A quick guide to the UK Supreme Court ruling on the legal definition of 'sex' and 'woman'

Overview

For Women Scotland Ltd (Appellant) v The Scottish Ministers (Respondent)

Lord Reed, Lord Hodge, Lord Lloyd-Jones, Lady Rose, Lady Simler

Today, Wednesday 16th April 2025, the UK Supreme Court issued its ruling following a long-running legal challenge regarding the definition of the term ‘woman’ in law, specifically when understanding the meaning and scope of the term ‘sex’ in the UK’s Equality Act 2010.

You will have noted that the Court ruled that the term “woman” exclusively refers to biological sex, issuing clear guidance following many years of confusion and interpretation of relevant legislation. In issuing its ruling, the Court aimed to clarify this definition explicitly when understanding who receives protection under the protected characteristic of ‘sex’ as well as clarity around protections in place for women (explicitly within the judgement, but notably also extended to men by default) most notably in providing single-sex spaces.

This ruling comes at a time where trans and gender-diverse people are under more scrutiny and suspicion than ever before, as well as being subject to increasing level of prejudice, hate and intolerance. However, the ruling was intended as a way of settling a long-standing and particularly complicated set of contradictions and confusion within UK legislation. This guidance should be read with that context in mind.

What does this mean?

What we can immediately interpret this ruling to mean practically is that:

• Transgender women (and men) with Gender Recognition Certificates (GRCs) are no longer recognised legally as women (or men) under the sex-based provisions and protections of the Equality Act 2010.

[NOTE: this will require some immediate remedial action from the UK Government to bring the Gender Recognition Act 2004 in line with this ruling.]

• Any initiatives (including Positive Action activities) designed to increase representation of women, including achieving targets for including women on Boards or in management positions, should consider women only on the basis of their biological sex. It should be made clear that this is not an explicit ruling by the Supreme Court.

However, with this new definition of ‘woman’ enshrined in law, anyone claiming discriminatory practice on the basis of sex against an organisation who is including trans women within their target demographics [for this type of Positive Action activity] have an increased chance of their claim being upheld.  

• Access to ‘women only spaces’ might be limited, or transgender women explicitly excluded from access to these environments in certain circumstances.  However, it should be noted that this can still only happen where there is a ‘proportionate means of achieving a legitimate aim’.

The EHRC (Equality and Human Rights Commission) currently outlines those ‘exceptions’ that allow organisations to “lawfully exclude, modify or limit” access to certain groups could be “for reasons of privacy, decency, to prevent trauma or to ensure health and safety”.

• Organisations should consider how they currently collect the demographic data of their employees, particularly in documenting the sex and/or gender of their employees. If employers are currently collecting this data only using a single category of ‘sex’ without any explicit references to ‘gender’ or other categories that record self-defined gender, they may want to consider reviewing this in light of the next ruling.

FAIRER Consulting can support you with this activity or provide guidance if you have any concerns or questions.

An Employer's responsibility

As a reminder, this ruling relates to the definition of ‘sex’ and ‘women’ in legislation and is not a direction that organisations are now lawfully entitled to discriminate, harass or victimise transgender people. Protections for transgender women (and men) still exist within the Equality Act 2010 under the protected characteristic of ‘gender reassignment’ and therefore organisations are still able (and we would encourage them) to:

• Consider and include transgender women and men in your attraction, recruitment and retention activities;
• Ensure that transgender women and men are afforded dignity at work and the right to privacy, should they choose not to disclose their transgender status. There is no legal requirement for transgender people to disclose this information and the provisions within the Gender Recognition Act 2004 still apply, particularly in its direction that employers have a responsibility to maintain the confidentiality of this information whenever it is disclosed;
• Continue to include transgender and gender-diverse people when designing and implementing wellbeing and rewards programmes and other EVP related activities or provisions. The sudden exclusion by omission of transgender people in these provisions or practices could be seen as an example of unlawful (discriminatory) practice;
• Provide a suitable working environment, free from discrimination, harassment and victimisation;
• Educate your workforce on inclusive practices and raise awareness of the value and importance of difference;
• Foster respectful curiosity within your workplaces, encouraging colleagues to increase their own awareness and understanding of transgender and gender-diverse communities and their experiences.  

Organisations are reminded that Harassment, as defined in the Equality Act 2010 is:
“…unwanted behaviour [related to a protected characteristic] which has the purpose or effect of violating someone’s dignity or which creates a hostile, degrading, humiliating or offensive environment.”

• Spoken or written abuse
• Offensive emails
• Tweets or comments on websites and social media
• Images and graffiti
• Physical gestures
• Facial expressions
• Banter that is offensive to you 

We would suggest that any workplace environment which either encourages or allows transgender employees to be subject to deadnaming, misgendering, intolerance, prejudice or exclusion as a result of an individual’s known or perceived transgender status might constitute creating an environment which does indeed violate transgender employees’ dignity or create such a hostile, degrading, humiliating or offensive environment.