Swimmer Lia Thomas, who became the first transgender to win the highest US national college title in 2022, has lodged a case with the Court of Arbitration for Sport (CAS) in a bid to again compete in elite female races.
In June 2022 World Aquatics voted to ban transgender women who had gone through male puberty from competing in women's races.
Before then transgender women could compete as long as they lowered their testosterone levels.
However, a scientific panel found that even after reducing their testosterone levels through medication, transgender women still had a significant advantage.
The 25-year-old American has lodged a case with CAS to overturn the ban.
"Ms Thomas accepts that fair competition is a legitimate sporting objective and that some regulation of transgender women in swimming is appropriate," CAS said in a statement.
"However, Ms Thomas submits that the challenged provisions are invalid and unlawful as they discriminate against her."
CAS said arbitration started in September and "was subject to strict confidentiality rules" but the parties had "now agreed that general information concerning the procedure itself be communicated".
CAS added that a hearing date had yet to be set.
The governing bodies in sports such as cycling and athletics have also banned transgender athletes from elite female competition over the past two years.
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