Voters in Arizona, Nebraska, Washington and Colorado are considering ballot measures that would affect eligibility for girls’ and women’s school sports. The proposals differ in scope: Washington and Colorado would establish statewide sex-based participation rules, while Arizona and Nebraska would build on existing restrictions. The measures also vary in whether they cover private schools, colleges, athletic facilities or constitutional protections.
Washington’s Initiative 638 would bar students defined as biologically male from competing in girls’ K-12 interscholastic sports. Girls seeking to compete would need documentation from a health care professional verifying biological sex through reproductive anatomy, genetic makeup or naturally produced testosterone levels. Under the state’s current eligibility rules, K-12 athletes may compete according to gender identity. A no vote would leave those rules in place and would not add the initiative’s verification requirements.
Opponents, including No Hate in Washington State, say the initiative would discriminate against transgender students and could lead to invasive examinations of girls. Supporters reject that characterization, arguing sex could be established during a routine sports physical or through a cheek swab. The source reported a 64% market-implied chance of passage on Polymarket at the time it was written.
Colorado Proposition 134 would set sex-based participation requirements for school sports from K-12 through college. In general, athletes would compete on teams corresponding to their biological sex. Exceptions would allow coed teams and girls to join boys’ teams when there is no equivalent girls’ team. The proposal covers public, charter and private schools, colleges and universities, and interscholastic, intramural and school-sponsored club sports.
The measure defines females by reference to a reproductive system organized around producing ova, and males by one organized around producing sperm. Unlike Washington’s proposal, it does not specify a medical examination or doctor’s note as the means of verification. Schools would set eligibility policies, and the state education commissioner could act against districts that intentionally decline to comply. A no vote would retain the existing arrangement, under which schools, districts and athletic associations set policies subject to state and federal law.
Planned Parenthood and other opponents say Proposition 134 represents government overreach and risks invasive checks of girls. Jennifer Sey, founder of XX-XY Athletics and chair of the campaign supporting the measure, has argued that such examinations are not occurring in the 27 states that already restrict biological males from competing in girls’ sports. Polymarket put the measure’s market-implied chance of passage at 55% in the source report.
Arizona Proposition 318 would extend the state’s existing public-school sports restrictions to private schools and athletic associations, including organizations overseeing youth and college sports. It would also require athletic-related restrooms, locker rooms and other private spaces to be restricted according to biological sex as recorded on an original birth certificate. Athletes could sue schools and athletic associations that knowingly violated the law. The proposal retains protections for coed teams and would not categorically bar girls from competing on boys’ teams.
A no vote would leave Arizona’s current public-school restrictions in place without extending them to additional institutions or adding the proposed rules for private spaces. The ACLU and other civil-rights groups argue the measure targets transgender students, may prompt intrusive questions about sex and could expose schools to costly lawsuits. Supporters say it closes gaps in existing law, protects privacy and safety, and sets consistent competition rules. The source cited an 82% Polymarket-implied probability of passage.
Nebraska’s proposed constitutional amendment would prohibit biological males from competing in girls’ and women’s school sports from K-12 through college. Schools would designate teams as male, female or coed, with female teams reserved for biological females. The measure would cover public schools and colleges, as well as private institutions whose teams compete against public schools.
Nebraska already has a law restricting biological males from competing in girls’ and women’s sports. Gov. Jim Pillen signed the Stand With Women Act in June 2025. The amendment would place restrictions in the state constitution, making them harder for future lawmakers to change. A no vote would leave the constitution unchanged while keeping the existing law in effect.
OutNebraska and the Fairness for All campaign oppose the amendment, saying it discriminates against transgender students and adds constitutional restrictions despite the existing law. They also argue transgender athletes make up a very small share of the state’s population. Supporters say constitutional protection would prevent future changes to the law. The Fairness for Girls campaign says allowing biological males to compete against girls raises safety concerns and can affect medals, advancement and scholarships. The source reported no Polymarket prediction for Nebraska.
