Scarinci: Only Biological Sex” matters in the UK

In ruling that the term “sex” should be understood to refer solely to “biological sex,” i.e. the sex as originally recorded on a person’s birth certificate, the U.K. Supreme Court claimed to be providing legal clarity. However, like many landmark legal decisions, its ruling is proving to be both controversial and challenging to implement.

UK Decision

In For Women Scotland v. The Scottish Ministers, the U.K. Supreme Court unanimously held that the terms “woman” and “sex” in the 2010 Equality Act refer to a biological woman and biological sex. Accordingly, a trans woman is a biological man, and a trans man is a biological woman for the purposes of the statute.

“Interpreting ‘sex’ as certificated sex would cut across the definitions of ‘man’ and ‘woman’ … and, thus, the protected characteristic of sex in an incoherent way,” Justice Patrick Hodge stated, summarizing the court’s rationale. “It would create heterogeneous groupings.”

The legal challenge arose from 2018 law passed by the Scottish Parliament requiring 50 percent of the membership of the boards of Scottish public bodies to be women, with transgender women with gender recognition certificates included in meeting the quota.

Prior to the decision, the term “sex” under the Equality Act 2010 was understood to include transgender individuals who had obtained a Gender Recognition Certificate. Under the Gender Recognition Act 2004 (GRA), after acquiring a certificate, a trans person’s sex becomes their acquired sex (the sex they have transitioned to) “for all purposes.”

The U.K. Supreme Court agreed with challengers that, under the Equality Act, “sex” should refer to biological sex as understood “in ordinary, everyday language.” The decision only affects protections under the Equality Act. However, it means that trans women can now be excluded from some groups and single-sex spaces, such as changing rooms, homeless shelters, hospital wards, and medical or counseling services provided only to women. As set forth in the court’s opinion, trans men could be excluded from women’s facilities “where reasonable objection is taken to their presence, for example because the gender reassignment process has given them a masculine appearance or attributes to which reasonable objection might be taken” in the context of a women-only service.

Much like in the United States, the UK Parliament is free to amend the Equality Act if it disagrees with the decision or wants to provide greater clarity. In the meantime, public agencies across the UK are rushing to publish guidance on what changes businesses, employers, sports organizations, schools, hospitals, and other entities should be making to comply.

The challenges of implementing the UK Supreme Court’s decision are apparent in interim guidance issued by the Equality and Human Rights Commission (EHRC). It advises that in places like hospitals, shops and restaurants, “trans women (biological men) should not be permitted to use the women’s facilities.” But, at the same time, it also states that trans individuals should not be left without any facilities to use.

Transgender Rights on this Side of the Pond

The United States is also grappling with legal and political issues related to transgender rights and gender definitions. Over the past several years, Republican-controlled states have been banning gender-affirming care for minors, banning transgender women and girls from competing in sports that align with their gender, and restricting which public bathrooms transgender people can access.

Since taking office, President Donald Trump has made several policy reversals impacting transgender rights. This includes executive orders defining the sexes as only male and female, defunding gender-affirming medical care for transgender youth, prohibiting trans individuals from enlisting and serving in the military, and banning transgender women and girls from participating in female sports.

The majority of the executive orders have resulted in lawsuits, which are winding their way through the courts. The U.S. Supreme Court already has a landmark legal challenge involving transgender/gender issues on the docket. In December, the justices heard oral arguments in U.S. v. Skrmetti, which challenges a Tennessee law banning gender-affirming hormonal therapies for transgender youth. The justices have been asked to determine whether the ban violates the Equal Protection Clause of the U.S. Constitution. A decision is expected in the late spring or early summer of 2025.