Dear Sir Kier Starmer, your government has the power and responsibility to protect marginalised people

Dear Sir Kier Starmer,

As psychological professionals, we the undersigned are writing to you to express our deep concern over the recent Supreme Court ruling regarding the legal definitions of “women” and “men”.

Human rights are central to our work as psychological professionals. Human rights have always been central to your work too. We hope that you believe as strongly as we do that we should use our voice to stand up for marginalised people and do our best to make the world a more just and fairer place.

This is why we were shocked and saddened by your recent statement that trans women are not women. You have referenced the recent Supreme Court ruling in this, a ruling which is deeply concerning to us.

In For Women Scotland v The Scottish Ministers (2025), the Supreme Court ruled that the legal definition of “women” and “men” refers to “biological sex”. The Equality and Human Rights Commission have taken this even further with the publication of their interim guidance, recommending that trans women be excluded from women’s spaces and trans men be excluded from men’s spaces.

As psychological professionals, we are concerned that these recent changes are psychologically harmful and scientifically unjustified. We are angered that transgender people are being used as a political football and that longstanding protections of marginalised groups are being stripped away overnight.

LGBTQ+ people already face prejudice and discrimination, with extensive research highlighting that they have poorer mental health outcomes than their cisgender heterosexual counterparts. Trans women in particular face disproportionately high levels of violence and hostility from intimate partners and members of the public. Legal protections for these vulnerable groups are essential to maintaining their safety. Furthermore, this recent ruling and ERHC guidance have a very real impact on the safety and wellbeing of cis women, the very group who they are claiming to protect.

Legally defining “women” and “men” according to “biological sex” is not only contradictory to existing law, it is scientifically unfounded. The British Medical Association’s Resident Doctors Committee further described this ruling as “scientifically illiterate” in their April 2025 conference. Trans people are at particular risk of both physical and psychological harm from these recent decisions, yet the impact is not limited to trans people. As well as discriminating against trans people, it ignores the very existence of intersex people and puts cis women at risk. The existence of intersex people, who do not fit neatly into categories of “biologically male” or “biologically female”, is not acknowledged, nor catered for. Any cis woman will be at risk if they are perceived as masculine in some way, with some lesbians likely to be disproportionately affected.

The ERHC guidance notably excludes consideration of the needs of transgender people. It states that public bodies must provide “single-sex” spaces such as changing facilities, which exclude trans people from any space appropriate for their gender. This puts trans men and women at risk of being verbally or physically attacked when using a facility that does not match their gender. The EHRC guidance does not place a duty on public bodies to cater to the needs of trans people in their provision of such facilities – this is despite the fact that gender reassignment is also separately a protected characteristic under the Equality Act (2010).

This guidance is also unenforceable in practice. It is impossible for any person to know another person’s biological sex by simply observing. It encourages unnecessary policing of the way people look and the way in which they express their gender. Not only does this guidance put trans women at risk by forcing them into men’s spaces, it also puts cis women at risk. It encourages a climate where people are discriminated against based purely on their observable features – thus a cis women who has so-called masculine characteristics may be questioned, harassed or even attacked based on this. Such a climate of distrust will have a negative impact on the mental health and wellbeing of all people.

We ask you the following:

Firstly, how can you justify the position that trans women should be excluded from women’s spaces, and trans men excluded from men’s spaces – a position which puts both trans people and cis women at risk?

Secondly, how will you ensure that the needs of trans people, who fall under the protected characteristic of gender reassignment in the Equality Act (2010), are considered and met under law and legal guidance?

Finally, how will you ensure that the Supreme Court ruling will not be misused to overrule all existing equality law that protects trans people, LGBTQ+ people and all women?

We hope that the current direction of travel and scaling back of minorities’ human rights scares you just as much as it scares us. We are keen to hear your response and hope that you will choose to stand on the right side of history when it comes to trans rights, LGBTQ+ rights and the rights of all women.

Yours sincerely,