Athlete Caster Semenya will not have to take hormone suppressants to compete while her appeal against an IAAF ruling is pending.
The Federal Supreme Court of Switzerland has instructed the IAAF to suspend the implementation of the eligibility regulations against Semenya.
The South African track star lost her appeal on May 1 against International Association of Athletics Federations' (IAAF) rules designed to decrease naturally high testosterone levels in female runners.
Ruling on her appeal to the Court of Arbitration for Sport, the panel said the regulations are discriminatory but concluded such discrimination is a "necessary, reasonable and proportionate means" of preserving the integrity of female athletics.
But the Federal Supreme Court of Switzerland has now told the IAAF to suspend eligibility regulations against Semenya while the 28-year-old’s fresh appeal is judged.
This means the double 800m Olympic champion is now free to compete.
"I am thankful to the Swiss judges for this decision. I hope that following my appeal I will once again be able to run free," she said.
Swiss lawyer Dorothee Schramm said the decision was a “welcome temporary protection”.
She added: “This is an important case that will have fundamental implications for the human rights of female athletes.”
Why was Semenya banned from competing without medication?
Matthieu Reeb, Secretary General of Court of Arbitration for Sport, told reporters last month the panel found regulations are discriminatory but "necessary".
He said: "The panel found that the DSD (differences in sexual development) regulations are discriminatory, but the majority of the panel found that on the basis of the evidence submitted by the parties in the procedure, such discrimination is a necessary, reasonable and proportionate means of achieving the IAAF's objective of preserving the integrity of female athletics in some track events of international competitions, that is from 400 metres to one mile."
How does Semenya's different hormone level affect the sport?
Semenya has a condition called hyperandrogenism which means her testosterone levels are naturally elevated.
Testosterone is a hormone that strengthens muscle tone and bone mass. Because of that, it is against the rules for athletes to inject or swallow testosterone supplements.
The average testosterone levels for women are between 0.52 and 2.43 nmol/L (nanomoles per litre of blood), while for men it is between 10.41 to 34.70.
After winning the 800m at the World Championships in 2009 at the age of 18, Semenya was forced to spend 11 months on the sidelines while she underwent sex verification testing.
The results of the tests were never made public, but the 28-year-old was cleared to compete again in women's events in 2010.
Unconfirmed reports suggest that Semenya may have up to three times the testosterone levels of the average woman.
Now, the International Association of Athletics Federation (IAAF) plans to reduce the testosterone limit level from 10 nanomoles per litre to five for female athletes.
The International Olympic Committee is planning to do the same.