The International Olympic Committee announced Thursday that it will restrict participation in all female Olympic events to biological females, implementing a new eligibility policy that will take effect ahead of the 2028 Summer Games in Los Angeles.

Under the policy, eligibility for women’s categories at IOC-sanctioned events will be determined through a one-time screening for the SRY gene, which is associated with male biological development. The organization said the measure is intended to ensure fairness, safety, and integrity in female competition across both individual and team sports.

The decision follows ongoing international debate over the inclusion of transgender-identifying male athletes in women’s sports. It aligns with broader policy shifts in several countries, including recent executive action in the United States addressing the issue.

IOC officials indicated the rule is not retroactive and will not affect grassroots or recreational athletics. The policy is designed specifically for elite international competition and reflects a growing effort to standardize eligibility requirements across sports.

Questions remain about how many transgender-identifying male athletes are currently competing at the Olympic level. However, high-profile cases have drawn attention to the issue in recent years. Algerian boxer Imane Khelif, who won gold in women’s boxing at the 2024 Paris Olympics, has faced scrutiny over eligibility standards. Khelif previously acknowledged undergoing hormone treatments to reduce testosterone levels to compete.

The newly released IOC policy also addresses athletes with differences in sex development (DSD), including competitors such as two-time Olympic champion Caster Semenya. These conditions, which can involve atypical chromosomal or hormonal traits, have been the subject of regulatory disputes in track and field and other sports.

IOC President Kirsty Coventry initiated a comprehensive review of female category eligibility shortly after assuming leadership, aiming to establish a unified standard rather than relying on individual sports federations to set their own rules. Before the Paris Olympics, organizations governing track and field, swimming, and cycling had already enacted policies restricting participation by transgender women who had undergone male puberty.

According to the IOC’s findings, biological males experience multiple stages of testosterone exposure, from prenatal development through puberty and adulthood, that contribute to lasting physical advantages in strength, endurance, and power. The committee cited this research as a central factor in shaping the updated policy.

The 10-page framework represents one of the most significant changes to Olympic eligibility rules in recent years and comes as international sports organizations face increasing pressure to clarify standards governing female competition.