Supreme Court Gender Ruling guidance explained: High court upholds biological definition of “Sex”

A recent Supreme Court ruling has clarified how “sex” is interpreted within the Equality Act 2010 in relation to single-sex services. Following a legal challenge, the High Court confirmed that, for the purposes of operating single-sex services, “woman” refers to a biological woman and “man” to a biological man.

In practical terms, where facilities are labelled “Men” and “Women”, those categories are defined by biological sex.

This clarification has generated anxiety from multiple directions. Trans, non-binary and intersex individuals and allies have expressed concern about discrimination and mistreatment. At the same time, businesses and public institutions are working to understand what the ruling requires, what remains discretionary and how to navigate this issue in a climate of heightened scrutiny.

However, importantly, it clarifies that the Court does not require service providers to police those spaces or automatically exclude trans people. Nor did it say that trans-inclusive approaches are unlawful; there is no blanket rule either way.

Instead, the Court said that single-sex spaces are allowed where they are a proportionate means of achieving a legitimate aim. In practical terms, that means you must have a sensible, lawful reason for your approach, such as protecting privacy in shared spaces, maintaining dignity in intimate settings or working within genuine building and layout constraints. It also means you must apply that approach in a way that is fair and balanced in your specific venue. 

The question is not whether you can have single-sex spaces, but whether you are going further than necessary in how you run them. If the same objective could reasonably be achieved in a less restrictive way, a court may expect you to consider it. The focus is therefore on whether your overall model makes sense and can be justified if challenged.

For leaders, this creates a layered obligation:

• As an employer, you must prevent discrimination and harassment toward staff.

• As a service provider, you must not unlawfully discriminate against customers.

• As an operator of single-sex spaces, you must be able to explain both your objective and why your approach is balanced, given your estate.

  
  

The legal position is clearer at the definitional level. But its operational implications are still developing. Guidance continues to evolve, and further scrutiny is likely. Organisations and leaders will need to review their position as interpretation evolves and advances, ensuring their approach remains appropriate to their context.