Supreme Court rules on the definition of "sex" under the Equality Act 2010

The Supreme Court, on 16th April 2025, handed down a significant ruling on the definition of “sex” within the Equality Act 2010.

This judgement came on the back of a long-fought dispute between campaign group For Women Scotland (FWS) and the Scottish government dating back to the introduction of the Gender Representation on Public Boards (Scotland) Act 2018.

In essence the subject of the issue was how the Gender Recognition Act 2004 interplays with the Equality Act 2010 when it comes to the definition of the terms “sex”, “women”, and “man”. For clarity, in the Equality Act, sex refers to the biological meaning, whereas the Gender Recognition Act states that a Gender Recognition Certificate (GRC) changes someone’s sex “for all purposes”.

The judgement

The unanimous decision of the court was that the terms “man”, "woman", and "sex" in the Equality Act 2010 refer to biological sex.

It’s important to remember that this judgement only specifically covers the definition of these terms in the Equality Act. As the judgement notes, it is not intended to weigh in on the arguments in the wider public domain on the meaning of gender or sex. To come to their conclusion, the Court had to consider the interpretation of both Acts in practice. In short, the judgement found the following:

• The Gender Recognition Act 2004 allows for the rule that a GRC changes someone’s sex “for all purposes” to, explicitly or implicitly, be disapplied by provisions in other acts or legislation.
• The meaning of “sex” within the Equality Act 2010 needs to be consistent throughout and amongst other things, allowing certificated sex would blur the lines of the definitions of “man” and “woman, making the protected characteristic of sex incoherent.
• Allowing a certificated sex interpretation would create two sub-groups for those who share the protected characteristic of gender reassignment, with those with a GRC having greater rights than those who don’t.

Consequently, they concluded that any other interpretation of the terms “sex”, “man”, and “woman” other than biological in the Equality Act would render the Act incoherent and impracticable to operate.

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What does this mean?

When it comes to interpreting the law, any clarification provided by the courts is welcome. However, the key takeaways here are:

• The definition of “sex” within the Equality Act has been confirmed to refer to biological sex,
• This does not remove protection from discrimination for transgender people, with or without a GRC. Transgender people are still protected under the Act through the protected characteristic of gender reassignment, and against other forms of discrimination relating to their acquired gender.

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What types of discrimination are there?

The ruling by the court has an impact on access to single-sex spaces for transgender people. From an HR perspective, organisations will need to consider what this means for their toilet facilities and other similar arrangements like shower rooms etc. Once a proportionality assessment has been conducted, the ruling means transgender people can be excluded from single-sex spaces based on their biological sex.

However, organisations must still ensure all employees – including transgender people – have access to appropriate facilities and are able to work in an environment free from harassment.

The Equality and Human Rights Commission (EHRC) are currently reviewing their guidance for organisations and the statutory code of practice on this which is expected to be available before summer 2025