The WADA World Anti-doping Code (WADC) is very strict in terms of an inadvertent violation of anti-doping rules by athletes. According to the strict liability in case of presence of prohibited substance in an athlete’s sample it is presumed that the athlete was in fault, unless contrary is proven. Who is the real cheating wrongdoer and who simply was not careful enough to stay clean and departed from the strict standards of WADC? What is possible justification for athletes not to be punished at all or to obtain reduced sanction? The article explores extent and limits of the principle of strict liability, including review in the light of competition law and human rights. It also evaluates the legitimacy of enforcement of this system.