Lia Thomas

The international swimming federation said transgender women who had experienced male puberty could not compete in women's events.

“At the international level, there is some logic to do this,” she said of the restrictions. Harper, who supports sport-specific restrictions on testosterone levels for transgender women at the international level, said she was concerned that even local organizations would feel justified in barring transgender athletes. She said the regulations would “not be enforceable without seriously violating the privacy and human rights of any athlete looking to compete in the women’s category.” In 2019, the court upheld the world track and field federation’s regulations on athletes born with both male and female genitalia that had prohibited them from competing unless they took medication to suppress their testosterone levels. Thomas, who competed for the University of Pennsylvania, was lauded by supporters as a brave and courageous athlete this year, but her performance also sparked a backlash. But it also said that “until evidence determines otherwise, athletes should not be deemed to have an unfair or disproportionate competitive advantage due to their sex variations, physical appearance and/or transgender status.” Tim Hinchey III, the chief executive of U.S.A. Swimming, did not respond to a message on Sunday. During Thomas’s championship season, U.S.A. Swimming, the sport’s national governing body, passed new rules that allowed transgender women to compete if they had taken medication that had sufficiently suppressed their testosterone levels continuously for 36 months. I’m a woman, so I belong on the women’s team.” She has also said that she hopes to try to qualify for the U.S. Olympic team in 2024. More than 70 percent of FINA’s member federations voted to adopt the policy, which was devised by a working group set up in November that included athletes, scientists and medical and legal experts. The move, however, came just three months after Lia Thomas became the first transgender woman to win an N.C.A.A. Division I swimming championship — she won the 500-yard women’s freestyle — putting a spotlight on the issue. The vote by FINA, which administers international competitions in water sports, prohibits transgender women from competing unless they began medical treatments to suppress production of testosterone before going through one of the early stages of puberty, or by age 12, whichever occurred later.