Controversial transgender swimmer Lia Thomas is taking secret legal action in a bid to overturn a ban on biological males competing alongside women – and hopes to take part in the Paris Olympic trials, according to a report.

Thomas, 24, has hired the Canadian law firm Tyr to ask the Court of Arbitration for Sport in Switzerland to overturn the rules imposed by World Aquatics after she became the first openly trans person to win an NCAA Division I title, the Telegraph reported.

She has not competed since 2022, when World Aquatics introduced rules that prohibit anyone who has undergone “any part of male puberty” from the female category.

Prior to that, trans women were allowed to compete if they lowered their testosterone levels.

Tyr describes its staff as “fearless advocates” who have been involved in “high-stakes and precedent-setting cases” – but those brought before the CAS are controversially heard behind closed doors unless those involved agree to publicize them, according to the outlet.