Organizers of Great Britain’s version of the combined sports of swimming, biking and running — the Triathlon — have made a landmark decision to resolve the question of whether transgender women athletes can compete with other women.

On July 6, they issued a new policy that creates a new, separate category, in which transgender and nonbinary athletes can compete alongside men, women and anyone who wishes to race.

But starting Jan. 1, 2023, trans female athletes can no longer compete with cisgender women. They will be banned from entering the new female category according to the new policy, which says, “Only people who are the female sex at birth will be eligible to compete in the female category.”

American trans athlete and activist Chris Mosier was swift to condemn the shift as transphobia.

By creating a transphobic policy, British Triathlon is showing it not only tolerates transphobic behavior, it is actually leading the way. Policies that ban trans people encourage transphobia towards trans people.

— The Chris Mosier (@TheChrisMosier) July 6, 2022

British trans advocates at the Trans Legal Project said British Triathlon made the change because they believe, “all trans women are appropriately classed as men not women.”

The ‘open’ category has been created for men to compete and they will likely make up nearly 100 percent of it. It is effectively the male category. Trans women will be included in it. This is can only be because @BritTri believes all trans women are appropriately classed as men not women.

— Trans Legal Project (@TransLegalProj) July 7, 2022

While admitting that scientific research regarding trans athletes is “somewhat limited,” officials point to findings that mirror talking points argued by opponents of transgender inclusion, even citing two of the most notorious critics: Drs. Emma Hilton and Tommy Lundberg.

“The science that does currently exist strongly challenges the idea that testosterone suppression alone sufficiently removes the retained sporting performance advantage of transwomen (when compared with pre-transition and/or cis women),” say the Triathlon officials.

However, they also cite research by Joanna Harper, a trans woman working at Loughborough University in the U.K. who also happens to be a trans athlete. The study she conducted concludes that the strength of trans women remains “above that observed in cisgender women, even after 36 months” of hormonal therapy. But Harper told the Los Angeles Blade back in March that there’s more to it than that.

“Although trans women do maintain athletic advantages after hormone therapy, there is no indication that these advantages have led to an overrepresentation of trans women at any level of sports,” she wrote in an email to the Blade. “We allow advantages in sport but not overwhelming advantage of one group over another when we divide sports into categories. It appears that hormone therapy reduces the advantages held by trans women to the point where we can have meaningful competition between trans and cis women in most sports.”

Harper has several more studies into trans athletes underway. But British Triathlon isn’t waiting, and plans to put this new solution into effect come the new year. Harper explained that a “level playing field in sport is illusory,” and that sports organizers who are moving swiftly to respond to complaints about trans athletes are forgetting something important she’s found:

“Trans women do maintain advantages over cis women, but also face disadvantages because their larger bodies are now being powered by reduced muscle mass and reduced aerobic capacity. These advantages and disadvantages play out differently in various sports, but trans women are not on the verge of taking over women’s sport.”

Organizers claim they are not discriminating against trans athletes with this new policy. “British Triathlon is determined that the transgender community can access triathlon without fear of discrimination or prejudice,” they said in a statement. “People who identify as transgender have the right to be treated with dignity and respect and British Triathlon operates a zero-tolerance policy on homophobia, biphobia, and transphobia.”

Under the existing policy, which terminates on Dec. 31, trans women who are 17 and older and have medically lowered their testosterone to female levels can compete with cis women, and trans men are allowed to compete with men. Once the new categories go into effect on New Year’s Day, trans men can choose to compete in the female category or in the new open category.

Recreational triathlon events will not be impacted, according to the new policy; participants can take part in the gender matching their identity.

Read the full policy announcement by clicking here.