A matter of biology: the meaning of ‘man’ and ‘woman’ in today’s decision of For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16.

Image of Imogen Brown and Hana Abas

Introduction

Is the revised guidance regarding the Gender Representation on Public Boards (Scotland) Act 2018 correct? This seemingly dry question belies the seminal issues at the heart of For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16: what is a man? What is a woman? And how do trans people fit into that binary framework under the Equality Act 2010?

What started as a dispute over guidance for a relatively obscure piece of Scottish legislation passed in 2018 has expanded into an interrogation of the spirit, purpose, and aims of the Equality Act 2010. The Supreme Court decision has just been published. Here, Imogen Brown and Hana Abas explain what the judgment means, and how it will affect our practices both now and in the future.

The issues at play

The Equality Act 2010 renders it unlawful to discriminate on the basis of protected characteristics. One of those characteristics is sex, namely being a ‘man’ or a ‘woman’. Those two words are not statutorily defined, other than in the somewhat unhelpful section 212(1) Equality Act 2010: “man” or “woman” “means a male [or female] of any age”.

Under section 1(1) of the Gender Recognition Act 2004 (“the GRA”), an adult who is living in a gender different from their birth gender may apply for a Gender Recognition Certificate. Their application will be assessed by a Gender Recognition Panel, who will consider whether the person has met certain criteria, including: that they have gender dysphoria; that they have lived in their acquired gender for 2 years; and that they intend to do so until death. An application for a Gender Recognition Certificate must also be supported by medical evidence.     

Once a Gender Recognition Certificate has been issued to the individual, section 9(1) of the GRA dictates that “the person’s gender becomes for all purposes the acquired gender”. It then goes on to say that “if the acquired gender is the male gender, the person’s sex becomes that of a man and, if it is the female gender, the person’s sex becomes that of a woman”. However, section 9(3) GRA states that section 9(1) “is subject to provision made by this Act or any other enactment or any subordinate legislation”. This was referred to as a ‘carve out’ on appeal.

The process for receiving a Gender Recognition Certificate has been, and continues to be, a topic of intense public debate. It is important to stress that the Supreme Court is not deciding whether the GRA is fit for purpose, nor wading into the broader political issues at play. Its decision is concerned purely with the legal consequences of section 9(1) GRA and its interaction with the Equality Act 2010.

And so we come to the seminal issue. If an individual becomes “for all purposes” their acquired gender upon the receipt of a Gender Recognition Certificate, does that include their sex under the Equality Act 2010? Is a trans woman with a Gender Recognition Certificate a ‘woman’ under the Equality Act 2010, such that there is (for example) no lawful basis for an employer to exclude her from the women’s toilets? Or does the ‘carve out’ in section 9(3) GRA mean that the effect of a GRC is “subject” to a strictly biological interpretation of sex under the Equality Act 2010?

The decision under appeal

The Inner House of The Court of Session ([2023] CSIH 37) decided that if a trans woman obtains a Gender Recognition Certificate, she is a ‘woman’ under the Equality Act 2010: “section 9 of the GRA requires the sex of the individual for the purposes of sex discrimination to be understood to be that of the acquired gender” (see [50]). That, they held, is evidently what Parliament intended.

However, the Court of Session acknowledged the difficulties produced by their decision, holding that that in some circumstances “it may be necessary to adopt a contextual interpretation of terms such as ‘sex’ or ‘gender’ based on biology” (see [53]). For example, pregnancy and maternity discrimination provisions prohibit discrimination against a pregnant “woman”, which would remove a trans man with a Gender Recognition Certificate from important discrimination protections. Here, they said, the definition of “woman” should be expanded to also include trans men with a Gender Recognition Certificate, because “pregnancy is a matter of fact which hinges entirely on biology” (see [62]).

So, a trans woman with a Gender Recognition Certificate is a ‘woman’ under the Equality Act 2010 unless “the context clearly and necessarily dictates otherwise” (see [44]). There was little further guidance provided as to how and when the definition of ‘man’ and ‘woman’ would revert to the ‘biological’ position in certain contexts, which left some practitioners scratching their heads.

The UKSC decision

As can be imagined, the Court of Session’s decision was hotly contested on appeal. The Appellants argued that the Equality Act 2010 would be simply unworkable if a ‘man’ could become a ‘woman’ (and vice versa) upon the receipt of a Gender Recognition Certificate. The effect would be counterintuitive, in that trans men (i.e., those born as women) would be excluded from all-female spaces; positive action measures; and the protections of pregnancy and maternity discrimination provisions if they were a ‘man’ for all purposes. A pregnant trans man with a GRC could be overtly discriminated against because of their pregnancy with no recourse at all. Additionally, the Appellants argued that it would lead to the erosion of women-only spaces, such as domestic abuse refuges, if an individual born male could become for all purposes a woman and have a prima facie right to share those spaces with biological women.

The Respondents argued that the issue was a matter of simple statutory construction. The Equality Act 2010 was drafted and enacted after the GRA, and Parliament must have had the GRA in mind. Parliament could easily have drafted the Equality Act 2010 to ensure that a ‘man’ stayed a ‘man’, and a ‘woman’ stayed a ‘woman’, upon the receipt of a Gender Recognition Certificate. But they did not, and there could be no other answer to the question before the Court when construing the words of the statute.

The decision today ruled unanimously in favour of the Appellants, and overturned the decision below. Trans people with Gender Recognition Certificates are not treated as their acquired gender under the Equality Act 2010. A ‘man’ is a biological man, and a ‘woman’ is a biological woman. A GRC has no effect on a person’s sex as statutorily defined.

The judgment is long and detailed. Here are the points you need to know.

First, the Supreme Court rejected the Respondents’ contention that section 9(1) alters the meaning of ‘man’ and ‘woman’ under the Equality Act 2010 upon the receipt of a GRC. At [108], it is said that “section 9(1) […] must be carefully considered in light of the wording, context, and policy of the statute in question”. It was held that in the context of the spirit and purpose of the Equality Act 2010, section 9(3) GRA, the ‘carve out’, applies. The effect of section 9(1) is negated.

Second, it was held that reading the Equality Act 2010 as a whole, the terms ‘man’ and ‘woman’ “ can only be read coherently to mean biological sex” (see [160]). Indeed, to read the term ‘woman’ as including a trans woman with a Gender Recognition Certificate “would cut across the definition of the protected characteristic of sex in an incoherent way” ([172]). It would produce two sub-groups of trans people: those with a Gender Recognition Certificate versus those without, and their rights would be entirely different despite no material difference in their personal characteristics (see [203]). The Supreme Court could identify “no good reason” why that would have been Parliament’s intent ([172]). The protections afforded by pregnancy and maternity discrimination provisions “only make sense if sex has its biological meaning” ([178]). Further examples were analysed as to why the coherence of the Equality Act 2010 would be obviated if ‘man’ and ‘woman’ had the meaning decided by the Court below.

Third, the contention below that the meaning of sex could change where the “context clearly and necessarily requires otherwise” was overruled: “By its nature a variable definition [of ‘man’ and ‘woman’] is neither clear, constant nor predictable. It is the opposite in fact” ([191]).

Fourth, the practical difficulties of the Respondents’ contention were addressed. There is no physiological or even outward change in appearance mandated by the granting of a Gender Recognition Certificate: [202]. Thus, if the lower Court’s decision was upheld, to identify whether a trans person was a ‘man’ or a ‘woman’, an entity would have to ask them whether they had a Gender Recognition Certificate, which is a “confidential” matter ([173]). Whilst not expressly acknowledged, the Court may have had in mind that under section 22 of the GRA, it is a criminal offence to disclose matters pertaining to an individual’s Gender Recognition Certificate to others where it has been acquired in an official capacity. Put simply: employers and service providers would find it difficult to know whether an individual was a man or a woman at all, without encroaching on a trans person’s right to privacy and data protection.

Fifth, it was held that the interpretation contended for by the Respondents would entail an “inevitable loss of autonomy and dignity for lesbians […] [and] would […] have practical implications for lesbians across several areas of their lives” [207], as trans women with Gender Recognition certificates would have to be admitted to a club reserved for lesbians.

Sixth, and finally, the Court concluded with an explanation of why their decision “would not be disadvantageous to or remove protections from trans people”. Trans people, in most cases, have the protected characteristic of gender reassignment. They are protected from discrimination on that basis. Further, the Court held, trans people are also protected from discrimination based on their perceived (i.e. acquired) gender under section 13, 19A, and 26 Equality Act 2010. In other words: they do not need to be legally recognised as their acquired gender under the Equality Act 2010 in order to bring a claim if they are perceived to be that sex.

 Consequences

The decision is profound. Under the Equality Act 2010, all transgender individuals (whether or not they have a Gender Recognition Certificate) must be treated as their birth sex under the Equality Act 2010. Transgender women with a Gender Recognition Certificate have no legal right to use the women’s toilets or changing rooms at work. They have no prima facie right to undertake a job where there is an occupational requirement that the jobholder must be a woman.

Of the two ways the Supreme Court could go, it is certainly the decision which reduces uncertainty for entities subject to the obligations the Equality Act 2010 imposes. The question, however, is whether the contention that transgender individuals are adequately protected as the law stands will prove to be correct.

For practitioners, the ‘on the ground’ consequences of the decision are worth considering. For example, how does one navigate a transgender woman with a Gender Recognition Certificate, who is exclusively perceived to be a woman by those around her, being refused entry to the women’s toilets at work? To do otherwise would be to allow ‘men’ into the women’s toilets, which may result in claims from female employees that the toilets are not fit for purpose. But how would male employees feel sharing a space with an ostensibly female employee in their toilets? How would the transgender woman feel sharing that space with men, particularly when, as acknowledged by the Supreme Court, she belongs to a community that is both currently and historically vulnerable? And how does an employer deal with this issue without ‘outing’ their transgender employee to everyone else?

For now, these sorts of practical consequences remain to be litigated and considered in light of the Supreme Court’s decision. All employers and entities would be wise to review and/or revise the policies they currently have in place. A woman is a biological woman, and a man is a biological man, but the complexities of the disputes that arise day-to-day remain as complicated as ever.