University of Pennsylvania swimmer Lia Thomas on the starting blocks during the 500 Freestyle finals during the NCAA Swimming and Diving Championships on March 17th, 2022 at the McAuley Aquatic Center in Atlanta Georgia. (Photo by Rich von Biberstein/Icon Sportswire via Getty Images)

FINA, swimming’s world governing body, has voted to enact a new policy restricting transgender participation in elite competitions.

The move, announced Sunday, requires transgender athletes to have completed their transition by age 12 in order to compete in women’s competitions.

Taking effect Monday, the new policy also includes the establishment of a working group to create a new “open” category for swimmers that don’t meet the criteria for men’s or women’s categories.

“This is not saying that people are encouraged to transition by the age of 12. It’s what the scientists are saying, that if you transition after the start of puberty, you have an advantage, which is unfair,” James Pearce, the spokesperson for FINA president Husain Al-Musallam, told The Associated Press. “They’re not saying everyone should transition by age 11; that’s ridiculous. You can’t transition by that age in most countries, and hopefully you wouldn’t be encouraged to. Basically, what they’re saying is that it is not feasible for people who have transitioned to compete without having an advantage.”

The ruling comes after Lia Thomas became the first openly transgender woman to win an NCAA Division I women’s swimming title in March. Sunday’s announcement will have critical implications for Thomas’ future in the sport.

“The new FINA release is deeply upsetting. It is discriminatory and will only serve to harm all women,” said Thomas, Per ESPN.

Thomas has expressed a goal of swimming on the 2024 U.S. Olympic team, but her Olympic dreams would be dashed under the new FINA mandate.

USA Swimming responded to the news Monday, saying the federation would examine its policy.

“USA Swimming continues to promote inclusivity in our sport while also ensuring competitive equity,” the federation said in a statement. “We understand the enormous effort undertaken by FINA to build their gender inclusion and equity policy; USA Swimming will now take our time to understand the impact of this international standard on our existing policy.”

The announcement has ignited a passionate response from actors on both sides of the discussion regarding transgender participation in sport. Anne Lieberman of Athlete Ally, a nonprofit advocating for LGBTQ+ athletes, calls the policy “deeply discriminatory, harmful and unscientific.”

“The eligibility criteria for the women’s category as it is laid out in the policy [will] police the bodies of all women, and will not be enforceable without seriously violating the privacy and human rights of any athlete looking to compete in the women’s category,” Lieberman said.