Expertise / Sports / Supplement and food contamination
Supplement and food contamination expert witnesses
Toxicology and pharmacology evidence on how a prohibited substance got into the athlete's body.
Request an expertThe start line on an athletics track
Most contested doping cases come down to one question: how did the substance get there? A contaminated supplement, medicine or piece of meat can explain a low-concentration finding. Proving it takes toxicology and pharmacokinetics: whether the amount found fits the athlete's account, and whether the product or food could realistically have contained the substance.
This is one of the specialisms within our sports expert witness practice.
In sports, the difference between a strong case and a weak one often comes down to whether the expert truly understands the sector. Generalist opinion rarely survives scrutiny on specialist questions, and a tribunal gives little weight to evidence that misreads how sports actually works. We focus here precisely because the issues are technical, the stakes are high, and the wrong expert is an expensive mistake.
What instructing through us looks like
Tell us the issues, the forum and your timeline. We check fit, availability and conflicts, then send a short, honest shortlist. You review CVs and speak with the expert before instructing. New to the process? See our guide on how to instruct an expert witness.
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Tell us about your supplement and food contamination matter
Describe the issues and the forum. We check fit, availability and conflicts, then come back with a short shortlist. Enquiries are confidential and create no obligation.
- Tell us the matterShare the issues, the sector and your timeline. No obligation, treated in confidence.
- We shortlistWe identify experts whose experience genuinely fits, and check availability and conflicts.
- You instructYou review CVs and speak directly with the expert before instructing on your terms.
Why contamination evidence decides the sanction
Anti-doping rules are strict liability: the presence of a prohibited substance is a violation whatever the athlete intended. Contamination matters to the sanction. To show the violation was not intentional, or that they bore no significant fault, an athlete generally has to establish how the substance entered their body, on the balance of probabilities. A plausible story is not enough; the science has to support it.
The expert's job is to test the account against the numbers: whether the concentration found, and the metabolites present, are consistent with the claimed source, the amount consumed and the timing.
What the expert will examine
- The analytical result — the concentration, the metabolites and the B-sample analysis.
- Pharmacokinetic modelling — whether a realistic dose from the suspected source, taken when the athlete says, could produce the result.
- The product itself — independent testing of the supplement or medicine, ideally the opened container and a sealed one from the same batch.
- Diet and travel — meals, where the meat came from, and whether the country has a record of contamination with the substance.
- Hair analysis — in some cases, evidence of a single exposure rather than repeated use.
Keep every opened supplement and medicine container, with its batch number. Without the actual product, contamination is very hard to prove, however plausible it is.
What the CAS awards show
Contamination runs through the doping awards on the CAS recent decisions page. In CAS 2024/A/10298 (ITIA v Tara Moore) the player relied on meat contamination supported by reports from a pharmacokinetics expert. In CAS 2024/A/10647 (WADA v UKAD and Banks) a toxicologist concluded the findings were consistent with contamination. In CAS 2024/A/10655 (WADA v JADA and Toyoda), WADA's expert evidence was that meat contamination was highly improbable. And in CAS 2026/A/12149 (Pellegrini), the panel relied on an uncontradicted expert opinion that the concentration found was compatible with the topical application the athlete described.
The lesson is consistent: specific, uncontradicted expert evidence carries great weight, and experts who stray outside their field lose it. In the Toyoda case the athlete's expert accepted that he was not an expert on the effects of the substance in question.
Choosing the expert
Look for a toxicologist or clinical pharmacologist with anti-doping laboratory experience who can do the pharmacokinetic work and explain it simply. If the product needs testing, use an accredited laboratory with an unbroken chain of custody, or the result may be challenged.
Key authorities and further reading
- WADA Prohibited List — substances prohibited in and out of competition
- UK Anti-Doping: supplements — guidance on supplement risk for athletes
- Informed Sport — batch-tested supplement certification
- CAS: recent decisions — the published awards cited on this page
FAQ
Common questions
What does a supplement and food contamination expert witness do?
They give independent, objective opinion to a court or tribunal on supplement and food contamination issues within sports, with an overriding duty to the court under CPR Part 35. The opinion usually takes the form of a written report and, where required, oral evidence.
When should I instruct a supplement and food contamination expert?
As soon as the issues are clear. Early instruction helps you test the strengths and weaknesses of the case, scope the evidence proportionately and avoid a rushed report against a deadline.
How do you select experts for supplement and food contamination matters?
On substance: relevant qualifications, genuine sports experience and an understanding of an expert's duties in litigation and arbitration. Where an expert has limited experience of giving evidence, we say so.
Is a low concentration enough to prove contamination?
No. A low concentration is consistent with contamination but does not prove it. The athlete usually has to identify the source and show, with expert evidence, that it explains the amount found.
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