Thomas made history in 2022, becoming the first transgender woman to win an NCAA  swimming championship.

 Lia Thomas. Rich von Biberstein / Icon Sportswire via Getty Images file

Transgender swimmer Lia Thomas lost a legal battle Wednesday challenging an effective ban on trans women competing in the highest levels of women’s swimming, dashing her hopes of making the Summer Olympics in Paris next month.

Three judges on the  Court of Arbitration for Sport dismissed Thomas’ request for arbitration with the World Aquatics governing body.

“The panel concludes that she lacks standing to challenge the policy and the operational requirements in the framework of the present proceeding,” the court said Wednesday in its ruling.

Thomas, who seldom gives media interviews, told ABC News’ “Good Morning America” in 2022 that one of her lifelong goals was to compete in the Olympics.

With Wednesday’s ruling in place, she will be unable to participate in this month’s qualifying trials to compete in the Olympics.

Under rules established in 2022, World Aquatics banned transgender women who have been through male puberty from competing in women’s races. It also created an “open” category for which transgender athletes would be eligible.

Thomas had asked the sports court in Switzerland to overturn the rules last year, arguing they were invalid, unlawful and discriminatory. The rules were established several months after Thomas, then a student at the University of Pennsylvania, became the first trans woman to win an NCAA swimming championship in 2022.

“The CAS decision is deeply disappointing,” Thomas said in a statement through her attorney. “Blanket bans preventing trans women from competing are discriminatory and deprive us of valuable athletic opportunities that are central to our identities.”

“The CAS decision should be seen as a call to action to all trans women athletes to continue to fight for our dignity and human rights,” Thomas added.

The CAS did not immediately return a request for comment.

World Aquatics said it welcomed the CAS decision in a case “we believe is a major step forward in our efforts to protect women’s sport.”

Thomas’ NCAA win drew international media attention, putting her at the center of an ongoing global debate over whether trans women should be allowed to compete in women’s sports. Her success also made her a frequent target of right-wing media.

Former University of Kentucky swimmer Riley Gaines, who in recent years has become vocal critic of Thomas in conservative media, celebrated Thomas’ legal defeat on X.

“This is a victory for women and girls everywhere,” Gaines, who is also suing the NCAA for allowing Thomas to compete in the 2022 championships, wrote while also misgendering Thomas.

Athlete Ally, a nonprofit that advocates for the inclusion of LGBTQ in sports, condemned the ruling.

“By dismissing Lia Thomas’ legal challenge against World Aquatics, the CAS has denied her fundamental right to access an effective remedy for acts that violate her human rights,” Hudson Taylor, the founder and executive director of Athlete Ally, said in a statement. “This is a sad day for sports and for anyone who believes that trans athletes should have the opportunity for their experiences of discrimination to be heard and adjudicated like everyone else.”