The evidence does not support blanket bans on trans women in sport. Studies show trans women on hormone therapy have testosterone levels at or below those of cisgender women, and any performance advantage diminishes significantly over time. Current bans are driven more by political pressure than by peer-reviewed science.
Why this debate runs hotter than the evidence warrants
If you follow this topic only through headlines, you might reasonably conclude that trans women are dominating women's sport and that the science firmly backs exclusion. Neither of those things is true. What is true is that a small number of high-profile cases have been amplified enormously, framed in ways that generate outrage, and then cited as proof of a crisis that the data does not describe.
I have been watching this for years, and the pattern is consistent. A trans woman competes. She wins, or sometimes she does not even win. The story becomes enormous. The framing is almost always the same: unfair, dangerous, cheating. What you rarely see is the follow-up: the peer-reviewed research, the actual testosterone numbers, the context of how many trans women are competing at elite level and what their results actually look like across time.
So let me tell you what the evidence actually shows, and then let me say something about the legal cases that have been generating so much heat recently.
What the research on performance actually says
Trans women who have been on hormone therapy, particularly those who have been on it for any significant length of time, typically have testosterone levels lower than cisgender women. That is not a campaigning claim. That is what the physiology produces when oestrogen-based hormone therapy suppresses endogenous testosterone production over months and years.
Some studies have found that certain physical markers, things like lung capacity, grip strength, and haemoglobin levels, take longer to equalise than testosterone levels alone. That is worth knowing, and it is the basis for reasonable ongoing research into sport-specific eligibility criteria. But "takes longer to equalise" is not the same as "never equalises" and it is not the same as "always confers a decisive advantage." Those are very different claims, and they are often conflated deliberately.
What the broader body of research does not show is a consistent pattern of trans women dominating elite competition. If that pattern existed, we would see it in results. We do not see it. The number of trans women competing at elite level in women's sport is very small, and their results do not describe a group with an overwhelming and permanent advantage.
There is also a question worth asking about consistency. Cisgender women vary enormously in their natural testosterone levels, their muscle mass, their lung capacity, their bone density. We do not ban cisgender women whose natural physiology sits at the top of those ranges. Caster Semenya was put through years of legal proceedings because her naturally occurring testosterone was deemed too high. That case, and others like it, tells us something important about who sport is comfortable with and who it is not. The science is being applied selectively, and the selection is not neutral.
The SJSU volleyball case and the wrestling lawsuits
Recent legal cases in the United States have become focal points for this debate, and they deserve careful reading rather than the summary version that circulates on social media.
The San José State University volleyball controversy centred on a trans woman player whose participation opponents argued was unsafe and unfair. Competing teams forfeited matches rather than play against her. The framing in much of the coverage was that her presence was self-evidently dangerous and that her opponents were simply protecting themselves. What was rarely examined in that framing was the actual evidence of harm, or the fact that forfeiting is itself a political act, not a measured safety response.
Wrestling lawsuits in various US states have raised similar arguments: that trans women competing in women's categories creates an unfair and unsafe environment. These cases have attracted significant political support and media attention, and they have been used to justify legislative bans on trans athletes in multiple states.
What these legal challenges have not done is establish, on the evidence, that trans women competing under hormone therapy eligibility guidelines poses a proven, consistent competitive threat. The courts in these cases have been navigating political and procedural questions as much as scientific ones. Hostile framing and high engagement do not make something true, and a lawsuit is not a study.
What the Supreme Court ruling did and did not say
There has been a great deal of misunderstanding and deliberate misinformation about the UK Supreme Court's ruling in For Women Scotland Ltd v The Scottish Ministers, and I want to be clear about what it actually decided, because the same principles I discussed in the context of Sandie Peggie's case apply here too.
The Supreme Court interpreted the Equality Act 2010 as meaning that the terms "woman" and "sex" in that Act refer to biological sex for the purposes of the Act. It found that a Gender Recognition Certificate does not bring a trans woman within the Act's definition of "woman" for equality law purposes.
That is a significant and contested interpretation. Many legal commentators, equality organisations, and human rights advocates argue it is inconsistent with what Parliament intended when it passed both the Gender Recognition Act 2004 and the Equality Act 2010. I think they are right about that.
But here is what the ruling did not say. It did not say that trans women can be excluded from all women's spaces. It did not say that sporting bodies must ban trans women. It did not remove legal protections from trans people. The Court was explicit: trans people remain protected under the Equality Act through the protected characteristic of gender reassignment. Discrimination against trans people on the basis of their trans identity remains unlawful.
The ruling interpreted one part of one Act. It did not rewrite sport's eligibility rules, it did not speak to medical care, and it did not say that trans women ceased to be women in any meaningful social, cultural, or personal sense. Anyone telling you otherwise is either confused or misrepresenting what the judgment says.
Who is asking "is this fair?" and who is being asked to pay for it
There is a question underneath all of this that rarely gets asked directly: fair to whom, and at what cost?
Trans girls and women who want to play sport are not asking for special treatment. They are asking to participate in the same way their peers do. The overwhelming majority of them are not competing at elite level. They are playing school sport, recreational leagues, community teams. They are doing what sport is supposed to do for everyone: building fitness, friendship, belonging, joy.
When we build policy around the hypothetical elite case, we exclude real people from ordinary life. And when that exclusion is driven by political pressure rather than evidence, it is not fairness. It is discrimination wearing the language of fairness.
The question of whether specific eligibility criteria are appropriate at the highest competitive levels is a legitimate one, and it deserves honest, evidence-based answers. Governing bodies working through that question carefully, transparently, and with input from trans athletes and scientists, is reasonable. Blanket bans justified by misinformation and political momentum are not the same thing, and they should not be treated as though they are.
What governing bodies are actually permitted to do
In the UK, sport is one of the areas where the Equality Act 2010 does permit some differential treatment on the basis of sex, where this is necessary for reasons of safety or fair competition. That provision exists and it is real. It does not, however, require exclusion: it permits it, in specific and limited circumstances, where the evidence supports it.
Governing bodies that use this provision to enact blanket, evidence-free bans are not following the law carefully. They are using a legitimate legal space to do something the evidence does not justify. That is a different thing, and it matters that we name it as such.
Trans athletes deserve to have the same evidence standards applied to decisions about their participation as are applied to any other eligibility question in sport. Not higher standards, not lower standards, the same standards. Right now, in much of this debate, that is not what is happening.
If there is a topic that you would like me to cover, just let Sammy know.
Dr Helen Webberley is a Gender Specialist, Medical Educator, writer, and advocate, and the founder of GenderGP. She works in advocacy, education, and public engagement, promoting understanding of gender diversity.
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