Lia Thomas, the swimmer, lost her appeal against the swimming governing body regarding transgender people.
The American became the first transgender woman to become a college champion in the USA in 2022, but is not allowed to compete internationally.
According to the International Swimming Federation's transgender rules, which were introduced in 2022, a person born as a man must have undergone gender correction before the age of 12 to be allowed to compete with women.
Lia Thomas began her gender correction at the age of 20 in 2019.
Thomas appealed against the swimming rules to the Court of Arbitration for Sport (CAS).
The court writes in its decision that Thomas does not have the authority to appeal the case since she does not belong to international swimming. College teams do not belong to the International Swimming Federation.
The International Swimming Federation writes in a comment that they welcome the decision "which we perceive as a major step forward in our attempt to protect women's sports".
