When Riley Gaines stepped into that pool at the NCAA Championships, she knew she was swimming against more than just another competitor. The former University of Kentucky swimmer found herself racing against Lia Thomas, a biological male who had transferred from the men’s team to compete against women.
That race became a defining moment in what would become a nationwide battle over the future of girls’ and women’s sports.
Now Gaines has joined 32 other current and former college athletes in filing a legal brief with the Supreme Court, explaining to the nine justices that they have been “harmed by the rules of college sports governing bodies that have authorized, and continue to authorize, men to take women’s places and share women’s locker rooms, showers and other private spaces in college sports.”
The high court is preparing to hear two pivotal cases, Little v. Hecox and West Virginia v. B.P.J., that could determine whether states can legally protect the integrity of girls’ and women’s athletics. Lower courts in both cases have struck down state laws designed to preserve female sports categories, forcing schools to allow biological males to compete against girls.
The American College of Pediatricians (ACPeds), one of the nation’s leading science-oriented medical organizations, has filed a comprehensive brief urging the justices to reverse those lower court decisions. Their message is clear and backed by extensive research:
“When males compete in female categories, girls predictably lose roster spots and scholarships, face unequal competition, and in some sports bear higher injury risk.Those are real medical and developmental harms to minors.”
Dr. Michelle Cretella, executive director of ACPeds, emphasized in the brief that “sex is not assigned, and it cannot be changed. It is a stable biological reality, and grounding athletic classifications in that reality is necessary to maintain fairness.” The organization reminded the justices that biological sex is “an immutable and objectively verifiable trait” and that “transitioning to a different sex is biologically impossible.”
The medical evidence supporting sex-segregated sports is overwhelming. Across all athletic competitions, men outperform women by margins ranging from 10% in swimming and rowing to over 50% in baseball pitching. These differences aren’t merely cultural or the result of training disparities. They’re rooted in fundamental biological realities that develop during puberty and persist throughout life.
Perhaps most significantly for current policy debates, ACPeds explained that “testosterone suppression does not eliminate male performance advantages.” Even after years of hormone treatment, male athletes retain strength and endurance levels above those of female peers. The brief states definitively that these are “athletic advantages that hormone suppression and surgeries cannot erase.”
The medical professionals noted that lower courts have made a critical error by “dismissing the well-documented physiological differences between males and females” while embracing “the unproven claim that identity and hormone use can erase sex-based advantages.” They called this approach “false,” explaining that “the evidence shows these differences are in fact sex-based, not hormone level-based, and those differences amply justify sex segregated sports and associated intimate spaces such as locker rooms.”
Four individuals who formerly identified as transgender have also filed a brief supporting states’ rights to protect girls’ sports. Billy Burleigh, KathyGrace Duncan, Laura Perry Smalts and Jane Smith described themselves as having personally experienced the harms of gender transition. They argue that states should be allowed “to protect young people from the harms of transitioning by not affirming a student’s perception as a member of the opposite sex and instead maintaining separate sports teams for girls and boys.”
Their brief highlights growing concerns about the long-term effects of gender transition interventions on young people. “Research shows that an increasing number of youth and adults are detransitioning, indicating harm and lack of efficacy of the interventions” used to chemically and surgically transition children and teenagers, they wrote.
From a Catholic perspective, these cases touch on fundamental principles of natural law and human dignity that the Church has consistently defended. The Catechism teaches that sexual identity as male and female reflects God’s creative design and cannot be altered by human intervention.
As Christ himself affirmed in Matthew 19:4, “He who created them from the beginning made them male and female.”
This isn’t merely a matter of athletic competition. The principle at stake involves whether civil law will acknowledge biological reality and the moral order, or whether it will be subordinated to ideological claims that contradict both science and natural law. Catholic teaching has long held that just laws must conform to the natural moral order rather than undermining it.
The constitutional issues are equally significant. Title IX was enacted specifically to ensure equal opportunities for female students in education and athletics. When biological males are allowed to compete in female categories, that foundational purpose is undermined. Female athletes lose scholarships, records and opportunities they would have otherwise earned.
The athletes who filed the brief with Gaines made this point powerfully, explaining that
“[T]he transgender eligibility rules of college athletic associations and conferences have system-wide discriminatory impacts on women.”
They described being “harmed by the college sports governing bodies imposing transgender eligibility rules” that prioritize gender identity over biological sex.
These cases also raise important questions about federalism and the rights of states to set policies that protect their citizens, particularly children and young women. The lower courts that struck down state protections for girls’ sports effectively removed this decision-making authority from elected state legislators and handed it to federal judges applying contested interpretations of federal law.
For parents across America, the outcome of these cases will determine whether their daughters can compete on a level playing field or whether athletic achievement will increasingly depend on competing against biological males. It affects not just elite athletes, but every girl who dreams of earning a college scholarship through sports or simply wants to participate in fair competition.
The Supreme Court has an opportunity to restore both scientific truth and constitutional balance to this contentious issue. By affirming states’ authority to maintain sex-segregated athletics, the justices can protect the rights and opportunities of female athletes while upholding the principle that law should be grounded in biological reality rather than subjective identity claims.
A copy of the amicus brief Riley Gaines joined was submitted to the Supreme Court on September 19, 2025. It is listed on the Supreme Court’s docket for case 24-38.
