Lia Thomas’s lawsuit challenging her exclusion from Olympic-level swimming was dismissed by the Court of Arbitration for Sport in June 2024, ending her path to the Paris Games without any ruling on whether the World Aquatics eligibility policy that blocked her is actually lawful. The panel found she lacked standing to bring the case at all.
Why Thomas Went to Arbitration
Thomas became the first openly transgender woman to win an NCAA Division I title when she took the 500-yard freestyle at the 2022 championships in Atlanta, finishing in 4:33.24.1Penn Athletics. Lia Thomas Wins 500 Free at NCAA Championships Three months later, the international governing body for the sport closed the door on any Olympic future.
On June 19, 2022, member federations of what was then FINA (now World Aquatics) approved a new gender inclusion policy by a 71.5 percent vote. It took effect the next day.2World Aquatics. Press Release: FINA Announces New Policy on Gender Inclusion To compete in the women’s category, a transgender woman must not have experienced any part of male puberty beyond Tanner Stage 2, or before age 12, whichever is later. The alternative routes require complete androgen insensitivity or continuous suppression of testosterone below 2.5 nmol/L from that early stage.3World Aquatics. Policy on Eligibility for the Men’s and Women’s Competition Categories
In practice, the policy bars virtually all transgender women who went through male puberty from elite women’s swimming. World Aquatics justified the rule by citing scientific findings that male puberty confers lasting advantages in muscle function, bone structure, and cardiovascular capacity that hormone therapy cannot fully reverse.4PBS NewsHour. World Swimming’s Governing Body Adopts New Rules for Transgender Athletes Thomas, having gone through male puberty before her transition, could not qualify under any of the routes.
The Case at the Court of Arbitration for Sport
On September 6, 2023, Thomas filed a request for arbitration with the Court of Arbitration for Sport in Lausanne, Switzerland. Represented by the Canadian firm Tyr LLP, she argued the rules were “invalid, unlawful and discriminatory,” violating the Olympic Charter, the World Aquatics Constitution, the European Convention on Human Rights, and the Convention on the Elimination of All Forms of Discrimination Against Women.5Court of Arbitration for Sport. CAS 2023/O/10000 Thomas v. World Aquatics
World Aquatics did not defend the substance of the policy. Its lawyers instead argued Thomas had no right to bring the case. She was no longer a member of USA Swimming when she filed. She had not applied to register for any World Aquatics event in the women’s category. And she had not met the qualifying standards that would even trigger the policy. In the federation’s view, the rules only activate once an athlete is a federation member, has established eligibility nationally, hits qualifying times, and is formally registered for a competition. None of those applied to Thomas.5Court of Arbitration for Sport. CAS 2023/O/10000 Thomas v. World Aquatics
The Dismissal
The three-member panel, chaired by Carmen Núñez-Lagos and including Richard McLaren and Ulrich Haas, agreed to split the standing question off from the merits. After a hearing on March 11, 2024 limited strictly to that procedural issue, the panel dismissed the case in an award dated June 10, 2024. It held that Thomas was “not sufficiently affected by the rules” to challenge them, because she had not registered for any World Aquatics competition and was not a current USA Swimming member.6CBS News. Lia Thomas Transgender Case Dismissed
The panel never touched the question of whether the policy is discriminatory. The consequence for Thomas was immediate: no entry into the qualifying pipeline for the 2024 Paris Olympics.7NBC News. Lia Thomas Loses Legal Battle, 2024 Olympics Hopes Dashed The World Aquatics policy stayed in place, its substance untested.
The Title IX Lawsuit Against Penn and Others
While Thomas was fighting to open the elite women’s category, three of her former Penn teammates went to court to close it. On February 4, 2025, Grace Estabrook, Ellen Holmquist, and Margot Kaczorowski filed Estabrook v. The Ivy League Council of Presidents, docket 1:25-cv-10281, in the U.S. District Court for the District of Massachusetts. They sued the University of Pennsylvania, Harvard University, the NCAA, and the Ivy League Council of Presidents.8Civil Rights Litigation Clearinghouse. Estabrook v. The Ivy League Council of Presidents
The plaintiffs alleged Title IX violations tied to Thomas’s participation in the 2022 Ivy League women’s championships. They claimed Holmquist was displaced from the championship roster, that defendants ran a “pressure campaign” to keep Thomas eligible, and that Harvard failed to provide separate locker room facilities as the championship host.9The Harvard Crimson. Swimmers Sue Harvard Over Trans Athletes They sought damages for emotional distress and asked the court to vacate Thomas’s 2022 records.10CNN. Former UPenn Swimmers File Lawsuit Over Lia Thomas
On July 29, 2025, Judge William G. Young dismissed the claims against Harvard and the Ivy League Council, finding no precedent for aiding-and-abetting liability under Title IX and no viable claim of deliberate indifference to harassment. The case against Penn and the NCAA survived but was stayed pending resolution of Gaines v. NCAA, a separate lawsuit raising similar issues, under the first-to-file rule.8Civil Rights Litigation Clearinghouse. Estabrook v. The Ivy League Council of Presidents Thomas is not a defendant in that case.
How the Legal Ground Has Shifted Since the CAS Ruling
NCAA Reversal
On February 5, 2025, President Trump signed an executive order titled “Keeping Men Out of Women’s Sports,” directing the Department of Education to amend Title IX to exclude transgender women from women’s athletics and threatening to withhold federal funding from noncompliant schools.11Williams Institute, UCLA School of Law. Impact of Trans Sports Ban Executive Order The next day, the NCAA Board of Governors barred all student-athletes assigned male at birth from competing on women’s teams, regardless of hormone therapy or prior eligibility review. Such athletes may still practice with women’s teams and receive medical care, but cannot compete or receive women’s athletic scholarships. No waivers exist, and amended birth certificates do not create an exception.12NCAA. NCAA Announces Transgender Student-Athlete Participation Policy Change NCAA President Charlie Baker told a Senate hearing in December 2024 that among more than 500,000 NCAA participants, he was aware of fewer than ten transgender athletes.13ABC News. NCAA Transgender Participation Policy in Response to Executive Order
Skrmetti and What the Supreme Court Signaled
On June 18, 2025, the Supreme Court decided United States v. Skrmetti, upholding Tennessee’s ban on puberty blockers and hormones for minors with gender dysphoria by a 6-3 vote. Chief Justice Roberts wrote that the law classifies by age and medical use, not sex, and therefore survives rational-basis review.14Supreme Court of the United States. United States v. Skrmetti, No. 23-477 Although the case concerned healthcare, the majority’s statement that biological differences between men and women “exist and matter” was read as a signal on sex-based classifications in sports as well.15SCOTUSblog. Skrmetti: The Supreme Court Reaffirms That Biology Matters
Sports Cases at the Supreme Court
The Court heard oral arguments on January 13, 2026 in Little v. Hecox and West Virginia v. B.P.J., which challenge state laws in Idaho and West Virginia barring transgender women and girls from competing on teams matching their gender identity. Based on the questioning, the Court appeared likely to uphold the bans. Justice Gorsuch argued that when Title IX was enacted in 1972, “sex” would have been understood as biological sex. Justice Kavanaugh cautioned against “constitutionalizing a rule for the whole country” given scientific uncertainty.16SCOTUSblog. Supreme Court Appears Likely to Uphold Transgender Athlete Bans A decision has not been issued.
Semenya and the Standard for Reviewing CAS Awards
On July 10, 2025, the European Court of Human Rights’ Grand Chamber ruled 15-to-2 in Semenya v. Switzerland that Switzerland violated Caster Semenya’s right to a fair hearing because the Swiss Federal Supreme Court failed to rigorously review a CAS award upholding World Athletics’ rules on athletes with differences of sex development. The Grand Chamber held that when CAS arbitration is mandatory and fundamental rights are at stake, national courts must conduct “in-depth judicial review commensurate with the seriousness of the personal rights at issue.”17Strasbourg Observers. Examining Grand Chamber’s Ruling in Semenya v. Switzerland The court did not review the substance of the World Athletics rules themselves, but commentators believe the heightened review standard could affect any renewed challenge to transgender eligibility policies issued by Switzerland-based sports federations.18Strasbourg Observers. A Human Rights Analysis of Semenya and Its Potential Effects on the Rights of Transgender Athletes For any future Thomas challenge, that route runs through Swiss courts, not the CAS panel that dismissed her.
Where Thomas Is Now
Thomas has not competed in swimming since the 2022 NCAA Championships. After graduating from Penn, she pursued a law degree. She was the keynote speaker at the Philly Trans Wellness Conference in September 2024 and works as a public speaker on transgender inclusion in athletics and social justice. She has called the World Aquatics policy “deeply upsetting” and “discriminatory” and has publicly stated that “trans women are women.”19The Daily Pennsylvanian. Lia Thomas Timeline