The Court of Arbitration for Sports rejected transgender swimmer Lia Thomas's challenge against the World Aquatics governing body on Wednesday over its rule that prohibits biological men from competing in women's competitions, per the Associated Press.

The three-judge panel ruled that Thomas's request lacked standing and dismissed the case. World Aquatics welcomed the decision and said it's another step forward "in our efforts to protect women's sports."

In 2022, World Aquatics banned male-identified trans swimmers who have gone through male puberty from competing in women's categories. The swimming governing body created a separate "open" category for transgender athletes to compete in.

Thomas petitioned the Switzerland sports court to overturn the rules, claiming that the policy was discriminatory, invalid, and unlawful. The rules bar Thomas from competing in the Olympics.

The transgender swimmer, a biological male, swam for the University of Pennsylvania and won an NCAA title in women's competitions. Thomas dominated female competitors, breaking records along the way. Thomas did not compete in the World Aquatics competitive system but filed the case to be able to compete at the highest level. 

The judges argued in the court filing that USA Swimming had no authority "to modify such scope of application" of the world governing body rules, and ruled that Thomas "lacks standing to challenge the policy and the operational requirements in the framework of the present proceeding."

Riley Gaines, a former collegiate swimmer who was forced to compete against Thomas, applauded the ruling on X and said: "Now the NCAA needs to strip him of every award, title, and record he stole from a deserving female athlete."