Sidley Austin is acting for Olympic gold medallist Caster Semenya as she appeals a decision to require her to limit her testosterone levels.

The South African middle-distance runner has appealed to the Federal Supreme Court of Switzerland, challenging the recent ruling against her by the Court of Arbitration for Sport (CAS).

On May 1, CAS ruled in favour of world athletics governing body the International Association of Athletics Federations (IAAF), which had enforced a testosterone limit for individuals with disorders of sex development (DSD).