Asser International Sports Law Blog

Our International Sports Law Diary
The Asser International Sports Law Centre is part of the T.M.C. Asser Instituut

New Training - Summer Programme on International sport and human rights - Online - 21-28 May

Since 2022, the T.M.C. Asser Instituut, in collaboration with the Centre for Sport and Human Rights, is organising the first yearly summer course on the intersection of sport and human rights. This 4th edition brings together scholars specialised in the intersection between sport and human rights with professionals working in international sport to ensure respect for human rights. We will explore contemporary human rights challenges in sports, such as the protections of human rights at mega-sporting events, access to remedy in human rights cases within the world of sport, the intersection between human rights and gender rights in international sporting competitions, and many more. 


The programme is designed to provide both deep background knowledge and actionnable insights, which will be relevant to a range of participants committed to defending human rights in international sport, including students, junior researchers, representatives of CSOs, sporting organisations, and athletes. It is structured around half days taking place online meant to accommodate as many participants as possible throughout the world. 


Check out the latest draft programme below and register HERE


Call for Papers - 20 Years of the World Anti-Doping Code in Action - ISLJ Conference 2025 - 6 & 7 November 2025


 


Call for papers

20 years of the World Anti-Doping Code in Action

International Sports Law Journal Conference 2025

Asser Institute, The Hague

6 and 7 November 2025

 

The Editors of the International Sports Law Journal (ISLJ), the Asser Institute and the Research Chair on Responsible Sport of the University of Sherbrooke invite you to submit abstracts for the ISLJ Conference on International Sports Law, which will take place on 6 and 7 November 2025 at the Asser Institute in The Hague. The ISLJ, published by Springer and T.M.C. Asser Press, is the leading academic publication in the field of international sports law and governance. The conference is a unique occasion to discuss the main legal issues affecting international sports with academics and practitioners from all around the world. 

 

The 2025 ISLJ Conference will focus on assessing the first 20 years (2004-2024) of operation of the World Anti-Doping Code (WADC) since its entry into force in 2004, while also discussing its future prospects, in light of the new version of the Code due to be adopted at the Busan Conference in December 2025 and the 10th Conference of the Parties to the International Convention against Doping in Sport, to be held in Paris from 20 to 22 October. The aim of the conference will be to take a comprehensive stock of the operation of the private-public transnational regulatory regime which emerged in the wake of the WADC.  This regime is structured around a complex network of national and global institutions engaged in anti-doping work (WADA, NADAs, IFs, accredited laboratories) and guided by an equally complex assemblage of norms located at the global (WADC and the WADA Standards), international (UNESCO Convention against Doping in Sport), regional (Council of Europe Anti-Doping Convention), and national (various national anti-doping legislations) level. This makes for a fascinating and convoluted transnational legal construct in need of being studied, analysed and criticised by scholars. 

 

Reviewing 20 years of implementation of the WADC warrants a special edition of the ISLJ Conference and of the journal, which invites scholars of all disciplines to reflect on the many questions and issues linked with it. We welcome proposals touching on the following subjects (and more): 

  • The governance of the world anti-doping regime
    • The public-private nature of this governance
    • The transparency of this governance
    • The legitimacy of this governance
    • The participatory nature of this governance
    • The role of scientific experts in this governance
  •  The normative content of the WADC and the international standards
    • The strict liability principle 
    • The privacy rights of athletes under the WADC
    • The sanctioning policy under the WADC
    • The role of the international standards in implementing the WADC
    • The compatibility of the WADC with human rights
  • The glocal implementation of the WADC
    • The role of local institutions (NADOs/Labs/NOCs) in the implementation of the WADC
    • The tension between global (WADA) and local (NADOs/Labs/NOCs) in the implementation of the WADC
    • The role of the IFs in the implementation of the WADC
    • The role of the ITA in the implementation of the WADC
    • The role of judicial bodies (national courts, disciplinary committees of IFs, CAS) and their jurisprudence in the implementation of the WADC 
  • The effectiveness of the world anti-doping regime
    • The evaluation and evolution of the effectiveness of the world anti-doping regime in preventing doping
    • The role of the media in unveiling the ineffectiveness of the world anti-doping regime
    • The role of states in hindering the effectiveness of the world anti-doping regime
    • The world anti-doping regime as a regime with a variable geometry of effectiveness
  •  The future of the world anti-doping regime: Revolution, reform or more of the same?
    • Do we need a world anti-doping regime? 
    • If we do, should it be reformed? How? 


Abstracts of 300 words and CVs should be sent no later than 1 June 2025 to a.duval@asser.nl. Selected speakers will be informed by 30 June 2025. The selected participants will be expected to submit a draft paper by 15 October 2025. Papers accepted and presented at the conference are eligible for publication in a special issue of the ISLJ subject to peer-review. The Asser Institute will provide a limited amount of travel and accommodation grants (max. 350€) to early career researchers (doctoral and post-doctoral) in need of financial support. If you wish to be considered for a grant, please indicate it in your submission.  


Zoom-In Webinar - The Aftermath of the Diarra Judgement: Towards a New FIFA Transfer System? - 20 November - 16:00-18:00 CET

On 4 October, the Court of Justice of the European Union shook the world of football with its Diarra ruling. The decision questions the compatibility of a key provision of the FIFA Regulations on the Status and Transfer of Players (RSTP) with European Union internal market law. The RSTP, and in particular its article 17, are the bedrock of football’s transfer ‘market’ and regulate the conditions for the transnational movement of players between clubs. In 2023, based on FIFA’s numbers, 21 801 players were transferred internationally (of which 3279 with a fee) for transfer fees amounting to USD 9.63 bn. In short, this is a market that affects a considerable number of players and is linked with the movement of large sums of money between clubs and other actors (such as intermediaries).

Register HERE

Join us on 20 November from 16:00 to 18:00 CET to take stock of the ruling's impact and discuss the steps ahead in a free Zoom-In webinar in which there will be time for a Q&A session with the speakers. The ruling has already been much commented on (see hereherehere, and here), and this zoom-in webinar will be an opportunity for participants to engage with two experts on the economic and legal intricacies of the regulation of labour relations in football. We will mostly focus on the aftermath of the judgment and the question, 'what comes next?'

Moderator: Marjolaine Viret (Université de Lausanne)

Speakers: 


Register HERE

Free Webinar - The impact of the Diarra case on the football transfer system - 18 October 2024 - 15:00 CET

The Court of Justice of the European Union has recently handed down its judgement in the Lassana Diarra case (C-650/22 FIFA v. BZ).

Given the importance of this case to the sports industry, LawInSport, the Asser Instituut and the Association for the Study of Sport and the EU (Sport & EU) are hosting a joint webinar to bring together experts to unpack and provide clarity on the complex legal, regulatory & commercial issues stemming from this case. This free webinar will be hosted from 14:00 UK time (15:00 CET) on 18 October 2024.


Register HERE 


Speakers

Our expert speakers come from academia, law and sport. Our confirmed speakers are:


Register HERE 

Conference - ISLJ Annual Conference 2024 - 24-25 October - Asser Institute - The Hague

On 24 and 25 October 2024, the Asser Institute in The Hague will host the 2024 edition of the  International Sports Law Journal (ISLJ)  Conference. The ISLJ is the leading academic journal in transnational sports law and governance and is proud to provide a platform for transnational debates on the state of the field. The conference will address a number of issues of interest to the ISLJ and its readers. 

Register HERE

Drivers and effects of reform in transnational sports governance 

Transnational sports governance seems to be in a permanently unstable state of crisis and reform. At regular interval, international sports governing bodies face scandals triggered by corruption investigations or human rights violations, as well as adverse judidicial decisions. These are often followed by waves of institutional reforms, such as the creation of new bodies (E.g. the Athletics Integrity Unit), the adoption of new codes and regulation (such as Codes of Ethics) or human rights commitments (e.g. FIFA and the IOC’s Human Rights Policy/Strategy). This dynamic of crisis and reform will be at the heart of this year’s ISLJ conference, as a number of panels will critically investigate the triggers, transformative effects and limited impacts of reforms in transnational sports governance.  

Football in the midst of international law and relations 
As the war in Gaza and Russia’s invasion of Ukraine continue to rage, it has become even clearer that the football world can hardly be entirely abstracted from international relations. Yet, FIFA and UEFA continue to insist on their neutrality and to deny that their governance is (or should be) affected by the world’s political affairs. During the conference, we will engage with case studies in which football is entangled with international politics and law. In particular, the speakers will delve into the role of FIFA and UEFA in such situations and on the legal standards and processes that should be applied throughout their decision-making.  

Olympic challenges of today and tomorrow 
While the Paris 2024 Olympics have come to a close, the legal questions they have raised are far from exhausted. Instead, the Olympics have highlighted new issues (such as the question of the legality of the hijab ban imposed by the French Federation on its athletes) or old ones (such as the question whether Olympians should be remunerated by the IOC or the international federations), which will be discussed by our speakers. Finally, with the help of our keynote speaker, Prof. Jules Boykoff, a longstanding critique of the current Olympic regime, we will explore the IOC’s capacity to adapt to challenges while resisting radical change to the current model of olympism.   

Download the full programme 

Online participation available 
Following the success of our webinar option in the past years, we are once again allowing online participation to the conference at an affordable price. Thus, we hope to internationalise and diversify our audience and to reach people who are not in a position to travel to The Hague.  

We look forward to welcoming you in person in The Hague or digitally to this new iteration of the ISLJ conference. 

Register HERE

Speakers 


Register HERE


Conference - Empowering athletes’ human rights: Global research conference on athletes’ rights - Asser Institute - 23 October

The newly launched ‘Global Sport and Human Rights Research Network’, an initiative jointly hosted by the T.M.C. Asser Instituut and the Centre for Sport and Human Rights, together with the European Union-funded project ‘Human Rights Empowered Through Athletes Rights (H.E.R.O.)' is organising an in-person conference on October 23 at the Asser Institute in The Hague, to map the field of athletes' rights and engage in critical discussions on protection of these rights and how to prevent rights violations.

The one-day conference will kick off with a presentation by the H.E.R.O. team on their research results, followed by a short panel discussion. The rest of the day will be filled with four panels on different aspects related to the topic of athletes’ human rights, with speakers from academic institutions around the world.

Check out the full programme HERE and register for free HERE

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Luxembourg calls…is the answer from Nyon the way forward? Assessing UEFA’s response to the ECJ’s ISU judgment - By Saverio Spera

 

Editor's note: Saverio P. Spera is an Italian qualified attorney-at-law. He has practiced civil and employment law in Italy and briefly worked at the Asser International Sports Law Centre before joining FIFA in 2017. Until May 2024, he has worked within the FIFA legal division - Litigation Department, and lectured in several FIFA sports law programmes. In the spring of 2024 he has co-founded SP.IN Law, a Zurich based international sports law firm.

 

 

On 21 December 2023 a judicial hat-trick stormed the scene of EU sports law. That day, the European Court of Justice (the “ECJ”) issued three decisions: (i) European Superleague Company, SL v FIFA and UEFA (Case C-333/21); (ii) UL and SA Royal Antwerp Football Club v Union royale belge des sociétés de football association ASBL (Case C-680/21)and (iii) International Skating Union (ISU) v. European Commission – Case C-124/21.

These judgments were much scrutinised (see herehere and here) in the past 6 months. For the reader’s relief, this paper will not venture into adding another opinion on whether this was a fatal blow to the foundation of EU sports law or if, after all, the substantive change is minimal (as persuasively argued here). It will analyse, instead, UEFA’s recent amendments of its Statutes and Authorisation Rules governing International Club Competitions (the “Authorisation Rules”) and whether these amendments, clearly responding to the concerns raised in the ISU judgment with respect to the sports arbitration system,[1] might pave the way for other Sports Governing Bodies (SGBs) to follow suit and what the implications for CAS arbitration might be. More...

Women’s Football and the Fundamental Right to Occupational Health and Safety: FIFA’s Responsibility to Regulate Female Specific Health Issues - By Ella Limbach

Editor's noteElla Limbach is currently completing her master’s degree in International Sport Development and Politics at the German Sport University Cologne. Her interests include human rights of athletes, labour rights in sport, the intersection of gender, human rights and sport and the working conditions in women’s football. Previously, she graduated from Utrecht University with a LL.M in Public International Law with a specialization in International Human Rights Law. This blog was written during Ella's internship at the Asser Institute where she conducted research for the H.E.R.O. project. The topic of this blog is also the subject of her master's thesis.

Women’s football has experienced exponential growth over the past decade, though the professionalization of the women’s game continues to face barriers that can be tied to the historical exclusion of women from football and insufficient investment on many levels. While attendance records have been broken and media coverage has increased, the rise in attention also highlighted the need for special accommodations for female footballers regarding health and safety at the workplace. Female footballers face gender specific circumstances which can have an impact on their health such as menstruation, anterior cruciate ligament (ACL) injuries and the impact of maternity. As the recent ILO Brief on ‘Professional athletes and the fundamental principles and rights at work' states “gender issues related to [occupational health and safety] risks are often neglected (p. 23).” While it could be argued that from a human rights point of view article 13(c) of the Convention on the Elimination of Discrimination of Women stipulates “the right to participate in […] sports [on an equal basis to men],” reality shows that so far practices of men’s football were simply applied to women’s football without taking into consideration the physiological differences between male and female players and the implications that can have for female players’ health. The ILO Declaration on Fundamental Principles and Rights at Work(ILO Declaration, amended in 2022) includes “a safe and healthy working environment” as one of the fundamental rights at work (Art. 2e). This begs the question whether the scope of the right to occupational health and safety at the workplace includes the consideration of female specific health issues in women’s football. More...

The International Cricket Council and its human rights responsibilities to the Afghanistan women's cricket team - By Rishi Gulati

Editor's note: Dr Rishi Gulati is Associate Professor in International Law at the University of East Anglia (UK) and Barrister in Law. He has a PhD from King’s College London, Advanced Masters in Public International Law from Leiden University, and a Bachelor of Laws from the Australian National University. Amongst other publications, he is the author of Access to Justice and International Organisations (Cambridge University Press, 2022). He has previously worked for the Australian Government, has consulted for various international organizations, and regularly appears as counsel in transnational cases.

On 1 December 2024, Jay Shah, the son of India’s powerful Home Minister and Modi confidante Amit Shah, will take over the role of the Independent Chair of the International Cricket Council (ICC). This appointment reflects the influence India now has on the governance of cricket globally. A key test Jay Shah will face is whether or not the ICC should suspend the Afghanistan Cricket Board (ACB) from its membership as Afghanistan no longer maintains a women’s cricket team contrary to the organization’s own rules, as well as its human rights responsibilities. More...

Asser International Sports Law Blog | Pistorius revisited: A comment on the CAS award in Blake Leeper v. IAAF - By Marjolaine Viret

Asser International Sports Law Blog

Our International Sports Law Diary
The Asser International Sports Law Centre is part of the T.M.C. Asser Instituut

Pistorius revisited: A comment on the CAS award in Blake Leeper v. IAAF - By Marjolaine Viret

On 23 October 2020, a panel of the Court of Arbitration for Sport (‘CAS’) rendered an award in the matter opposing Mr Blake Leeper (‘Mr Leeper’ or ‘the Athlete’) to the International Association of Athletics Federation (‘IAAF’).[1] The CAS panel was asked to make a ruling on the validity of the IAAF rule that places on a disabled athlete the burden to prove that a mechanical aid used to compete in IAAF-sanctioned competitions does not give such athlete an overall competitive advantage.

The award is remarkable in that it declared the shift of the burden of proof on the athlete invalid, and reworded the rule so that the burden is shifted back on the IAAF to show the existence of a competitive advantage. Thus, while the IAAF won its case against Blake Leeper as the panel found that the sport governing body had discharged its burden in casu, the outcome can be viewed as a victory for disabled athletes looking to participate in IAAF-sanctioned events. It remains to be seen how this victory will play out in practice. Beyond the immediate issue at stake, the case further presents an illustration of how – all things equal – assigning the burden of proof can be decisive for the real-life impact of a policy involving complex scientific matters, as much as the actual legal prerequisites of the underlying rules.

This article focuses on some key aspects of the award that relate to proof issues in the context of assessing competitive advantage. Specifically, the article seeks to provide some food for thought regarding burden and degree of proof of an overall advantage, the contours of the test of ‘overall advantage’ designed by the CAS panel and its possible bearing in practice, and potential impact of the ruling on other areas of sports regulations such as anti-doping.

The award also analyses broader questions regarding the prohibition of discrimination in the regulation of sports, as well as the interplay with international human rights instruments such as the European Convention on Human Rights (‘ECHR’), which are not explored in depth here.


1. Some background: from Pistorius to Leeper

In 2008 already, a CAS panel was asked to look into the requirements for participation of disabled athletes using mechanical aids in IAAF-sanctioned events. Oskar Pistorius, a bilateral amputee and track runner using a carbon fibre prosthesis, claimed the right to compete in IAAF track events along ‘able-bodied’ athletes. The IAAF refused his participation, relying on a newly introduced rule prohibiting use of technical devices that give an athlete an advantage over other competitors, more specifically:

Use of any technical device that incorporates springs, wheels or any other element that provides the user with an advantage over another athlete not using such a device” (IAAF Competition Rule 144.2(e), at the time).[2]

As a result, Oskar Pistorius brought the matter before CAS. Though the rule contained no explicit allocation of the burden of proof, it was common ground among the parties that the burden of proof was on the IAAF to prove the existence of an ‘advantage’.[3] As regards the standard of proof, the CAS panel determined that it would apply the ‘balance of probabilities’ standard, since it did not regard the issue as a disciplinary one that would mandate a higher standard, such as ‘comfortable satisfaction’.[4] Though Pistorius underwent a series of performance tests supervised by the Sports University in Cologne, Germany, the CAS panel deemed the scientific evidence produced inconclusive. Specifically, to the panel, the evidence did not allow for a sufficiently robust conclusion that Pistorius enjoyed an overall net advantage over able-bodied competitors. Thus, Pistorius should not be prevented from competing at IAAF-sanctioned events.

Shortly after the Pistorius award, the IAAF amended its Competition Rules with a view to having the burden of proof shifted to the athlete claiming the right to compete with mechanical aids. Since then, the rule – in its version still applicable in the Leeper matter (the rule is enshrined today in the World Athletics Technical Rules, Rule 6.3.4) – has provided that receiving assistance during an event is not allowed, including:

The use of any mechanical aid, unless the athlete can establish on the balance of probabilities that the use of an aid would not provide him with an overall competitive advantage over an athlete not using such aid” (Rule 144.3(d); emphasis added).

That shift of burden quickly showed very tangible effects. In 2016, Markus Rehm, a German long jumper and single-leg amputee, using the same type of prosthesis, set out on an attempt to achieve qualification for the Rio Olympic Games. Studies were again conducted at the Sports University in Cologne that had already produced the expert report for Oskar Pistorius. The research conclusions were that it was impossible to tell with certainty whether the prosthesis conferred Markus Rehm an overall advantage in long jump. However, due to the regulatory amendment, this inconclusiveness now weighed against the athlete. After an IAAF June 2016 meeting in which no vote was finally declared on the issue, IAAF President Sebastian Coe commented: “Rehm still has to prove that the prosthetic doesn’t give him an unfair advantage and he has not been able to show that”.

To the best of the author’s knowledge, Markus Rehm never took formal legal action against the sports authorities and finally renounced seeking a selection to the Rio Olympic Games. The discussion announced in Summer 2016 with the IAAF never appears to have produced outcomes either, so that the new version of the rules and its effects had not been subject to the scrutiny of a judicial body so far.

More than ten years after Oskar Pistorius obtained the right to compete under the former IAAF rules, Blake Leeper – a bilateral amputee track runner specialising in the 400m - applied in July 2019 to the IAAF for a ruling that the prothesis he uses in pursuit of his qualification for the 2020 Olympic Games is allowable under IAAF Rule 144.3(d).[5] In February 2019, after various exchanges between the parties and upon Mr Leeper submitting the results of various tests, the IAAF denied his application.[6] Mr Leeper appealed the IAAF decision to the CAS.


2.     The reasoning of the CAS panel in the Blake Leeper award

In its analysis of Blake Leeper’s case, the CAS panel proceeded in three steps:

  • i.) determining the proper construction of IAAF Rule 144.3(d);
  • ii.) assessing validity and lawfulness of the provision that imposes the burden on the athlete to establish absence of an overall competitive advantage; and
  • iii.) considering the findings on the previous points, deciding whether Mr Leeper should in casu be entitled to compete at IAAF-sanctioned events using his prosthesis.[7]

In short, after defining an appropriate ‘test’ for presence (or absence) of an overall competitive advantage, the CAS panel found that it was not admissible for the rule to place on the athlete the burden to establish the factual prerequisites for such test. The CAS panel then reworded the rule by ‘deleting’ the parts related to the burden of proof, thus in effect shifting back the burden to the IAAF as per the former version of the rule applicable in the Pistorius matter. Nevertheless, considering the evidence on the record, the CAS panel found that in the particular matter the IAAF had met such burden, so that Mr Leeper could not be allowed to compete at IAAF-sanctioned events with his current prostheses.

The main legal issue at stake in the award was the validity of a provision that places the burden on the athlete to establish an absence of overall advantage achieved through the use of a mechanical aid.

The award contains some noteworthy reasoning regarding the parties’ respective burden of proof with respect to the general validity of rules enshrined in sports regulations. The CAS panel proceeded along the lines adopted in previous cases in which a discrimination was invoked: referring explicitly to the proceedings involving Dutee Chand and Semenya Caster,[8] the panel described the analysis as a two-step one:

  • i.) “the party seeking to challenge an allegedly discriminatory regulation bears the burden of the establishing that the rule discriminates on the basis of a protected ground”;
  • ii.) if so: “the burden of proof shifted to the IAAF to establish that the regulation was necessary, reasonable and proportionate”.[9]

Regarding the rule at stake, the panel found that, while “neutral on its face (in the sense that it applies to all athletes equally and irrespective of any disability), the practical effect of the Rules is likely to be significantly greater for disabled athletes than able-bodied athletes.”[10] Thus, the rule was characterised as “indirectly discriminatory”,[11] so that the panel proceeded to assess whether the IAAF had demonstrated that the provision on the burden of proof pursues a legitimate objective and is proportionate. Turning to this central issue, the CAS panels analysed the following elements:

In a first step, the CAS panel supported the argument whereby

an international sports governing body such as the IAAF is legitimately entitled to take the view that fairness requires that the outcome of competitive athletics should be determined by natural physical talent, training and effort, and that athletes should not  be able to use artificial technology during competitions in a way that provides them with an overall advantage over athletes who are not using such technology. The Panel considers that this is particularly so where (as here) the mechanical aid is one that most athletes would not, in practice, be able to utilise” (emphasis added).[12]

On the other hand, the panel declared itself mindful that disabled athlete such as Blake Leeper would be “unable to participate at all in IAAF-sanctioned events in circumstances that would enable their results to be ranked alongside their fellow able-bodied competitors. A rule which was specifically designed to prevent disabled athletes from competing in IAAF-sanctioned events could not be said to pursue a legitimate interest” (emphasis in the award).

While deploring that the IAAF seemed to have given little weight to facilitating participation of disabled athletes (“it is apparent to the Panel that the rights and legitimate interests of disabled athletes were, at best, a secondary consideration in the IAAF’s regulatory decision-making”),[13] the arbitrators declared themselves nevertheless satisfied on balance that the rule was intended to pursue the legitimate objective of ensuring the fairness and integrity of competitive athletics.

On the issue of proportionality, the panel started by acknowledging that there is a potential at least that prosthetic aid could enable disabled athletes to run faster than if they had fully intact biological legs. The panel then reviewed the arguments specifically put forward by the IAAF:

  • i.) The first principled argument was that an exception to the ‘normal’ eligibility requirements justifies placing a burden on athletes to establish “granting the exception sought will not undermine the objectives on which that rules is based”.[14] The CAS panel refused the analogy claimed by the IAAF to the ‘precautionary principle’, but accepted that there was a valid analogy to some extent to the TUE regime, with the reservation that TUE regulations were not designed specifically with disabled athletes in mind, and thus there was nothing to suggest that the TUE regulations have any disparate impact upon disabled athletes;
  • ii.) The second argument, of a practical nature, was that athletes are in a better position to provide the evidence regarding any advantages and disadvantages they derive from the use of the mechanical aid. The panel did not consider this argument “a particularly persuasive reason”,[15] given that the IAAF could obtain at least evidence regarding performance in competitive races, and an athlete who would refuse without justification to give data to the IAAF could see adverse inferences drawn against him or her.

The panel continued that there were, on the other hand, a number of factors pleading against the burden of proof provision being a proportionate solution; most notably, the “onerous practical burden” that the rule imposes upon disabled athletes:

Such an individual is required, in effect, to prove a negative: namely, that they derive no overall competitive advantage from having prosthetic rather than biological limbs. As the materials presented by the parties in this appeal amply demonstrates, the factual and scientific enquiries necessarily entailed by that requirement are multifaceted and complex”.[16]

In addition, the CAS panel emphasised that the IAAF failed to provide for a “clear, accessible and structured process that must be followed” by the disabled athletes to obtain a determination on their participation.[17] Finally, the panel considered that “when dealing with a rule that has a substantial disparate impact on disabled athletes, it is neither necessary nor proportionate for any doubt to be resolved against the disabled athlete”.[18]

Based on the reasons stated above, the panel concluded that the rule was to be declared unlawful and invalid with respect to its allocation of the burden of proof. As a result, the CAS panel declared the part-provision of the rule related to the burden of proof to be “deemed deleted”,[19] rewording the rule as unauthorised assistance including

The use of any mechanical aid, unless [text deleted] on the balance of probabilities [text deleted] the use of an aid would not provide them with an overall competitive advantage over an athlete not using such an aid”.[20]

While this article does not further elaborate on the discrimination question, it is noteworthy that back in 2008, the panel in the Oskar Pistorius matter dismissed the athlete’s argument of unlawful discrimination after a summary assessment, based on the fact that: “disability laws only require that an athlete such as Mr Pistorius be permitted to compete on the same footing as others”, adding that the issue before the panel was precisely to decide whether the athlete was competing on an equal basis using his prostheses.[21] The panel in Pistorius thus focused almost entirely on whether Pistorius, in casu, met the requirements set up by the rule in place, without questioning the rule itself. The fact that a legal submission which could be dismissed in a few paragraphs as barely relevant in 2008 was considered worthy of an in-depth discussion spanning several pages in 2020 does point to a heightened awareness of issues of discrimination and willingness of CAS panels to deal with these issues, which represents an encouraging signal for the sports community and advocates of human rights in sports.


3.     Defining the proper test for an ‘overall advantage’

The panel spent considerable time on the interpretation of IAAF Rule 144.3, pondering on the appropriate test for evaluating an overall performance advantage, especially ‘who’ and ‘what’ to use as a comparator for the athlete’s performance. The panel considered that this determination must be guided by the “overarching object and purpose of the Rule, and by the need to ensure that the Rule is not interpreted in a way that gives rise to consequences which are absurd or unworkable”.[22]

The panel thus stressed that it would lead to absurd results to use as a comparator either only the very best abled-bodied athletes in the world, or the disabled athlete himself without his mechanical aids. It would be equally unworkable, according to the panel, to look at the likely performance of a different (real or hypothetical) able-bodied athlete, “unless there was a principled, objective and consistent basis for determining the identity/attributes of that able-bodied comparator”.[23]

Having considered and rejected other constructions, the CAS panel concluded that

The only logical, principled and workable construction of the Rule is one that, in the case of disabled athletes who use a mechanical aid to overcome a disability, requires a comparison to be undertaken between the athlete’s likely athletic performance when using the mechanical aid and their likely athletic performance had they not had the disability which necessitates the use of that aid”.[24]

A disabled athlete who uses a mechanical aid which does no more than offset the disadvantage caused by their disability cannot be said to have an “overall competitive advantage” over a non-disabled athlete who is not using such an aid”.[25]

The test thus differs from the one conducted by the CAS panel in the Pistorius matter, that sought to identify whether the device gave Oskar Pistorius an advantage “over other athlete not using the device”.[26] In the case of Pistorius, actual comparative tests had been performed by Cologne using a control group of able-bodied athletes, and in fact the wording of the rule at the time explicitly referred to comparison to “another athlete not using such a device” (emphasis added, see Section 2 above). These selection of this control group was not assessed in detail in the Pistorius award, possibly because the panel found that the scientific experts had not been asked by the IAAF to assess the relevant question, i.e. whether the athlete enjoyed an ‘overall net advantage’ – including all advantage and disadvantages – over able-bodied athletes.

Though possibly the most ‘pragmatic’ interpretation of the rule and one adapted to the specificities of the case, the construction chosen by the panel in the Leeper award creates a standard for mechanical aids that is very focused on the situation of disabled athletes, and which will have to be further exemplified and circumscribed in future. The panel did insist that there is an “obvious desirability of a rule that is specifically tailored to the use of prosthetic aids by athletes”,[27] and criticized the IAAF’s choice “to shoehorn such athletes into a wider rule concerned with the use of mechanical aids in general”.[28] In a press release following the award, the IAAF (newly, World Athletics) took note of the panel’s findings and announced that it will work on reviewing its rules.

In fact, a redrafting would be desirable just from a perspective of legal predictability and regulatory technique. The rule as reworded through deletion by the CAS panel remains unsatisfactory in its design: the rule sets positive prerequisites (‘use of a mechanical aid’), and a negative prerequisite (‘unless no overall competitive advantage exists’). Negative prerequisites of this kind are generally interpreted as signifying an exception to the general rule, meaning that the burden of proof is on the party seeking to claim the benefit of such exception.[29] A good illustration is the way CAS panels have placed the burden on the athlete to show ‘compelling justification’ for refusing to submit to testing in anti-doping matters, even in the absence of an explicit attribution of burden of proof, simply based on the rule’s structure.[30] Redrafting the rule in such manner that its construction positively shows that the burden is on the sports governing body to show the presence of an overall advantage would almost inevitably suppose a separate rule to be created for mechanical aid used by disabled athletes.

Another difficulty is that the test as designed by the CAS panel results in a comparison that is in essence hypothetical – if not metaphysical –, and may thus prove difficult to translate into scientific terms amenable to testing: unlike studies that can actually measure performance against other ‘real’ competitors, there is no straightforward empirical way to compare an athlete with his fictional able-bodied ‘self’. In fact, in the case of Blake Leeper, the analysis conducted proved a largely non-empirical one and was facilitated by the panel choosing a single criterion (i.e. running height) that required no empirical assessment of performance on the track (see Section 5 below).

Beyond the technical issues above, it is hard to imagine how the test proposed by the CAS panel could find application to other instances of mechanical aids. ‘Disadvantages’ that originate in natural physical traits are commonplace among athletes (some may be at a natural disadvantage due to their smaller-than-average size, due to their body proportions, due to their muscle fibres or cardiovascular characteristics, etc.). It would seem unimaginable that mechanical aids be in future declared admissible as long as they just compensate such physical ‘disadvantage’ that an athlete would have compared to an average opponent.

The CAS panel in the Pistorius matter had insisted that “disability laws only require that an athlete such as Mr Pistorius be permitted to compete on the same footing as others”.[31] One may wonder whether the panel in Leeper did not implicitly go a step beyond that objective: insofar as it defines the same (fictional) athlete himself, without the disadvantage derived from his disability, as the upper benchmark to limit performance enhancement through mechanical aid, the panel’s reasoning amounts to creating a right to compensate for natural disadvantages that able-bodied athletes do not enjoy.

This position presupposes in addition the existence of a difference of nature between a normal ‘below average’ athlete on the one hand, and an athlete with a disability or other physical condition, on the other hand. In this respect also, the scope of the panel’s ruling would have to be better defined. In particular, the panel never went into the category of the ‘disabled athlete’ who should benefit from the right to offset their disadvantage in comparison to their hypothetical able-bodied self. Should only athletes who fulfil the conditions of an ‘Eligible Impairment’ for purposes of participation in Paralympic sports – including Paralympic Athletics – be authorised to compensate their disadvantage? Should certain other, non-eligible impairments and medical conditions also qualify, and according to what criteria? There will inevitably be value judgements involved in distinguishing between a disadvantage that represents a genuine disability creating a right to compensation, versus a disadvantage that results merely in a sub-standard physical ability that is part of an individual’s characteristics and which simply makes the athlete ill-suited for (specific) sports.


4.     Expectations on the scientific evidence to assess the overall advantage

Various arguments discussed by the panel demonstrate sympathy for disabled athletes, including recognition of the insurmountable hurdle that a burden of proof on scientific issues may constitute for such athletes. The panel took the view that an athlete could not be reasonably expected to carry such a heavy burden. These expressions of sympathy could be of relevance for cases in other areas of sports regulations, highlighted in Section 6 below.

Predictably, in all but the exceptional case, the outcome of studies would result in an inconclusive state of evidence. In this constellation, the burden of proof becomes the main – if not the sole – determinant of the outcome: it decides which party carries the risk of scientific uncertainty. In certain situations, what is formally a rebuttable presumption may thus turn de facto into an irrebuttable one.[32]

As mentioned (see Section 2 above), in both the case of Oskar Pistorius and Markus Rehm, studies of the athlete’s performances did not allow for a clear-cut conclusion. The two cases were fairly similar in terms of scientific assessment. The difference was a purely legal one, namely: under the new version of the rule enacted by the IAAF and applied to Markus Rehm, an inconclusive state of scientific evidence had to lead to decide against the athlete’s participation.[33]

In the matter of Blake Leeper, the panel reversed the effects of the amendment made by the IAAF after the Pistorius award: this means that disabled athlete are now admitted to participate in IAAF-sanctioned events with mechanical aids, in all but the exceptional situation in which the scientific evidence could clearly show an overall advantage.

The perhaps most surprising element of the case is that the Leeper matter turned out to be one of these ‘exceptional’ cases, and the manner in which the CAS panel reached its conclusion. When applying the test to Blake Leeper, the evidentiary burden on the IAAF indeed appeared much lighter than what the panel described as the enquiries that athletes would have to conduct in order to even stand a chance of discharging their burden.

When weighing in on the heaviness of the burden for athletes, the CAS panel had stressed that assessing whether a mechanical aid confers an overall competitive advantage would suppose “obtaining, analysing and presenting […] complex scientific data”, which “is likely to be challenging, expensive and time consuming”.[34]

The arbitrators listed a number of enquiries that such a determination would entail:

it will typically be necessary to obtain, analyse and present detailed and highly technical scientific evidence concerning metrics such as the biomechanics, acceleration, maximum velocity, sprint endurance, curve-running, running economy and aerobic capacity (and, potentially, other metrics too). It will also be necessary to establish (insofar as this is scientifically possible) how each of those metrics would differ if the individual in question had biological legs rather than prosthetic limbs, and how those actual and hypothetical metrics compare to the other able-bodied athletes who compete in the same event”.[35]

Admittedly, the assessment was facilitated by the fact that Blake Leeper had actually undergone a series of tests as part of his seeking to discharge his burden of proof, so that the IAAF had the benefit of the resulting data. The arbitrators themselves noted that it would be rather unusual for a party to be able to discharge a burden of proof without having proactively submitted any scientific evidence of their own.[36]  Upon closer scrutiny, however, the results of these tests do not even appear to have been decisive for the panel’s ruling. Ultimately, the assessment was reduced to one single question, with two sub-questions: i.) does Mr Leeper run ‘unnaturally tall’ on his prosthesis, and ii.) does this give him any performance advantage?

The first question was resolved through the so-called MASH (‘Maximum Allowable Standing Height’) rule: a formula applied in Paralympic competitions which allows for an estimation of the maximum height that a Paralympic runner is allowed to run at on his prostheses in the context of Paralympic sports.[37] Blake Leeper’s prostheses placed him well above (i.e. by 15cm) the MASH height so determined. The panel treated this as indication that Leeper runs at a height substantially taller “than his height if he had intact biological legs, with a generous margin of appreciation for the diverse shapes and sizes of the human body”.[38] The second question was equally resolved by general biomechanical considerations: the panel found that the empirical evidence produced by the athlete was inconclusive on this point, and the panel was willing to follow the IAAF’s experts that “there is a direct relationship between leg length and running speed”.[39]

Thus, using two simple mathematical formulas and without truly exploiting the results of the tests conducted on Leeper, the panel was able to conclude that:

by virtue of the fact that he uses RSPs that enable him to run at a height that is several inches taller than his maximum possible height if he had intact biological legs, Mr Leeper is able to run the 400m event in a time that is several seconds faster than the fastest time he would have been able to achieve with intact biological legs”.[40]

In effect, the CAS panel was thus able to bypass almost entirely the findings of the studies conducted by and on the athlete – after brushing aside the peer-reviewed study on the record – to focus exclusively on the opinion of the IAAF experts rooted in the general biomechanics of running. It is unlikely that a CAS panel would easily be able to reproduce that straightforward a benchmark in future cases with different disabilities. Also, it could prove important to monitor in practice what expectations panels will put on the IAAF in individual cases, and what expectations it will place on athletes in terms of duty to cooperate to the evidentiary process, to ensure that the allocation of the burden of proof will not be undermined by its application in practice.


5.     Impact of the award beyond mechanical aid

A shift in the burden of proof is a common tool used in sports regulations for issues that require complex scientific proof: for example, when a CAS panel in the Veerpalu v. FIS matter determined that it was upon the anti-doping organisation to establish the validity of its analytical methods and decision limits used, the prompt reaction in the review process of the World Anti-Doping Code (‘WADA Code’) ongoing at the time was to introduce a provision shifting that burden to the athlete (Article 3.2.1 WADA Code).[41] Other well-known reversals of this kind in anti-doping matters include establishing a departure from applicable testing or analytical procedures (Article 3.2.2/3.2.3 WADA Code), or the presumption resulting from the report of an adverse analytical finding, which requires the athlete to adduce evidence regarding the manner in which a prohibited substance came to enter his or her body in order to establish absence of or low fault. [42]

The parallels are even more striking with the WADA system for obtaining Therapeutic Use Exemptions (‘TUE’). The WADA International Standard for Therapeutic Use Exemptions (‘ISTUE’) provide that athletes have to establish the requirements for obtaining a TUE, by a balance of probabilities, one of these requirements being:

The Therapeutic Use of the Prohibited Substance or Prohibited Method is highly unlikely to produce any additional enhancement of performance beyond what might be anticipated by a return to the Athlete’s normal state of health following the treatment of the acute or chronic medical condition” (ISTUE 4.1(b)).

In the Leeper matter, the panel accepted that there was a “certain analogy to be drawn” with TUE regulations. However, the panel appeared to consider that there was nevertheless a material difference between the situation of disabled athlete using mechanical aids and athlete requiring a TUE:

the regulations governing TUEs were not specifically enacted with disabled athletes in mind. Unlike the Rule under consideration here, there is nothing to suggest that the TUE regulations have any disparate impact upon disabled athletes”.[43]

Assuming there was an intent on part of the panel to practice distinguishing here, the rationale for such distinguishing remains obscure. It suggests that athletes suffering from permanent health conditions would be somehow less worthy of legal protection than disabled athletes, or better harmed with financial and expert resources. Whether disabled athletes are affected specifically by the TUE regulations, or other athletes with acute or chronic health conditions, does not seem to bear any relevance for the impact of such a regulation on the affected athletes, and hence, for the proportionality of the burden of proof.

On the contrary, the principled and practical rationale that led the panel to find a lack of realistic prospects for athletes to discharge that burden would apply equally in TUE cases. As highlighted in connection with the case ISSF v. WADA,[44] which concerned a young shooter who proved unable to establish that the medically necessary beta-blockers did not enhance her performances, this aspect of the TUE requirements raises considerable issues. First, it equally supposes proof of a negative, which ought to lead at least to the recognition of a situation of ‘evidence necessity’ (Beweisnotstand), similar to the one applied by the CAS panel in the WADA & UCI v Contador & RFEC matter, to ease the burden on the athlete. Second, establishing performance enhancement associated with use of a substance is an onerous and often impracticable task, and a burden that WADA itself refuses to carry, since the WADA Code claims that performance enhancing effects cannot be challenged in court. It has been repeatedly emphasised in WADA circles that proving performance enhancement would prove unethical and impractical in many cases.

Specifically, this extract from the Leeper award essentially describes the situation in which many athletes will find themselves when faced with anti-doping proceedings:

many, if not most, disabled athletes in that position will not have immediate access to experts with the requisite expertise or to appropriate testing and research facilities that enable such data to be gathered for analysis. […] there is a significant risk that the financial cost of obtaining the relevant data and expert analysis will be prohibitive for many disabled athletes, and therefore they will be unable to attempt to meet the burden imposed by the Rule […]”.[45]

For many athletes, challenging the validity of an analytical method or decision limit, showing entitlement to a TUE, or even just demonstrating how a substance ended up in their sample in order to establish their absence of fault, will plainly never be a realistic option. As the panel stressed in the Leeper case, in certain situations both fairness and access to evidence could be adequately accounted for, on a case-by-case basis, by drawing adverse inferences against an athlete who would refuse to cooperate with anti-doping organisations without legitimate justification.


6. A Never Ending Story

The outcome of Blake Leeper’s battle, and the relative ease with which the CAS panel reached its decision considering the difficulty of its task, must be viewed as rooted in the circumstances of the case: a clear-cut case of an athlete with a disability (bilateral amputee), a fictional able-bodied counterpart that was relatively easy to imagine conceptually (the same individual with biological legs), and - probably also - an athlete who had chosen mechanical aids that made him taller than he would ever have been with biological limbs. One may wonder how the same assessment would concretise in other contexts and how broadly this case law would be transposable to other cases of mechanical aid, even involving other categories of disabled athletes. The award made thus be programmed to remain an outlier.

The panel was able to come up with a simple operational criterion, i.e. comparing the height of the athlete when on his prosthesis to his maximum natural height, and applying a proportionality relationship whereby the height at which the athlete runs conditions the length of his stride and thus his speed. In fact, to put it somewhat provocatively, following through on the solution used by the panel would render athletic competitions meaningless, as it would be sufficient to measure each athlete’s legs to predict the outcome of a race.

In a broader perspective, the ruling in the Blake Leeper matter no doubt represents a step toward inclusiveness of athletics and sports competitions in general. The CAS panel was adamant that sports governing bodies must not adopt rules that discriminate – directly or indirectly – against athletes with a disability, or at least not without very robust justification. The CAS panel also pulled the brakes on what has become common practice when sports governing bodies stumble on issues that may be affected by irreducible uncertainty in science, or that would require significant evidentiary efforts: transferring these efforts onto the athletes by attempting to shift the burden of proof in their rules. The paradox is that the arbitrators then appeared very generous in assessing in casu the scientific justification adduced by the IAAF to support its decision, in a way that did not correlate with the heaviness of the evidentiary burden from which the panel had just resolved to save the athlete.

Perhaps most importantly, the series of cases from Pistorius to Leeper highlights that the burden of proof is a policy choice first of all, if not exclusively. In situations that are characterized by scientific complexity and evidentiary conundrums, the burden of proof determines the outcome of individual cases as effectively as if the parties were confronted with an irrebuttable presumption or legal fiction. The burden of proof can thus be said to reflect the “institutional default” behind the regulator’s or (here) the arbitrators’ value framework.[46] This makes it all the more important that the administration of such burden of proof in practice is not dealt with too lightly by panels in individual matters.

In this regard, the series also forces us to recognise that there is no way a level playing field can be defined through science, or at least not through science alone. The outcome reached by the panel in Leeper is based on a moral choice of what a ‘fair’ competition should look like and on ideals of inclusiveness and non-discrimination. The IAAF and the panel in Leeper invoked repeatedly in the award as the rule’s legitimate aim that the outcomes of competitions be determined by “competitors’ natural talent, training and effort”, as opposed to aids that confer an “artificial” competitive advantage.[47] However, the solution reached by the CAS arbitrators cannot be reconciled with the legitimate aim they relied on, unless one considers that the disabled athlete’s ‘natural’ state is his hypothetical self without the disability. Unless one treats disability as unnatural, any mechanical aid used by a disabled athlete to allow him to complete a 400m is necessarily ‘artificial’ to use the language of the CAS. Here again, the panel’s reasoning – though based at first sight on the MASH formula and objective biomechanical principles – is in reality deeply entwined with what the panel envisioned as a ‘normal’ – perhaps rather than ‘natural’ – human body, thus arguably a normative rather than biological standard.

This means that it would be unreasonable to place all expectations on science to resolve the societal dilemmas that inclusiveness in sport creates. Instead, we are bound to continue to feel our way forward through all conflicting interests and values at stake, continuously renegotiating their respective importance. In fact, in its press release acknowledging the CAS award, the IAAF mentioned newly framed claims by Blake Leeper’s legal team that the MASH rule relies on ‘racist’ foundations. The IAAF stressed – almost preemptively – that there is no basis in evidence to challenge the rule, and certainly not to assume that the 15cm disparity in height could be due to “racial differences in body dimensions”. The new CAS precedent just established may thus prove vulnerable to challenges based on other discrimination grounds, which are likely to trigger equally intractable scientific questions.

As the panel in the case of Oskar Pistorius concluded, noting that the IAAF would have to assess each athlete’s situation in the future on a case-by-case basis: “However, if it does create an additional burden, it must be viewed as just one of the challenges of 21st Century life”.[48] Apparently, the challenge has only just started.


[1] CAS 2020/A/6807, Leeper v. IAAF, 23 October 2020. The IAAF has been renamed World Athletics. However, since the award still uses the term ‘IAAF’, this article will also do so for convenience.

[2] CAS 2008/A/1480, Pistorius v IAAF, 16 May 2008, p. 3.

[3] CAS award Pistorius, para. 38.

[4] CAS award Pistorius, para. 39.

[5] CAS award Leeper, para. 5.

[6] CAS award Leeper, para. 6.

[7] CAS award Leeper, para. 291.

[8] In fact, this is not entirely accurate since in the Dutee Chand matter, the panel considered the burden of proof was on the athlete when it comes to the scientific validity of the regulation, and the athlete did not object to this burden. For an analysis, Viret M & Wisnosky E (2016), Comment of CAS 2014/A/3759, Chand v. AFI & IAAF, 24 July 2015, in (Duval & Rigozzi (eds.)), Yearbook of International Sports Arbitration, The Hague, 235-274.

[9] CAS award Leeper, para. 315.

[10] CAS award Leeper, para. 318.

[11] CAS award Leeper, para. 319.

[12] CAS award Leeper, para. 325.

[13] CAS award Leeper, para. 330.

[14] CAS award Leeper, para. 340.

[15] CAS award Leeper, para. 342.

[16] CAS award Leeper, para. 344.

[17] CAS award Leeper, para. 350.

[18] CAS award Leeper, para. 356.

[19] CAS award Leeper, para. 361.

[20] CAS award Leeper, para. 361.

[21] CAS award Pistorius, para. 29.

[22] CAS award Leeper, para. 306.

[23] CAS award Leeper, para. 309.

[24] CAS award Leeper, para. 88.

[25] CAS award Leeper, para. 310.

[26] CAS award Pistorius, para. 47.

[27] CAS award Leeper, para. 300.

[28] CAS award Leeper, para. 331.

[29] Viret M (2016), Evidence in Anti-Doping at the Intersection of Science and Law, The Hague, p. 78.

[30] CAS 2019/A/6148, WADA v. Sun Yang & FINA, para. 336.

[31] CAS award Pistorius, para. 29.

[32] Viret M (2016), Evidence in Anti-Doping at the Intersection of Science and Law, The Hague, p. 662.

[33] For a similar analysis, see Pielke R (2016), The Edge, Berkeley, pp 262-263.

[34] CAS award Leeper, para. 345.

[35] CAS award Leeper, para. 344.

[36] CAS award Leeper, para. 365.

[37] See for a discussion CAS award Leeper, para. 67 et seq.

[38] CAS award Leeper, para. 379.

[39] CAS award Leeper, para. 389.

[40] CAS award Leeper, para. 390.

[41] Viret M & Wisnosky E (2016), The Validity of Analytical Science in Anti-Doping – A Scientific and Legal Challenge, in (Duval & Rigozzi (eds.)), Yearbook of International Sports Arbitration, The Hague, 39-72, p. 50.

[42] Viret M (2016), Evidence in Anti-Doping at the Intersection of Science and Law, The Hague, p. 662.

[43] CAS award Leeper, para. 341.

[44] Rigozzi A/ Viret M/ Wisnosky E, The ISSF v. WADA CAS Award: Another Therapeutic Use Exemption Request for Beta Blockers Shot Down

[45] CAS award Leeper, para. 347.

[46] Pielke R, The Blade Runner and the Burden of Proof.

[47] CAS award Leeper, para. 332.

[48] CAS award Pistorius, para. 56.

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