The United States Supreme Court on Tuesday upheld state laws in Idaho and West Virginia that bar transgender women and girls from participating in female school and college sports. The justices ruled unanimously that such bans do not violate Title IX, the 1972 federal law prohibiting sex discrimination in education, and by a 6-3 conservative majority that they do not contravene the 14th Amendment’s equal protection guarantee. The decision effectively validates similar legislation in at least 25 other states, allowing them to require that athletes compete on teams matching their biological sex at birth.

According to the court’s majority opinion, authored by Justice Brett Kavanaugh, the term “sex” in Title IX refers to biological sex, and separate teams are justified by inherent physical differences, with states having a substantial interest in safety and competitive fairness. The three liberal justices dissented in part; Justice Sonia Sotomayor argued the ruling “rests on assumptions rather than facts,” while Justice Ketanji Brown Jackson contended that Title IX accommodates gender identity. The Trump administration, which intervened in support of the states, described the outcome as ensuring “women’s sports will only be for women.” President Trump, who had signed an executive order to withhold federal funds from schools permitting transgender athletes on girls’ teams, called it a “big win” that ends a “ridiculous situation.” Civil rights groups, including the American Civil Liberties Union, which represented the student plaintiffs, condemned the decision as discriminatory and a setback for transgender youth.

The ruling does not impose a nationwide ban; it leaves states free to adopt inclusive policies. However, viewed from Washington, it reinforces a broader conservative legal trajectory on transgender rights, following the court’s 2025 decision allowing states to prohibit gender-affirming medical care for minors. The decision also aligns with recent moves by sports governing bodies: the International Olympic Committee announced in March that transgender women would be excluded from women’s Olympic categories, citing a scientific consensus on male performance advantages, and the NCAA had already imposed similar restrictions. In state legislatures, the ruling is expected to embolden further measures, while in states with protective laws, legal challenges may shift to state constitutional grounds.

The cases originated from challenges by Becky Pepper-Jackson, a West Virginia teenager who had been taking puberty blockers and oestrogen, and Lindsay Hecox, a college runner in Idaho. Lower courts had found the bans likely unconstitutional, but the Supreme Court reversed those rulings. The court’s opinion acknowledged the desire of transgender students to compete but described many sports as a “zero-sum game” where inclusion could displace others. The decision leaves unresolved the factual dispute over whether testosterone suppression eliminates competitive advantages, a point the dissent highlighted. The immediate effect is that the Idaho and West Virginia laws, and similar statutes across more than half the country, can now be enforced without federal legal impediment. Future litigation may focus on the application of these laws to individual athletes or on state-level equal protection claims.