“Future Olympians are counting on the IOC to protect the opportunities of women and girls to contribute to this proud tradition,” the lawmakers wrote.“To do so, the IOC must base eligibility for women’s athletic competitions on biological sex. Allowing biological males to compete in women’s categories undermines competitive opportunities, safety, and respect for female athletes.” 

The Olympics have allowed transgender athletes to compete since 2004, though the first year a transgender athlete competed was 2021. Under the 2004 consensus, individuals who have undergone sex reassignment surgery are allowed to compete among the gender they’ve transitioned to.

The letter comes ahead of the IOC’s March 17 meeting, the agenda of which includes electing its next president and preparing for the 2028 Summer Olympics in Los Angeles. 

The lawmakers referenced in the letter President Donald Trump’s Feb. 5 executive order, which prohibited biological men from competing in women’s sports.

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Controversy arose during the 2024 Paris Olympics over the gender of Algerian boxer Imane Khelif, who won gold in women’s boxing.

Khelif was diagnosed with differences in sexual development. This is a diagnosis in which a person can have either XY or XX chromosomes but not the corresponding physical sex characteristics. She was disqualified from the female International Boxing Association championship in 2023 after genetic testing revealed she had XY chromosomes. However, she was able to compete in the women’s category under the International Olympic Committee’s guidelines for testing testosterone levels.