Caster Semenya has won her appeal at the European Court of Human Rights (ECHR) to challenge whether her rights had been infringed by rules requiring women athletes with natural high testosterone to reduce those levels through medication.
The ECHR ruled the South African 32-year-old was discriminated against by the Swiss state and there were "serious questions" about the rules' validity.
Earlier legal challenges at the Court of Arbitration for Sport (CAS) and the Swiss Federal Court had been rejected, but the ECHR found Switzerland had not afforded Semenya "sufficient institutional and procedural safeguards" to allow her to have her complaints examined effectively.
The seven ECHR judges found by a majority of four to three that Semenya's rights under Article 14 of the European Convention on Human Rights, which concerns discrimination, had been violated by Switzerland. The Swiss state was
also found to have violated Article 13 in not providing Semenya effective remedy against discrimination.
- Zharnel Hughes breaks Linford Christie's 30-year British 100m record
- Police raid headquarters of Paris Olympics in suspected corruption probe
- Dina Asher-Smith to race in London Diamond League
Separately, World Athletics, which enforces the regulations, said in reaction to the decision that its rules would remain in place.
Tuesday's decision could force CAS and ultimately World Athletics to re-examine the regulations, although the path and timeline to a possible rollback of the rules is unclear.
In a statement, World Athletics said: "We remain of the view that the DSD regulations are a necessary, reasonable and proportionate means of protecting fair competition in the female category as the Court of Arbitration for Sport and Swiss Federal Tribunal both found, after a detailed and expert assessment of the evidence."
Semenya approached the France-based court in February, 2021 after losing appeals to CAS, sport's highest court, and another plea to the Swiss Federal Tribunal (SFT) in a long-running legal battle against the regulations.
The double Olympic champion, who won the women's 800m titles in 2012 and 2016, has been banned from running in races from 400m to one mile since 2019 due to her intersex condition 46, XY difference in sex development.
Regulations demand that women undergo medical intervention to lower their natural hormone levels to below a certain threshold if they want to run in those races.
Semenya and other runners who fall under the DSD (differences in sex development) rules have declined to do so and have been forced to compete in other unregulated events for the last three years.
Earlier this year, World Athletics confirmed it will exclude male-to-female transgender athletes who have gone through male puberty from female competition.
Semenya is not transgender. She was assigned female at birth, raised as a girl, identifies as a woman and has never publicly identified herself as intersex.
However, she essentially acknowledged having the condition by appealing the DSD rules at the Court of Arbitration for Sport in 2018, which she lost.
The transgender and DSD issues are different but often have crossover because they both deal with the question of whether women with high natural testosterone higher than the typical female range should be allowed to compete in female sport.
On World Athletics' decision to exclude male-to-female transgender from competing in female competition, president Lord Coe said: "We have also taken decisive action to protect the female category in our sport, and to do so by restricting the participation of transgender and DSD athletes.
"The decision has been taken in consultation with a number of stakeholders including 40 member federations, our athletes, our coaches and through the athletes commission, as well as a range of other community groups, including trans groups, UN experts, the IOC and Para-athletics.
"The majority of those consulted stated that transgender athletes should not be competing in the female category.
"Many believe there is insufficient evidence that trans-women do not retain advantage over biological women, and want more evidence that any physical advantages have been ameliorated before they are willing to consider an option for inclusion into the female category."