The Grand Chamber of the European Court of Human Rights will hear the case involving middle-distance runner Caster Semenya on Wednesday before a final ruling.
Semenya, 32, was born with differences of sexual development (DSD) and cannot compete in female track events without taking testosterone-reducing drugs.
The South African believes World Athletics is showing discrimination against athletes with her condition.
Last July, the ECHR ruled in favour of Semenya in a case related to testosterone levels in female athletes.
The case at the ECHR was not against sporting bodies or DSD rules – but specifically against the government of Switzerland for not protecting Semenya’s rights and dates back to a Swiss Supreme Court ruling three years ago.
The Swiss government requested the matter be referred to the court’s Grand Chamber.
The ECHR Grand Chamber, external is convened in exceptional cases and comprises 17 judges with its verdicts not open to appeal.
As the case concerns the Swiss government and not athletics’ governing body, it is unlikely the decision will immediately affect the current restrictions on DSD athletes.
World Athletics rules restrict testosterone levels in female runners competing in track events from 400m up to the mile.
Semenya, and other athletes with DSD who have testosterone levels above the approved level, cannot compete in female track events without taking testosterone-reducing medication.
Semenya said in October last year she was turning her attention to “winning battles against the authorities” rather than collecting medals.
She appealed against World Athletics’ rules at the Switzerland-based Court of Arbitration for Sport (Cas), but eventually lost in what amounted to a landmark case in 2019.
Switzerland’s top court rejected another appeal by Semenya in September 2020, after her team again sought to challenge the Cas ruling.
It was this last act by the Swiss court that formed the basis of a 2021 application lodged by Semenya at the ECHR.
World Athletics has said its DSD regulations “are a necessary, reasonable and proportionate means of protecting fair competition in the female category”.