Switzerland's supreme court has dismissed the appeal of Olympic champion, Caster Semenya, against a Court of Arbitration for Sport (CAS) ruling last year. The CAS had ruled that Semenya would have to take testosterone-reducing drugs in order to compete professionally.

"The CAS had the right to uphold the conditions of participation issued for female athletes with the genetic variant '46 XY DSD' in order to guarantee fair competition for certain running disciplines in female athletics," the Swiss court said.

According to the CAS, regulations of the sport's governing body World Athletics are necessary for athletes with differences in sexual development (DSDs) in races ranging from 400 meters to a mile to ensure fair competition. World Athletics has banned Semenya and other DSD athletes from races unless they take testosterone-reducing drugs.

World Athletics (until recently known as the IAAF) wants to introduce a testosterone limit of five nanomoles per liter for athletes competing in international events between 400 meters and a mile.

Women who have higher values would be required to lower their levels them by taking hormonal-suppressing medication — such as birth-control pills — over a minimum period of six months prior to competition.

Read more:  Opinion: The Caster Semenya verdict is 'wrong and demeaning'

Biological differences give unfair advantage?

Semenya is born with the "46 XY" chromosome rather than the XX chromosome of most females. She is classified as a woman, was raised as a woman and races as a woman, but World Athletics and some of her opponents argue that her unusual biology gives her a competitive advantage. Testosterone levels can increase athletes' muscle mass, strength and oxygen-carrying hemoglobin levels in the blood, which can improve stamina.

World Athletics argues that it is seeking to "to ensure fair competition for all women" by restricting the participation of women with certain "masculine attributes" attributable to DSD. 

Following the dismissal from the Swiss supreme court, Semenya vowed to continue her "fight for human rights" by seeking to appeal again in European and South African courts.

"I am very disappointed by this ruling, but refuse to let World Athletics drug me or stop me from being who I am," said Semenya said in a statement.

Following her first major international title in 2009 as a teenager, the IAAF (as it was known then) ordered a test to check whether Semenya really was a woman. She was barred from competition initially but was then allowed to return in mid-2010. 

In South Africa she's seen as a hero and her country's government has repeatedly complained that Semenya is being subjected to international discrimination.

am/msh (AFP, AP, Reuters)