The U.S. Supreme Court on Tuesday upheld state laws barring transgender athletes from competing in women’s and girls’ sports, delivering a definitive legal victory to Idaho — the first state to enact such a restriction — and clearing the way for similar laws across the country to remain in force.

The ruling, issued on the final day of the court’s 2025-26 term, resolved a six-year legal challenge to Idaho’s Fairness in Women’s Sports Act, which the legislature passed in 2020. The decision also addressed a separate West Virginia law enacted in 2021.

The Ruling

Justice Brett Kavanaugh authored the majority opinion, joined by Chief Chief Justice John Roberts and Justices Samuel Alito, Amy Coney Barrett, Neil Gorsuch, and Clarence Thomas. The 77-page set of opinions settled two cases simultaneously, one involving Idaho and one involving West Virginia.

“May schools determine eligibility for women’s and girls’ sports based on biological sex?” Kavanaugh wrote. “The answer is yes.”

Justice Sonia Sotomayor authored a partial dissent, which Justices Elena Kagan and Ketanji Brown Jackson joined.

Idaho’s Role as the Pioneer

Idaho broke new legal ground in 2020 when it became the first state to enact a transgender athletics ban at the legislative level. In the years that followed, 26 other states passed comparable laws — many of which faced their own court challenges while Idaho’s case wound through the federal judiciary.

The Idaho law was sponsored by Rep. Barbara Ehardt, a Republican from Idaho Falls and a former collegiate women’s basketball coach. Ehardt framed the legislation from the beginning as a matter of competitive fairness for female athletes.

“Women were told we didn’t matter,” Ehardt said following the ruling. “I said we DO matter. Today, we have finally, definitively won this war for women in sports on all fronts.”

Governor Brad Little, who signed the original legislation and was named as a defendant in the subsequent lawsuit, had defended the law throughout the litigation.

The Legal Battle

The Idaho case centered on Lindsay Hecox, a transgender student athlete who sued the state challenging the law’s constitutionality. The litigation stretched across six years before reaching its conclusion at the nation’s highest court. Hecox moved to drop the case in September, though the Supreme Court proceeded to resolve the broader constitutional questions presented by the combined cases.

The West Virginia case involved transgender athlete B.P.J., who sued that state over its 2021 blanket ban. Both cases raised similar legal questions about whether state legislatures have the authority to set sex-based eligibility rules for athletic competition.

Broader Impact

With the ruling now final, the legal framework governing women’s sports eligibility in Idaho and the other 26 states with similar laws is settled. Athletic programs at the high school and collegiate levels in those states now have clear legal authority to enforce biological sex requirements for women’s and girls’ competitions.

The decision arrives as Idaho continues to absorb a record-setting 2026 legislative session that produced hundreds of new laws. Separately, another Idaho law tied to sex-based policy distinctions — the state’s restroom statute — faced its own court test ahead of a July 1 implementation deadline.

For Ehardt and the legislators who backed the 2020 law, Tuesday’s ruling validated a strategy that began with Idaho serving as a test case. The state’s willingness to absorb years of litigation — and the costs that came with it — ultimately produced a precedent that now shields similar laws nationwide from constitutional challenge.