Expertise / Sports / Athlete Biological Passport (ABP)
Athlete Biological Passport (ABP) expert witnesses
Haematology and anti-doping science evidence for biological passport cases.
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A biological passport case has no positive test. The anti-doping organisation relies on a pattern in the athlete's blood or steroid profile, and on a panel of experts who say that pattern is likely to come from doping. The defence turns on whether there is a credible innocent explanation, and on whether the samples behind the profile were collected, stored and analysed reliably.
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 athlete biological passport (ABP) 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.
What these cases actually turn on
The Athlete Biological Passport follows markers in an athlete's samples over time. The haematological module tracks values such as haemoglobin concentration and reticulocytes; the steroidal module tracks ratios such as testosterone to epitestosterone. A statistical model flags results outside the athlete's expected range, and a panel of independent experts reviews the profile. If the panel concludes that doping is likely and other causes unlikely, the case goes ahead, usually on the panel's joint opinion.
So the dispute is about interpretation rather than detection. The tribunal has to decide whether the abnormal values are better explained by doping or by something else, and how much weight each sample deserves, including any sample whose transport or storage is in question.
What the expert will examine
- The full profile — every sample, not only the ones flagged, with the athlete's whereabouts, competitions and training camps at the time.
- Sample reliability — collection times, transport and temperature records, and the time between collection and analysis.
- Physiology and medical history — altitude, illness, hydration and plasma volume changes, blood loss or donation, and diagnosed conditions.
- The panel's reasoning — whether each alternative explanation was actually tested against the data or simply set aside.
Ask for the full documentation package as early as possible, including the transport and temperature records for each sample. An argument about a single sample's reliability needs the underlying data, not a summary.
What the CAS awards show
Several of the 536 awards on the CAS recent decisions page turn on the biological passport, among them CAS 2024/A/10704 (Kipruto v World Athletics), CAS 2023/A/10180 (World Athletics v Jeruto), CAS 2023/A/9681 (Seidl) and CAS 2023/A/9731 (Kenderesi). In each, the governing body relied on a joint opinion from its expert panel, and the athlete answered with reports from haematologists or other clinical specialists.
Two points recur. Panels give weight to experts who engage with the specific values in the profile rather than general possibilities. And they look for contemporaneous evidence behind an alternative explanation: an expert who accepts a claimed medical condition as fact, without assessing it independently, adds little.
Choosing the expert
The right expert is usually a haematologist or clinical scientist with biological passport experience, rather than a general sports physician. Check conflicts carefully: many of the most experienced passport scientists sit on the expert panels that anti-doping organisations use, which can rule them out of acting for an athlete.
Key authorities and further reading
- WADA: Athlete Biological Passport — how the passport works and its guidelines
- WADA: International Standard for Laboratories — the analytical standards samples are judged against
- Court of Arbitration for Sport: Code of Sports-related Arbitration — procedure, including expert evidence and panel-appointed experts
- CAS: recent decisions — the published awards cited on this page
FAQ
Common questions
What does an athlete biological passport (abp) expert witness do?
They give independent, objective opinion to a court or tribunal on athlete biological passport (abp) 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 an athlete biological passport (abp) 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 athlete biological passport (abp) 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.
Can an athlete be banned without a positive test?
Yes. Under the World Anti-Doping Code, the use of a prohibited substance or method can be proved by a biological passport profile and expert opinion, without an adverse analytical finding. That is why the expert evidence decides most passport cases.
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