This article is based on a report originally published by Make UK.

In a landmark judgment, the UK Supreme Court has ruled that the Scottish Government exceeded its powers in attempting to redefine the term “woman” in the Gender Representation on Public Boards (Scotland) Act 2018. The decision clarifies the legal boundaries of devolved governments and has significant implications for equality law in the UK.

Background: The legal challenge

The Gender Representation on Public Boards (Scotland) Act 2018 was intended to improve the representation of women on public boards. However, it defined “woman” to include trans women individuals assigned male at birth but who live as women even if they did not hold a Gender Recognition Certificate (GRC).

Campaign group For Women Scotland challenged this definition, arguing that it conflicted with the Equality Act 2010, which lists “sex” and “gender reassignment” as separate protected characteristics. While their initial judicial review failed in the Outer House of the Court of Session, the Inner House reversed the decision, and the case was escalated to the UK Supreme Court.

The Supreme Court ruling

On 6 December 2023, the Supreme Court unanimously ruled that the Scottish Parliament had acted outside its legislative competence. The Court found that the 2018 Act effectively amended the definition of “woman” as set out in the Equality Act a reserved matter that only the UK Parliament can change.

The Court stated:

“The inclusion of those with the protected characteristic of gender reassignment within the definition of ‘woman’… changes the meaning of ‘woman’ as defined for the purposes of the Equality Act.”

The full judgment can be read here.

As a result, the definition of “woman” under the 2018 Act must now be interpreted to mean only biological women and those who have legally changed their gender via a GRC.

EHRC interim update on the legal definition of ‘sex’

Shortly after the Supreme Court decision, the Equality and Human Rights Commission (EHRC) published an interim update on its review into the definition of “sex” in the Equality Act.

This review was requested by the Minister for Women and Equalities to consider whether the Act should define sex as biological sex. The EHRC has acknowledged the legal and practical complexity of such a change, particularly its implications for single-sex spaces, data collection, and anti-discrimination protections.

The Commission stated that any future recommendation will be shaped by extensive stakeholder engagement and a detailed legal and policy analysis, with a final report expected later in 2024.

Implications for employers

This ruling and the EHRC’s ongoing review could significantly impact employers particularly in how they structure their equality, diversity, and inclusion (EDI) policies and manage issues relating to sex and gender identity in the workplace.

Employers should be cautious when drafting policies or taking positive action based on gender or sex, ensuring they remain compliant with the current legal definitions.

How Bhayani Law can help

Understanding and navigating developments in equality and discrimination law can be challenging, especially when changes in legal interpretation have practical implications for your workforce policies, recruitment processes, and organisational culture.

At Bhayani Law, we combine specialist employment law expertise with hands-on HR support to help employers stay compliant and create inclusive workplaces. Here’s how we can assist:

• Policy and document reviews – We can audit and update your existing equality, diversity, and inclusion (EDI) policies, staff handbooks, recruitment materials, and contracts to ensure they are legally compliant and reflect the latest case law and guidance.
• Bespoke HR advice – Whether you’re responding to a discrimination complaint, handling a sensitive grievance related to sex or gender identity, or making decisions about positive action initiatives, our team offers practical, commercially focused advice tailored to your business.
• Training and workshops – Our interactive training sessions cover equality law, unconscious bias, and inclusive leadership. We can deliver these sessions for managers, HR teams, or the wider workforce, either online or in person, helping you foster a culture of respect and understanding.
• Legal representation and support – If you face an employment tribunal claim related to sex or gender discrimination, or require representation in disputes involving protected characteristics, we offer expert legal support from initial response through to advocacy.
• Ongoing support through Watertight HR & Legal Retainer – Our Watertight HR packages give employers access to unlimited HR and legal advice, templates, and support, all for a fixed monthly fee. This includes guidance on complex EDI issues as they arise.

With offices across the UK, we work with organisations of all sizes and sectors from charities and SMEs to larger corporates offering flexible, affordable, and expert support when you need it most.

To speak to one of our experts or find out how we can support your organisation, call 0333 888 1360, or email us at [email protected].