Sex, Gender and the Workplace: The UK Supreme Court Clarifies the Law

Last month’s Supreme Court ruling in For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16 has major implications for how UK employers approach sex-based rights and workplace policies, particularly in relation to transgender employees.

At the heart of the case was a deceptively simple legal question: when the Equality Act 2010 refers to ‘sex’, does it mean biological sex, or can it include someone’s ‘acquired gender’ if they hold a Gender Recognition Certificate (GRC) under the Gender Recognition Act 2004?

The Supreme Court has now given a clear answer: under the Equality Act 2010, sex means biological sex. All transgender indivicuals (whether or not they have a GRC) must be treated in accordance with their birth sex, for the purposes of the Equality Act 2010. 

The background

The case began as a challenge to Scottish government guidance under the Gender Representation on Public Boards (Scotland) Act 2018. That Act aimed to improve representation of women on public boards. But the guidance said that the definition of ‘woman’ included trans women with a GRC. This interpretation was challenged by feminist campaign group For Women Scotland, and the case ultimately reached the UK Supreme Court.

The decision

In a unanimous judgment, the Supreme Court held that the Equality Act 2010 uses the terms ‘man’, ‘woman’ and ‘sex’ to refer to biological sex only — not to acquired gender, even where a GRC has been granted. In doing so, the Court overturned the earlier ruling of the Scottish courts.

The Supreme Court was at pains to stress that it was not engaging in political debate. It was interpreting the law as it stands — particularly how the Gender Recognition Act 2004 (GRA) interacts with the Equality Act 2010. The key provision was section 9(1) of the GRA, which states that a person’s gender becomes their acquired gender ‘for all purposes’ once a GRC is issued.

However, section 9(3) allows this to be overridden by other laws. The Supreme Court concluded that the Equality Act is one such law.

The Justices ruled that interpreting ‘sex’ to include acquired gender would make key parts of the Equality Act unworkable, including provisions on pregnancy discrimination, single-sex services and sports.   It would also create inconsistent rights among trans people based solely on whether they hold a GRC (a confidential document employers cannot lawfully ask about).

What this means for employers

This judgment has immediate relevance for workplace policies. Key points to note include the following:

• a woman is a biological woman, and a man is a biological man, for the purposes of sex discrimination law;
• transgender individuals remain protected under the separate protected characteristic of gender reassignment, regardless of whether they hold a GRC;
• trans women cannot insist on access to women-only spaces (such as toilets or changing rooms) based on their acquired gender alone;
• employers must carefully balance the rights of trans employees with those of other employees who may expect single-sex spaces to reflect biological sex.

This is a significant clarification in an area that has seen legal and cultural uncertainty. While some policy areas remain open to challenge — and further case law is likely — employers should now:

• review equality, diversity and inclusion policies;
• revisit your approach to single-sex spaces and occupational requirements;
• take care when handling sensitive personal information, such as gender identity or gender reassignment status.

Above all, respect and sensitivity are key. Employers will need to walk a careful line, ensuring dignity and privacy for all employees while complying with what is now a clearer, if at times uncomfortable, legal framework.

If you would like help reviewing your workplace policies in light of this judgment, please get in touch with the Employment Team at Boardside Law.