Tony Hansen, an equestrian athlete, appealed against a decision by the Fédération Equestre Internationale (FEI) regarding a doping violation involving his horse, Camiro, during the 2008 Beijing Olympics. The horse tested positive for capsaicin, a prohibited substance, leading to the disqualification of Hansen and the Norwegian team, forfeiture of medals and prize money, and additional sanctions including a suspension and fines. Hansen argued that the substance might have contaminated the urine sample during or after collection rather than being present in the horse’s body. The Court of Arbitration for Sport (CAS) panel upheld the FEI’s decision, emphasizing that capsaicin, though not explicitly listed as prohibited, falls under the definition of a banned pain-relieving substance under FEI rules. The panel affirmed the strict liability rule, meaning the presence of a prohibited substance in a sample is sufficient to establish an offense unless proven otherwise, with the burden of proof lying on the accused. Hansen failed to provide conclusive evidence of contamination or other mitigating factors. The panel dismissed arguments questioning the validity of the testing process, stating there was no evidence of irregularities in sample collection or analysis. While Hansen suggested a conjugation test could determine whether capsaicin entered the urine externally, the panel ruled such a test was not mandatory under FEI rules. The CAS clarified its role as an adjudicative body, not a legislative one, and found no conflict with fundamental legal principles. Regarding sanctions, the panel upheld the FEI’s decision, noting Hansen did not provide sufficient evidence to reduce the penalty. The absence of a clear explanation for the presence of capsaicin meant there was no basis for leniency. The CAS concluded that the disqualification and sanctions were justified, reinforcing the strict liability principle in anti-doping regulations and the necessity for athletes to ensure their horses are free of prohibited substances. The case underscores the importance of maintaining clean sport and the integrity of competition, with the ruling emphasizing rigorous testing protocols and the need for conclusive evidence in doping cases. The Court of Arbitration for Sport ultimately dismissed Hansen’s appeal, upholding the FEI Tribunal’s decision in its entirety.