Caster Semenya is temporarily free to compete in her preferred 800m event without taking medication to lower her testosterone levels as she awaits the result of an appeal against an IAAF ruling.
The Federal Supreme Court of Switzerland has instructed the IAAF to suspend the implementation of the eligibility regulations against Semenya.
The 28-year-old has appealed against the introduction of a testosterone limit for women with naturally-occurring high levels of testosterone.
The IAAF's rule change was last month supported by the Court of Arbitration for Sport, resulting in Semenya's appeal to the Swiss court.
"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," Semenya said.
The IAAF's controversial ruling means Semenya, and other athletes with similar genetic conditions, would have to take testosterone-reducing medication to bring their testosterone down to a level closer to the typical female range.
The double 800m Olympic champion can run in events from 400m to the mile by taking medication, a course of action she declared she would not take.
"The Swiss Supreme Court has granted welcome temporary protection to Caster Semenya," Semenya's Swiss lawyer Dorothee Schramm said.
"This is an important case that will have fundamental implications for the human rights of female athletes."
Additional reporting by the Press Association.
