The governing body of world athletics has hailed the Swiss court decision that ruled Caster Semenya out of its world championships as a victory for "parity and clarity."
Olympic 800 metres champion Semenya is fighting an International Association of Athletics Federations (IAAF) regulation that middle distance female runners with a high natural level of testosterone must take medication to reduce it.
On Tuesday, the Swiss Federal Tribunal (SFT) reversed a ruling that temporarily lifted the IAAF's testosterone regulations imposed on her, effectively ruling her out of the world championships to be staged Sept. 28 to Oct. 6 in Doha, Qatar.
"This decision creates much needed parity and clarity for all athletes as they prepare for the world championships in Doha this September," the IAAF said in a statement.
The Court of Arbitration for Sport (CAS) ruled the IAAF's regulations were necessary for athletes with differences in sexual development (DSDs) to ensure fair competition.
CAS is based in Lausanne and comes under the jurisdiction of Switzerland's highest court.
Semenya, who is appealing the CAS ruling at the SFT, has said she does not wish to take medication to change who she is and how she was born, and she wants to compete naturally.
The IAAF said during the remainder of the SFT hearing it would "maintain its position that there are some contexts, sport being one of them, where biology has to trump gender identity."
"The IAAF believes ... that the DSD Regulations are a necessary, reasonable and proportionate means of protecting fair and meaningful competition in elite female athletics."
Semenya ran the quickest ever 800 metres on United States soil at the Prefontaine Classic Diamond League meeting on June 30 in a time of 1:55.70.