Transgender swimmer Lia Thomas taking legal action against World Aquatics

The US swimmer Lia Thomas, who rose to global prominence by becoming the first transgender athlete to win a NCAA college title, is taking legal action in a bid to compete again in elite female sport – including the Olympics.

Thomas has not swum since World Aquatics introduced new rules in 2022, which prohibit anyone who has undergone “any part of male puberty” from the female category. Before then, transgender women were able to compete if they lowered their testosterone levels.

In a scientific policy document that informed its decision, World Aquatics said that swimmers such as Thomas retained significant physical advantages – in endurance, power, speed, strength and lung size – from undergoing male puberty, even after reducing their testosterone levels through medication.

Thomas, who was a moderate swimmer in the male category before transitioning, has now recruited the Canadian law firm Tyr to take a case to the court of arbitration for sport in Switzerland. However, because the 25-year-old is not currently registered with US swimming, it is understood that the case is highly unlikely to be heard before the Paris Olympics.

The move, revealed by the Daily Telegraph, is the latest twist in the fractious debate between those who argue that fairness and safety in women’s sport is paramount and others who maintain that the inclusion of transgender athletes should be prioritised.

Thomas has always denied transitioning to get ahead. “The biggest misconception, I think, is the reason I transitioned,” Thomas said in 2022. “People will say: ‘Oh, she just transitioned so she would have an advantage, so she could win.’ I transitioned to be happy, to be true to myself.”

In a statement on Thursday, the World Aquatics’ executive director, Brent Nowicki, defended its gender inclusion policy, saying it “was rigorously developed on the basis of advice from leading medical and legal experts, and in careful consultation with athletes”.

“World Aquatics remains confident that its gender inclusion policy represents a fair approach, and remains absolutely determined to protect women’s sport,” he added.

Thomas is yet to comment, but whatever happens next will be watched closely by other governing bodies. In recent years rugby, athletics and cycling have been among those sports to toughen their rules, and a victory for Thomas would leave them open to legal challenges.