Double Olympic champion runner Caster Semenya won an appeal against track and field’s testosterone rules Tuesday when the European Court of Human Rights ruled she was discriminated against and there were “serious questions” about the rules’ validity.

World Athletics, which enforces the regulations, said in reaction to the decision that its rules would remain in place, meaning there would not be an immediate return to top-level competition for the South African runner.

Semenya’s case at the rights court was against the government of Switzerland, and not World Athletics itself, although the decision was still a major moment in throwing doubt on the future of the rules.

Semenya was legally identified as female at birth and has identified as female her entire life, but regulations introduced by track and field’s governing body in 2019 forced her to artificially suppress her natural testosterone to be allowed to compete in women’s competitions.

World Athletics says she has one of a number of conditions known as differences in sex development, which results in a natural testosterone level in the typical male range and which gives her an unfair advantage in women’s competitions.

Semenya has been challenging the testosterone rules in the courts for years, but had previously lost an appeal at sport’s highest court in 2019 and a second challenge against the rules at Switzerland’s supreme court in 2020. That second rejection of her appeal was the reason why the Swiss government was the respondent in the European Court of Human Rights case.

The Strasbourg-based rights court ruled in Semenya’s favor by a 4-3 majority of judges on the complaint of discrimination and noted she was denied an “effective remedy” against that discrimination through the two previous cases she lost at the Court of Arbitration for Sport and the Swiss supreme court.

Tuesday’s ruling was in many ways a criticism of the 2019 decision by CAS. The sports court kept in place the rules that require Semenya and others with so-called differences in sex development conditions, or DSDs, to take birth control pills, or have hormone-blocking injections, or undergo surgery to be allowed to run at top competitions such as the Olympics and world championships.

The rules were initially enforced in certain events but were expanded and made stricter by World Athletics this year. Athletes such as Semenya were forced to lower their testosterone further if they wanted to run in any race.

The decision by the Switzerland-based CAS that rejected Semenya’s first appeal had not properly considered important factors such as the side effects of the hormone treatment, the difficulties for athletes to remain in compliance of the rules, and the lack of evidence that their high natural testosterone actually gave them an advantage, the European rights court said.

An unfair advantage is the core reason why World Athletics introduced the rules in the first place.

The European rights court also found Semenya’s second legal appeal against the rules at the Swiss supreme court should have led to “a thorough institutional and procedural review” of the rules, but that did not happen when that court also ruled against Semenya.

The government of Switzerland was ordered to pay Semenya 60,000 euros ($66,000) in respect of costs and expenses by the European rights court.

Ultimately, the rules have sidelined Semenya since 2019 as she has refused to artificially suppress her natural hormone levels in order to run, and the European rights court noted the “high personal stakes” for Semenya in how the regulations interrupted her career and affected her “profession.”

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.”

The 32-year-old Semenya is aiming to run at next year’s Olympics in Paris. She was the 2012 and 2016 Olympic champion in the 800 meters but did not defend her title at the Tokyo Olympics because of the regulations.