Legal definition of ‘woman’ in the context of the Equality Act clarified by the UK Supreme Court

By Alec Colson

Partner – Head of Employment

29 April 2025

Insights News

The Supreme Court has now handed down its judgment in what can only be described as a landmark decision ruling that the definition of ‘woman’ in the context of the Equality Act 2010 (‘the Act’) should be read as biological woman. This article looks at the decision made by the Supreme Court in For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16 and its impact on employers.

Facts of the case

To encourage greater representation of women on public authority boards, the Scottish Parliament introduced legislation and statutory guidance in 2018 aiming for 50% of non-executive board members to be women. In defining what a ‘woman’ was, the Scottish Parliament included transgender women as women.

After a successful judicial review initiated by For Women Scotland Ltd (FWS), the Scottish Parliament issued updated guidance clarifying that the term ‘woman’ should be understood in line with its definition under the Act. The guidance also stated that individuals holding a Gender Recognition Certificate (GRC) designating their gender as female should be regarded as women in this context. A GRC is a document that allows trans people to change their gender legally. According to the Gender Recognition Act 2004, a person who has been granted a GRC confirming their acquired gender as female is legally recognised as having the sex of a woman.

FWS challenged the Scottish minster’s guidance and brought a second judicial review against them on the basis that the definition of a ‘woman’ was outside their legislative competency. FWS argued that a ‘woman’ under the Act refers to biological sex and therefore, does not include trans women with a GRC.

Both the Outer House and the Inner House of the Court of Session found that the revised statutory guidance was lawful, determining that the definition of sex was not confined to biological or birth sex. FWS subsequently appealed to the Supreme Court.

The decision

In its unanimous decision, the Supreme Court allowed the appeal and held that the terms ‘woman’, ‘man’ and ‘sex’ under the Act refer only to biological sex and does not extend to certified sex. This means a ‘woman’ is a person born female and a ‘man’ is a person born male under the Act. Therefore, the guidance issued by the Scottish ministers was deemed incorrect. A person with a GRC does not fall within the definition of ‘woman’ and does not count towards the goal set in the gender representation objective for public sector boards.

Reasoning behind the decision

The Supreme Court, firstly, identified the importance of the Act being interpreted in a clear and consistent way so that groups which share a protected characteristic can be identified by those that the Act imposes obligations on to allow them to perform those obligations in a practical way.

Moreover, they considered that the provisions concerning sex discrimination would be unworkable unless the terms ‘man’ and ‘woman’ were defined by reference to biological sex. They specifically highlighted sections on pregnancy and maternity, noting that, biologically, only women are capable of becoming pregnant.

In its judgment, the Supreme Court firmly rejected the notion that the terms ‘woman’ and ‘sex’ could bear different meanings within different sections of the Act—biological sex in some provisions and certified sex in others. The Supreme Court underscored the necessity of a consistent interpretation throughout the Act to avoid practical complications in its application.

A key concern highlighted by the Supreme Court was that accepting certified sex within the definition would effectively create two sub-categories among those with the protected characteristic of gender reassignment: individuals with a gender recognition certificate, and those without. Such a distinction, the Court noted, would result in unequal rights within the same protected group, despite the fact that the majority of transgender individuals do not possess a GRC.

They also observed that this approach would place those bound by the Act’s obligations in a difficult position. Without a lawful mechanism to ascertain whether an individual holds a GRC—and with direct inquiry not permitted—employers and service providers would face considerable uncertainty in determining how to fulfil their duties.

In making its decision, the Supreme Court emphasised that the ruling should not be interpreted as a victory for any particular group in society at the expense of others. They highlighted that the law continues to protect transgender individuals from unlawful discrimination based on the protected characteristic of gender reassignment, as well as against direct and indirect discrimination and harassment in their affirmed gender.

Impact on employers

The Equality and Human Rights Commission (EHRC) have now released a brief interim update outlining the primary impacts of the judgment. It reminds employers it is mandatory to provide adequate single-sex toilets, as well as sufficient single-sex changing and washing facilities where needed. The main message is that trans women (biological men) should not be allowed to use women’s facilities, and trans men (biological women) should not be allowed to use men’s facilities, as this would undermine the single-sex nature of these spaces.

In light of the decision, employers will need to revisit their policies, procedures and training to ensure they accurately represent the new position. Employers should maintain a commitment to treating all employees, including transgender individuals, with dignity and safeguarding them from discrimination and harassment. They should consider the potential effects of the decision on trans people and may want to reaffirm their dedication to diversity, equity, and inclusion for all staff.

The EHRC will be updating their Code of Practice by the end of June following a 2 week period of public consultation from mid- May. We will be keeping our clients informed as further guidance is produced.

In the meantime, if you require further advice on these issues, or any other employment law matters, please contact Taylor Walton’s employment team here.

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