmospheric one. 10.6 Exemptions as a design feature and a risk The regime has always allowed exceptions. #Essential_use_exemptions permitted continued production of controlled substances for applications, such as certain medical inhalers, where no adequate alternative existed and where the health consequences of a ban would have been severe. Similar exemptions have applied to specific agricultural and laboratory uses. Exemptions are politically necessary. A regime with no flexibility invites either defection or refusal to ratify. But they are also where regimes leak. The feedstock problem described earlier began as a reasonable exception and became a structural weakness. The lesson is not that exemptions should be abolished but that every exemption should carry a sunset clause, a reporting requirement, and a periodic review against the assumption that justified it. In the ozone regime, the exemption survived while the assumption behind it quietly stopped being true. 11. Limitations of This Study This article is a synthesis and does not generate new empirical data. Four limitations follow. First, the assessment of impact depends on modelled counterfactuals. Statements about avoided cancers, avoided warming, and avoided carbon losses are model outputs, not measurements, and they carry the uncertainties of the models that produced them. They are nonetheless the best available estimates and are drawn from peer reviewed sources. Second, the article treats the regime as a single object, when in practice implementation varies enormously between parties. A study of national implementation in specific jurisdictions would produce a more textured, and probably less flattering, picture. Third, the review is restricted to English language literature, which under represents scholarship produced in the countries where much of the world's remaining production and consumption now occurs. Fourth, the legal analysis is doctrinal rather than empirical. It examines what the instruments say and how the institutions are designed. It does not measure how officials actually behave inside those institutions, which would require interview based research. 12. Directions for Future Research Five questions appear to be both important and open. The first concerns feedstocks. If leakage rates are as high as recent estimates suggest, what regulatory instrument would be most effective, and what would it cost the chemical industry to comply? This is an empirical economic question that has not yet been answered adequately. The second concerns verification. What would an adequate global atmospheric monitoring network cost, who would fund it, and what legal mandate would allow the treaty bodies to act on discrepancies it revealed? The third concerns banks. What policy instruments, at national level, actually succeed in recovering refrigerants at end of life, and why do most jurisdictions perform so poorly at this? The fourth concerns governance of unregulated substances. Is it preferable to extend the ozone regime to cover nitrous oxide and very short lived substances, or to address them through agricultural and chemicals policy instruments, and what are the trade offs? The fifth concerns institutional transfer. Under what specific conditions do the four portable features identified above actually improve outcomes in other regimes, and under what conditions do they fail? Most claims about transferability are asserted rather than tested. 13. Conclusion The 1985 Convention adopted in Vienna is a short document that requires very little. It bans nothing, sets no target, and imposes no penalty. Judged as a piece of substantive regulation, it is close to empty. Judged as a piece of institutional design, it is one of the most successful legal instruments ever written. What it did was to establish, at a moment when the science was contested and the economics were hostile, that ozone depletion was a shared international concern; to commit states to build a common evidentiary record; and to construct the legal doors through which binding measures could later pass. Two years later, the Montreal Protocol walked through those doors. Over the following three decades, the parties adjusted, amended, financed, monitored, and enforced their way to the near total elimination of an entire class of industrial chemicals, achieving universal #ratification along the way. In 2025, statistical attribution methods confirmed that the Antarctic ozone layer is genuinely healing, and that the healing is caused by what was done rather than by chance. The lesson is not that treaties work. Most do not. The lesson is more specific and more useful. Where a problem can be reduced to a list of substances, where the producers are few, where substitutes exist or can be made to exist, where the poorer parties are paid for their compliance, where the facts are established by a body that nobody controls, and where the rules can be tightened without reopening the treaty, then international law can deliver results that are large, measurable, and durable. Where those conditions are absent, invoking the ozone precedent is a rhetorical move rather than a plan. The regime is also unfinished. Feedstock emissions are larger than assumed and may delay recovery by years. Banned chemicals continue to appear in the atmosphere. Enormous quantities of controlled substances sit in old equipment awaiting release. The largest remaining ozone depleting emission is unregulated. New proposals to engineer the climate could damage the layer the treaty exists to protect. None of these problems is beyond the regime's institutional capacity to solve; all of them require the parties to choose to solve them. Forty years after Vienna, the most accurate description of the achievement may be the simplest one. A generation of scientists identified a danger before it became a catastrophe, a generation of diplomats built a structure flexible enough to act on that knowledge as it improved, and a generation of engineers and regulators made the change happen in the real economy. The #ozone_layer is recovering because people decided that it should, and then built the institutions that made the decision stick. That is not a small thing to have learned about ourselves. References Aanesen, M., Ahi, J. C., Abate, T. G., Khan, F. R., de Vries, F. P., Kite-Powell, H., and Beaumont, N. J. (2024). Insights from international environmental legislation and protocols for the global plastic treaty. 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L., Beerling, D. J., and Val Martin, M. (2024). Global agricultural N2O emission reduction strategies deliver climate benefits with minimal impact on stratospheric O3 recovery. npj Climate and Atmospheric Science, 7(1). https://doi.org/10.1038/s41612-024-00678-2 Western, L. M., Vollmer, M. K., Krummel, P. B., Adcock, K. E., Fraser, P. J., Harth, C. M., Langenfelds, R. L., Montzka, S. A., et al. (2023). Global increase of ozone-depleting chlorofluorocarbons from 2010 to 2020. Nature Geoscience, 16, 309-313. https://doi.org/10.1038/s41561-023-01147-w World Meteorological Organization. (2022). Scientific Assessment of Ozone Depletion: 2022. GAW Report No. 278. Geneva: World Meteorological Organization. Yang, S. (2023). Growing apart: China and India at the Kigali Amendment to the Montreal Protocol. Global Environmental Politics, 23(2), 74-101. https://doi.org/10.1162/glep_a_00698 Young, P. J., Harper, A. B., Huntingford, C., Paul, N. D., Morgenstern, O., Newman, P. A., Oman, L. D., Madronich, S., and Garcia, R. R. (2021). The Montreal Protocol protects the terrestrial carbon sink. Nature, 596, 384-388. https://doi.org/10.1038/s41586-021-03737-3 Hashtags #Vienna_Convention_1985 #Ozone_Layer_Protection #Montreal_Protocol_Legacy #Ozone_Depleting_Substances #Stratospheric_Ozone #International_Environmental_Law #Framework_Convention_Model #Kigali_Amendment_HFCs #Ozone_Recovery_Evidence #Multilateral_Environmental_Diplomacy #Atmospheric_Governance #Climate_And_Ozone #World_Ozone_Day #Environmental_Treaty_Design #Global_Environmental_Cooperation