Contaminated supplements and strict liability: the minefield of non-deliberate doping

This article was originally published in Issue 1 of ‘Read the Game’, a newsletter written by members of the University of Law (Moorgate)’s Sports Law Society.

Contamination and strict liability

On the face of it, staying on the right side of anti-doping rules seems a simple task for any well-meaning clean athlete: don’t take any banned substances and don’t miss any anti-doping tests. However, even those who have no intention to cheat are becoming increasingly fearful of being caught out. Sensitive tests can reveal trace amounts of banned substances that may have been contained in a legal supplement contaminated with the banned substance during production, opening the door to cases of ‘non-deliberate doping’. The rise of contamination cases in sports like athletics and tennis has led to increased athlete fears over supplement use. The extremes of this were recently emphasised by former US Open Champion Emma Raducanu, who expressed fears over using an antiseptic spray in case it was contaminated.[1]

Regardless of their individual levels of fault, the principle of strict liability means athletes risk a ban (and a tainted legacy) if their drugs test is found to contain a banned substance, even if the athlete can prove the substance came from ingestion of a contaminated legal supplement. Strict liability is the legal principle whereby a person can be held responsible for all consequences of their actions, regardless of any intent or negligence. It is a core principle of the anti-doping system in sports, meaning that athletes are responsible for all substances found in their drug tests, regardless of whether they had any intention to cheat.

Strict liability is an essential part of the anti-doping system. Put simply, the system would be unworkable without it. This is because it is exceptionally rare for an athlete to be caught in possession of banned substances, or even administering the substance (a notable exception is Austrian cross-country skiier Max Hauke, whose hotel room was raided with the needle still in his arm).[2] Putting aside these rare cases, strict liability is therefore an essential tool for anti-doping organisations to prosecute athletes who have taken banned substances in the absence of any evidence on how or when the substances were ingested.

Rules relating to strict liability can manifest themselves in a few different outcomes when cases reach national-level anti-doping panels or the Court of Arbitration for Sport (CAS). Article 10.1.1 of the World Anti-Doping Agency (Wada) Code notes that an athlete can establish “No Fault or Negligence” for an anti-doping violation, even in the case of a positive test.[3] However, whilst establishment of “No Fault” can decrease the length of an athlete’s ban, it rarely prevents a ban entirely – strict liability rules are often used to punish athletes who have tested positive for a banned substance even without ‘intentional’ doping, as will be explored in some of the cases below.

Case studies

The list of athletes who have failed a drugs test but protested their innocence due to contaminated supplements is long. Seven recent cases are outlined in the table below. These case illustrate the complexities of the contamination issue, with varying outcomes based on perceived athlete responsibility and the strength of evidence for their contamination argument:

Athlete	Sport	Banned substance	Defence argument	Case outcome
Shelby Houlihan[4]	Athletics	Nandrolone	Consumption of a burrito containing pork offal high in nandrolone	Did not succeed in establishing that the burrito was the source of the substance, 4 year ban
Issam Asinga[5]	Athletics	GW1516	Consumption of Gatorade Recovery Gummies contaminated with the substance	Did not succeed in establishing that the Gummies were the source of the substance, 4 year ban
CJ Ujah[6]	Athletics	Ostarine and S-23	Consumption of contaminated beta alanine supplement	Established as non-intentional, 22 month ban
Jannik Sinner[7]	Tennis	Clostebol	Physio used a clostebol spray to treat a cut on his own finger, substance entered Sinner’s body through massage	Settlement between Sinner and Wada for a 3 month ban
Iga Swiatek[8]	Tennis	Trimetazidine (TMZ)	Melatonin tablets used for jetlag contaminated with TMZ	1 month ban, “No Fault” conviction
Tara Moore[9]	Tennis	Nandrolone and boldenone	Consumption of contaminated beef	Initial 2 year ban, overturned on appeal, “No Fault” found
23 Chinese athletes[10]	Swimming	Trimetazidine (TMZ)	Contamination of parts of a shared kitchen on a training camp with TMZ	Mass case of contamination, no anti-doping rule violation issued by Chinese Anti-Doping Agency (CHINADA)

For sports fans reading this who may know a little about some or all of these cases, the perceptions of innocence will differ. However, the facts are that each of the athletes mentioned has failed a drugs test and been banned as a result (with the exception of the unique case of the Chinese swimmers).

In Sinner’s case, Wada general counsel Ross Wenzel described it as “a million miles away from doping”,[11] yet a ban was still pursued in order to uphold the principle of strict liability, perhaps using Sinner as an example of why athletes must be incredibly careful about all substances that come into contact with their body. Asinga’s and Houlihan’s cases were less successful – in both instances, the Court of Arbitration for Sport (CAS) did not accept their contamination arguments after hearing the scientific evidence, and instead the full 4 year ban was issued.

The case of the Chinese swimmers is too complex to set out fully within this article (Wada’s timeline and FAQ provides an excellent explanation of the case).[12] However, it is interesting to note that CHINADA found no anti-doping rule violations despite 23 swimmers testing positive for TMZ, whereas Wada make it clear in their statement that, were the case handled by them initially, they would have likely found the athletes to have committed a “No Fault rule violation”. Wada however chose not to appeal the case, as the appeal would not have been in pursuit of a ban for any of the swimmers.

One ban length in the above table appears to stick out: CJ Ujah’s 22 month suspension despite the Athletics Integrity Unit (AIU) agreeing that the test came from consumption of a contaminated supplement. Ujah was found to have failed to take specific precautions relating to his supplements. Ujah purchased the legal supplement beta alanine from Amazon, without checking the supplement’s source in detail. This process has been made more straightforward for athletes with the ‘Informed Sport’ certification introduced in 2008.[13] Any supplement with the Informed Sport certification has been batch-tested for banned substances, meaning that professional athletes can take these supplements without fearing an inadvertent positive test. Furthemore, athletes can use the Global Drugs Reference Online (DRO) system to check the ingredients of over-the-counter medications in many countries, limiting the risk of unintentional consumption of banned substances.[14]

This process should theoretically removed the need for the contaminated supplement argument. However, as explored in the cases above, a level of nuance remains with cases like those relating to contaminated meat (Houlihan; Moore) or the failure to use Informed Sport supplements.

Is the status quo unfair?

The major issue many athletes and fans take with the principle of strict liability is a fear that it brings an inherent unfairness to anti-doping. Sinner’s 3 month ban has brought a cloud over his head that will last for his entire career, undoubtedly tainting his legacy to those who read the headlines of his ban but do not look beyond them to read that even Wada saw his case as “a million miles away from doping”.

On the flip-side, contamination cases are undoubtedly muddying the water of anti-doping. They are creating fear for clean athletes, whilst simultaneously providing convenient defence arguments for athletes that are deliberately doping. The job of national anti-doping organisations, sport specific bodies like the AIU and International Tennis Integrity Agency (ITIA), and Wada are only becoming more difficult as these cases become more contentious.

What does the future look like?

As the medicalisation of sport develops and athletes go on to look for those one percent gains through legal supplements, it appears likely that these issues will only worsen. These concerns have been noted by Wada, which has recently formed the ‘Working Group on Contaminations’ (WGC) of six international lawyers to “conduct a global review on sources of contamination” and “provide guidance and recommendations to the WADA Executive Committee on potential improvements of the anti-doping regulations and practice to further take into account the risk of such contaminations while maintaining an efficient anti-doping system”.[15] The WGC follows on from Wada’s Taskforce on Unintentional Doping (TUD) which was launched in January 2024.[16]

The Wada Code is updated every six years, and the 2027 edition is expected to lead to a key change in how many of the cases discussed in this article are decided. Athletes who fail tests but are determined to have “no fault” can be punished with anything from a reprimand to a 2 year ban, meaning athletes like Sinner and Swiatek may not have been suspended under the new Code.[17]

Ultimately, contamination and strict liability is an immensely complicated aspect of anti-doping which has been subject to growing concerns and controversies in recent years. Unless significant developments can come out of Wada’s WGC and TUD, in the coming years we can expect to see more positive tests that are blamed on contamination, more drawn out legal battles, and more uncertainty amongst fans as to who is doping and what to believe.

References:

[1] https://www.theguardian.com/sport/2025/jan/10/raducanu-turns-down-insect-bite-treatment-over-doping-fears-in-australia

[2] https://www.tntsports.co.uk/cross-country-skiing/world-championships/2018-2019/cross-country-skier-max-hauke-caught-on-camera-doping-during-raid_sto7165812/story.shtml

[3] WADA Code

[4] https://www.athleticsintegrity.org/downloads/pdfs/disciplinary-process/en/7977-Award-Reasoned-FINAL.pdf

[5] https://www.athleticsintegrity.org/downloads/pdfs/other/AIU-PRESS-RELEASE-AIU-BANS-SURINAME-S-ASINGA-FOR-FOUR-YEARS.pdf

[6] https://www.athleticsintegrity.org/downloads/pdfs/other/Press-Release-Ujah.pdf

[7] https://www.wada-ama.org/en/news/wada-agrees-case-resolution-agreement-case-jannik-sinner

[8] https://www.itia.tennis/media/mohbxjhq/2024-11-27-itia-v-swiatek-itia-decision.pdf

[9] https://www.itia.tennis/media/2yvab3yj/231221-itia-v-moore-gatica-decision-amended-redacted.pdf

[10] https://www.wada-ama.org/en/news/wada-statement-case-23-swimmers-china

[11] https://www.bbc.co.uk/sport/tennis/articles/cy5ny6lx5dqo