Caster Semenya

South Africa's Semenya approached the tribunal in May last year, after CAS - sport's highest court - ruled that World Athletics regulations were necessary for athletes with differences in sexual development (DSDs) to ensure fair competition in races ranging from 400m to a mile. 

The tribunal found the requirement of subjecting certain female athletes to drug or surgical interventions as a precondition to compete does not amount to a violation of Swiss public policy, Semenya's lawyer says. 

The two-time Olympic 800 metres champion challenged a new IAAF ruling that will require her to take medication to lower her testosterone levels in order to compete against women in track events ranging from 400m to a mile.

Semenya ruled out retiring after winning the 800m at the Diamond League event in Doha, just two days after the CAS ruling was announced at the start of this month.

The new regulation has since been implemented and Semenya has now launched a fresh appeal amid uncertainty over her future in the sport.

South African Semenya, the double defending Olympic champion over 800 metres, and Athletics South Africa had challenged the IAAF's new regulations concerning athletes with differences of sex development (DSD).

The rules in question require athletes with naturally-occurring high levels of testosterone to take medication to reduce those levels, in order to compete in women's track events ranging from 400m to a mile.

In April, Athletics' governing body announced new regulations affecting women with higher than normal levels of testosterone who compete in track events ranging from the 400 metres up to a mile.

Two-time Olympic gold medallist Semenya is among the athletes who will still be eligible to compete, but only provided testosterone levels are within set limits for a continuous period of at least six months.

A commanding win in the women's 800-metre final saw the South African double up on her earlier 1,500m victory to clinch the 800-1500 double she just missed out on at last year's world championships.

Both golds in Carrara came in Commonwealth Games record time.

But where the 1,500m win came amid talk of indifference from other athletes which has long surrounded her due to her hyperandrogenism (meaning she has an excess of male sex hormones in her body, including testosterone) the 800m victory came in seemingly friendlier conditions.