The final appeals court for global sports further blurred the line separating male and female athletes on Monday, ruling that a common factor in distinguishing the sexes — the level of natural testosterone in an athlete’s body — is insufficient to bar some women from competing against females.

The Court of Arbitration for Sport, based in Switzerland, questioned the athletic advantage of naturally high levels of testosterone in women and therefore immediately suspended the practice of “hyperandrogenism regulation” by track and field’s governing body, the International Association of Athletics Federations.