Transgender swimmer Lia Thomas is asking the Court of Arbitration for Sport (CAS) to overturn a policy that would otherwise prevent her from competing in women's races at elite competitions, the Swiss-based court announced Friday.

Thomas, the first openly transgender athlete to win an NCAA championship at the Division I level, has argued that the gender inclusion policy created by swimming's international federation, World Aquatics, is discriminatory.

In 2022, the federation's policy effectively banned transgender competitors from competing in men's or women's races at elite competitions, such as the Olympic Games or world championships, while proposing the creation of “open category” races for transgender competitors.

"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 news release. "However, Ms. Thomas submits that the Challenged Provisions are invalid and unlawful as they discriminate against her contrary to the Olympic Charter, the World Aquatics Constitution, and Swiss law including the European Convention on Human Rights and the Convention on the Elimination of All Forms of Discrimination against Women."

A lawyer identified in media reports as representing Thomas did not immediately reply to a message from USA TODAY Sports seeking comment.

World Aquatics said in a statement provided to USA TODAY Sports that its policy, which was adopted in June 2022, was "rigorously developed on the basis of advice from leading medical and legal experts, and in careful consultation with athletes."

"World Aquatics remains confident that its gender inclusion policy represents a fair approach, and remains absolutely determined to protect women's sport," the international federation said.

CAS said Thomas' case has been ongoing since September. It had remained confidential until Friday, when British media outlets first reported on the case, prompting the parties to authorize CAS to disclose it.

No hearing date has been set, which makes it unlikely that CAS will rule on the matter before the U.S. Olympic trials in June and the 2024 Paris Olympics, which start in late July.

Thomas, 25, won the 500-yard freestyle at the 2022 NCAA women’s swimming and diving championships, when she was a student at the University of Pennsylvania. She told ESPN and ABC News a few months later that she transitioned to be happy, not to win a race in the pool.

"Trans women competing in women's sports does not threaten women's sports as a whole," Thomas told the outlets in a televised interview. "Trans women are a very small minority of all athletes. The NCAA rules regarding trans women competing in women's sports have been around for 10- plus years. And we haven't seen any massive wave of trans women dominating."

CAS' decision on Thomas' case could have ripple effects in other sports that have implemented restrictions on transgender competitions, including track and field and cycling.

Contributing: The Associated Press

Contact Tom Schad at [email protected] or on social media @Tom_Schad.