Caster Semenya v. International Association of Athletics Federations

In 2018, the International Association of Athletics Federations (IAAF) (defendant) enacted Eligibility Regulations for the Female Classification – Athletes with Differences of Sex Development (the DSD Regulations). The DSD Regulations governed female athletes’ participation in eight events in international athletics competitions, including the 400-meter, 800-meter, and 1500-meter races. The DSD Regulations applied to female athletes with a genetic condition called 46 XY DSD, who had a natural testosterone level exceeding 5 nmol/L and who experienced a “material androgenizing effect” from the elevated testosterone as determined in a medical examination. Affected athletes had to reduce their testosterone levels below 5 nmol/L (e.g., by taking oral contraceptives) and continuously maintain the reduced levels for at least six months before competing in the specified events. Caster Semenya (plaintiff) was an elite female South African runner who specialized in middle-distance events including the 800-meter race. Semenya and Athletics South Africa (ASA) (plaintiff) brought an action against the IAAF in the Court of Arbitration for Sport to prevent enforcement of the DSD Regulations, asserting that the regulations unfairly discriminated against athletes on the basis of sex or gender. The IAAF submitted evidence that the adult male testosterone level was the main factor that gave male athletes a competitive advantage over female athletes in sports performance. The IAAF also submitted evidence regarding actual performance by and statistical overrepresentation of female athletes with 46 XY DSD in the specified racing events. The IAAF argued that the DSD Regulations were necessary to safeguard fair competition for female athletes who lacked the testosterone-derived advantage.