The roiling debate over transgender Americans’ place in society stands on the precipice of what could be a crucial legal reckoning. On Tuesday, the Supreme Court will hear oral arguments regarding lawsuits challenging a pair of state laws that restrict student athletes from participating in sports specifically for girls or women.

Depending on a host of in-the-weeds legal factors, including whether one case is moot and whether the justices will send either case back to a lower court, the justices could issue a landmark ruling that establishes a precedent for how sex is defined under federal law with respect to gender identity. Legal experts tell the Sun such a decision could have sweeping implications for whether laws may rely on biological-sex-based segregation in environments such as prisons, domestic violence and homeless shelters, bathrooms and locker rooms.

At stake is the ability of Americans who identify as transgender — a growing population currently comprising some 3 million people, according to the Williams Institute at the UCLA School of Law — to integrate across society in accordance with their gender identities.

The cases before the Supreme Court raise critical questions about how the Equal Protection Clause of the 14^thAmendment applies to restrictions on transgender athletes competing on teams traditionally reserved for the opposite sex. The court will also be asked to consider how such laws square with the aims of Title IX, the federal law governing sex-based opportunities in education, and its associated regulations pertaining to sex-segregated sports teams. 

And after years of sidestepping the question, the court could finally determine whether transgender status itself is considered a protected class under the Equal Protection Clause, as is sex — a determination with profound implications for civil-rights law.

As this combustible and politicized issue has barreled toward a showdown before the nation’s highest court, rhetoric has hit a fever pitch. Prominent voices on each side often speak in dire and even existential terms, with transgender advocates frequently protesting that Republicans seek to erase them from public life.

For their part, Republicans have made preventing — as they put it — men playing women’s sports a major political issue, with the White House forcing colleges and universities to bar transgender women from women’s sports as a condition of receiving federal grant funds.

ACLU litigator Chase Strangio, who is transgender, said in a recent podcast interview that those pushing for the sports-ban laws have “tricked” the public “into co-opting an anti-trans narrative that is really about building fascist institutions.”

Ed Whelan, a senior fellow at the Ethics and Public Policy Center, spoke squarely from the conservative camp when he told the Sun: “These cases should decisively defeat the claim of transgender ideologues that biological males who identify as female have a federal legal right to invade facilities and teams reserved for actual females.” 

Battles Over State Bans

Multiple national polls have found that an overwhelming majority of Americans oppose transgender women playing in women’s sports. Since 2020, when the first such related ban was passed in Idaho, Republicans in just over half the states have passed laws barring biological males from the female category in school sports, and even from intramural and club athletic teams in many states. 

Liberal and LGBTQ advocacy nonprofits such as GLAAD, the Human Rights Campaign, or HRC, and the ACLU have accused conservative lawmakers of fomenting what they call a destructive moral panic over transgender student athletes. These organizations assert that this is a group of young people who comprise only a tiny fraction of the population and are already fiercely stigmatized and burdened by poor mental health.

Such advocates often point to the fact that, as of December 2024, the president of the NCAA said there were fewer than 10 NCAA players known to identify as transgender. And they claim there have been only scattered instances of transgender girls — natal males identifying as female — winning high school championships in the female category. 

“Categorically excluding kids from school sports just because they are transgender will only make our schools less safe and more hurtful places for all youth,” Joshua Block, senior counsel for the ACLU’s LGBTQ & HIV Project, said in a statement after the Supreme Court agreed in July to review the sports-restriction cases. 

According to a 2023 HRC report, 19 percent of transgender and “gender expansive” youth played sports. While this rate is disproportionately low, the Williams Institute estimates based on a federal survey conducted that same year that some 724,000, or 3.3 percent, of 13 to 17 year olds identified as transgender. This suggests that perhaps 135,000 such middle and high-school students engaged in athletics at that time. An estimated 8.3 million high schoolers participate in sports, according to the National Federation of State High School Associations. Comparable figures for middle school sports participation are less clear.

Victories by transgender females in girls’ and women’s competitions comprise a small, if apparently growing, fraction of championships, but have garnered outsize attention and scorching political scrutiny.

Most notably, University of Pennsylvania swimmer Lia Thomas became the first transgender woman to win an NCAA Division I championship in 2022 when she placed first in the women’s 500-yard freestyle and thrust this issue, and herself, into the national spotlight. Two transgender high school girls won multiple state track titles in Connecticut in the late 2010s. Female athletes displaced by Ms. Thomas and the Connecticut runners have filed lawsuits in response. Those cases are currently facing lower courts. 

The two cases going before the Supreme Court on Tuesday include a lawsuit by a transgender woman, Lindsay Hecox. Ms. Hecox has challenged Idaho’s law, signed in March 2020, that bars transgender girls and women from school sports, including at the collegiate level. Born male, Ms. Hecox, by virtue of meeting the NCAA policy at the time, took at least 12 months of estrogen to transition to female and then tried out for the women’s track and field team at Boise State University (she did not make the team). 

In the second case, a current high school student, a biological male track-and-field athlete, has sued to overturn West Virginia’s law, passed in 2021, that restricts K-12 girls’ sports according to biological sex. Known by her initials, B.P.J., in the case but identified elsewhere by the ACLU as Becky Pepper-Jackson, the plaintiff is a 15-year-old high school sophomore. Ms. Pepper-Jackson said that she started taking puberty blockers shortly after puberty’s onset and later began estrogen to instigate female puberty. Her case argues that while the state’s ban could be constitutional in some cases, as applied to the teen’s specific circumstances, it isn’t.

The 4^th Circuit Court ruled in April 2024 that West Virginia law as it applied to Ms. Pepper-Jackson violated Title IX. The 9^th Circuit ruled in June that Idaho’s law as applied to Hecox probably violates the Equal Protection Clause.

During earlier years of these cases’ litigation, transgender student athletes had the support of the Biden Administration’s education department. But deep red West Virginia and Idaho, who now have the backing of the Trump Administration, have appealed to the Supreme Court, which agreed to hear the two cases. Idaho’s defense has emphasized Equal Protection, while West Virginia’s is centered on Title IX but also invokes the 14th Amendment.

The states’ attorneys general and the conservative legal advocacy juggernaut the Alliance Defending Freedom, or ADF, are representing the states while the ACLU is representing the plaintiffs. A representative for the Trump Justice Department will also present oral argument in support of the states.

Seeking Certainty About Title IX 

At issue in policies governing athletic sex segregation is the tension between fairness and what transgender rights supporters call inclusion. Central to this are the benefits that greater exposure to testosterone affords athletes born male, and in particular the well-established and profound athletic advantages driven by male puberty. And so questions before the Supreme Court partially concern fast-evolving scientific research about whether gender-transition treatment eliminates or only partially narrows this advantage. 

There are also thorny questions about whether, in particular, a natal male athlete taking estrogen who never underwent a substantial male puberty, like Ms. Pepper-Jackson asserts about her medical history, should be considered female under athletic sex-segregation policies.

But how is “sex” defined? Is it synonymous with gender identity, perhaps only in certain contexts?

Title IX of the Education Amendments of 1972 demands that, for all schools and universities receiving federal funding, no one shall “on the basis of sex, be excluded from participation in, be denied the benefits of, or be subject to discrimination under any educational program or activity.” A subsequent 1974 amendment to Title IX instructed a federal agency to issue regulations on athletics. 

According to Doriane Lambelet Coleman, a professor at Duke Law School and the author of On Sex And Gender: A Commonsense Approach, the resulting regulation clarified that sex-segregated intercollegiate teams were a permissible means of affording women competitive fairness in both college and secondary-school sports.  

The transgender sports cases offer the Supreme Court its first opportunity to weigh in on Title IX’s application in sports, raising concerns among Ms. Coleman and other legal experts that the justices might weaken the statute.

The Justice Department’s brief supporting Idaho and West Virginia argues that nothing in Title IX and its resulting regulation permitting sex-segregated teams demands a special carve-out for transgender athletes. 

If the court were to rule that gender identity is synonymous with sex, this would help protect transgender people’s right to participate in sex-segregated sports according to their gender identity. If the court were to rule it isn’t, this would support laws barring entry into the female category in particular by athletes born male. 

Those backing the states further argue that natal males pose a safety risk to girls and women in contact sports. They also seek to defend what they characterize as the privacy rights of female athletes, in particular their access to locker rooms and showers free from people born male and from exposure to male genitalia. 

In an amicus brief, Women’s Declaration International USA stated that “we cannot protect women and girls from harmful sex discrimination, invasions of privacy, and sex-based violence unless sex can be maintained as a discrete category in the law.”

The ACLU and others who have filed briefs on behalf of Ms. Pepper-Jackson and Ms. Hecox assert that forcing an athlete to participate on a single-sex team that conflicts with their gender identity is dehumanizing and subjects them to an even greater level of stigma than they already endure for being openly transgender. And they complain that policies segregating sports based on biological sex could lead girls and women to be subjected to invasive physical inspections.

In an amicus brief that relies heavily on a legal theory that sports sex segregation is based on sex stereotypes rather than simply biological sex, the National Women’s Law Center wrote: “These humiliating ‘tests”— including requiring documentation of reproductive or menstrual history, chromosomal or hormonal testing, and genital inspections — have been weaponized against girls and women who do not meet stereotyped ideals of femininity to force them to ‘prove’ they are ‘truly’ women.”

Some assert that the threat of genital inspections is a mere fear tactic and that a routine physical from a doctor would suffice to confirm an athlete’s sex. (Others assert that expressing concern about sexual violence in locker rooms is a fear tactic.)

Emma Hilton, a developmental biologist at the University of Manchester, stated in an amicus brief that a simple cheek swab can determine a person’s sex without the need for more intrusive scrutiny in 99.9 percent of cases. 

An Allegedly Imperfect Plaintiff

Problematically for the ACLU, in an amicus brief submitted to the Supreme Court, a teammate of Ms. Pepper-Jackson’s in West Virginia, a girl known as A.C. but identified by ADF as Adaleia Cross, published a series of damning, although unverified, accusations about the transgender student’s behavior. 

In February 2023, the 4^th United States Appeals Circuit granted an injunction pending appeal of the West Virginia Law. This cleared the way for Ms. Pepper-Jackson to join a girl’s middle-school track-and-field team. At the time, Sruti Swaminathan, an attorney for Lambda Legal, which is representing the plaintiff along with the ACLU, said that “like all transgender people,” Ms. Pepper-Jackson “deserves respect and the opportunity to play sports, have fun with her friends, and just be a kid.” 

While on the girls’ team, the plaintiff made “increasingly aggressive, vile, and disturbing” remarks to Ms. Cross and other girls on the team, including in the locker room, the girl’s brief alleges. This allegedly included Becky Pepper-Jackson routinely saying, “Suck my dick” to Ms. Cross. The brief also claimed: “At times, B.P.J. told her quietly, ‘I’m gonna stick my d*** into your pu***.’ And B.P.J. sometimes added “and in your a**’ as well.”. 

Ms. Cross also complained that Ms. Pepper-Jackson’s biological sex has conferred an unfair athletic advantage over her. 

In a motion filed in 2022 by West Virginia’s attorney general seeking to dissolve the district court’s injunction allowing Ms. Pepper-Jackson to compete, they enumerated the many girls the youth had already displaced in competitive rankings. They wrote: “This broad displacement contradicts what Ms. Pepper-Jackson told the Court a few months ago—that not one ‘single person’ would be harmed by enjoining this validly enacted State law.”

The Culture War

As the youth population identifying as transgender has ballooned over the past decade, the sports inclusion issue has gained increasing salience among everyday Americans. Republicans have leveraged it as a culture-war flashpoint. 

In turn, the public has soured on transgender people participating in sports according to their gender identity. Gallup polling found that the proportion of Americans who supported such inclusion declined from 34 percent in 2021 to 24 percent in 2025, while those who opposed it increased from 62 percent to 69 percent. Those opposed in 2025 included 90 percent of Republicans, 72 percent of independents and 41 percent of Democrats. 

President Trump’s aggressive agenda to eliminate acknowledgement of transgender identity in public life has covered, among other domains, the military, education, scientific research and passports. He issued an executive order in February barring transgender females from girls’ and women’s sports. The following day, the NCAA began adhering to that directive. 

HRC president Kelley Robinson protested Mr. Trump’s move, saying: “This order could expose young people to harassment and discrimination, emboldening people to question the gender of kids who don’t fit a narrow view of how they’re supposed to dress or look.”

The Cases Before the Court                               

Before the justices even consider the questions pertaining to sports inclusion, sex and gender identity in the Idaho and West Virginia cases, they must first address a number of separate, critical legal questions.

The ACLU has argued that the Idaho case should be considered moot because the plaintiff, Ms. Hecox, has decided to refrain from further efforts to participate in collegiate sports. The court deferred its decision on that matter until the oral arguments. 

The justices also might be inclined to remand one or both of the cases back to the district courts given various unresolved questions about, for example, the standard for applying preliminary injunctions and the relevant scientific research about athletic competitiveness. This could possibly preclude any landmark decision by the high court this term.

In the Idaho case, for one, the district court accepted expert testimony that asserted that transgender women who have taken sustained testosterone suppression and estrogen treatment maintain no significant competitive advantage over women athletes. But research published in more recent years, including review papers coauthored by Dr. Hilton and other experts, has challenged such a conclusion. So the Supreme Court may return that case to the lower-level court to allow for debate on the more up-to-date science. 

Dr. Michael J. Joyner, an expert in exercise physiology and coauthor of one of the more recent review papers, told the Sun: “We summarized the clear cut evidence showing that biological males have an advantage in every key physiological domain relevant to sports performance. These advantages are not fully reversed or eliminated by testosterone suppression.”

In interviews, Dr. Joyner and other sports-physiology experts expressed confidence in such findings. These experts also questioned the validity of a recent, widely touted study conducted on behalf of the International Olympic Committee, published in 2024, that suggested that transgender women taking gender-transition treatment do not hold physiological advantages in women’s athletics in at least some domains. The critics called the study’s methodology weak and its findings unreliable. 

Whether natal males who begin gender-transition drugs immediately after the onset of puberty hold an advantage in girls’ and women’s sports remains a more open scientific question. However, Dr. Joyner’s review concluded that even prepubescent boys hold small but significant athletic advantages over girls. He and other researchers said they believe this performance gap is largely a product of males’ greater exposure to testosterone in utero and to the surge in testosterone boys experience during a short period in infancy known as mini puberty. 

In both sports cases before the Supreme Court, the ACLU has called upon the justices to define transgender people as what’s known as a quasi-suspect class under the Equal Protection Clause. If the court were to comply, laws that distinguish based on transgender status, just as with laws that distinguish based on sex, would typically have to be subjected to a heightened level of judicial scrutiny. This means the bar is higher for the law to pass legal muster by satisfying an important government interest. 

The question about trans people’s quasi-suspect-class status remained unaddressed by the landmark 2020 Bostock decision finding that Title VII of the 1964 Civil Rights Act barred employment discrimination based on sexual orientation and gender identity. Chief Justice Roberts again sidestepped the question in last year’s landmark ruling in the Skrmetti case that gave the court’s blessing to state bans of gender-transition treatment for minors. 

Legal experts frequently note the court’s steadfast reluctance to add new protected-class categories, such as homosexuality, to the short roster already positioned under the Equal Protection Clause, which includes race, religion and a few others. Additionally, Justices Thomas, Alito and Barrett already indicated in their concurring opinions in Skrmetti that they believed that transgender people did not qualify for such a classification. 

Mr. Whelan told the Sun he believed that the court’s conservative majority would determine that Idaho and West Virginia’s laws turned not on gender identity, but on sex, thus leaving transgender status out of the equation. 

If the justices do decide the state laws turn on sex, they must determine whether this demands that they apply heightened scrutiny to their constitutional review of the laws. 

This raises the question of whether each plaintiff is what’s known as similarly situated with members of their birth sex or with the sex aligning with their gender identity. If they were deemed similarly situated to females, this would trigger the heightened review demanded by sex discrimination, given they are being treated differently from that group by being excluded from teams restricted to females. If they are found similarly situated to males, this would not trigger a heightened review, given the broadly accepted purpose of the female category is to exclude males.

The attorneys for the plaintiffs have argued in briefs for the Idaho and West Virginia cases that, given Ms. Hecox and Ms. Pepper-Jackson have taken gender-transition treatments, each is more similarly situated with girls than boys. 

“Excluding transgender girls who have no physiological characteristics relevant to athletic advantage does not advance West Virginia’s asserted interest in protecting equal athletic opportunity,” the ACLU attorneys argued in their brief to the high court about the case.

Jonathan Scruggs, senior counsel and vice president of litigation strategies at ADF, told the Sun that his team will argue before the court that schools, he said, “can’t do a person-by-person evaluation in sports.” He said that team designation can only be determined more broadly by class, whether biological sex or, as in wrestling, weight class.  

Mr. Scruggs criticized the ACLU for what he characterized as its effort to redefine sex under the law. Conflating sex with gender identity, he said, “would make every definition of biological sex illegal” and unleash chaos throughout the legal system. 

If heightened scrutiny is indeed required in these cases, whether because of sex or transgender-status distinctions, then the science about sex-based competitiveness and gender-transition-treatment history will play a part in the court’s deliberations about whether excluding trans females from girls’ and women’s sports passes constitutional muster.

The lawsuit over Lia Thomas’ participation in the swimming championship, meanwhile, goes further than asking whether states may bar transgender females from girls’ and women’s sports. It asks whether Title IX, in fact, requires the NCAA to restrict sports participation according to biological sex. 

That question might reach the Supreme Court in the coming years.