The UK Supreme Court ruled that ‘sex’ in the Equality Act 2010 means biological sex only, not sex as modified by a Gender Recognition Certificate under the Gender Recognition Act 2004. A trans woman with a GRC is not a ‘woman’ for EA 2010 purposes. The Scottish Ministers’ guidance was declared unlawful.
Background
For Women Scotland Ltd (‘the appellant’), a feminist voluntary organisation, challenged statutory guidance issued by the Scottish Ministers under the Gender Representation on Public Boards (Scotland) Act 2018 (‘the 2018 Act’). The 2018 Act set a gender representation objective requiring 50% of non-executive members on certain public boards to be women. Following a successful earlier judicial review which struck down the 2018 Act’s expanded definition of ‘woman’ as outside devolved competence, the Scottish Ministers issued revised guidance in April 2022. This guidance stated that, in the absence of the struck-down definition, ‘woman’ bore the meaning given by sections 11 and 212(1) of the Equality Act 2010 (‘EA 2010’), and that by virtue of section 9(1) of the Gender Recognition Act 2004 (‘GRA 2004’), a person issued with a full gender recognition certificate (‘GRC’) in the female gender was a woman for these purposes.
The appellant contended that this guidance was unlawful because ‘sex’ in the EA 2010 means biological sex only, and a trans woman with a GRC does not fall within the definition of ‘woman’. The Outer House (Lady Haldane) and the Inner House (Second Division) both rejected the challenge, holding that section 9(1) of the GRA 2004 operated to change a person’s sex ‘for all purposes’ including for the purposes of the EA 2010, subject only to specific exceptions.
The Issue(s)
The central question was one of statutory interpretation: whether references to ‘sex’, ‘woman’, ‘man’, ‘male’ and ‘female’ in the EA 2010 are to be interpreted in light of section 9(1) of the GRA 2004 as including persons who have acquired a different gender through a GRC, or whether those terms refer exclusively to biological sex. Section 9(1) of the GRA 2004 provides that where a full GRC is issued, the person’s gender becomes ‘for all purposes’ the acquired gender. However, section 9(3) provides that subsection (1) is ‘subject to provision made by this Act or any other enactment or any subordinate legislation’.
The appeal therefore turned on whether the EA 2010 constitutes such ‘provision’ within the meaning of section 9(3) so as to disapply the general rule in section 9(1).
The Parties’ Arguments
The Appellant
For Women Scotland argued that the EA 2010 refers exclusively to biological sex. Interpreting ‘sex’ as including ‘certificated sex’ would render numerous provisions of the EA 2010 incoherent and unworkable, particularly those relating to pregnancy and maternity, single-sex services, communal accommodation, sport, positive action, and the public sector equality duty. The appellant also argued that the GRA 2004’s practical relevance had been diminished by subsequent legislation.
The Respondent
The Scottish Ministers contended that section 9(1) of the GRA 2004 applied to the EA 2010, so that a trans woman with a GRC is a ‘woman’ within the meaning of sections 11 and 212(1). They submitted that the disapplication of section 9(1) required express words or necessary implication. They accepted that in the context of pregnancy and maternity provisions, ‘woman’ might need to be interpreted as meaning biological woman, but contended that a variable definition was not impermissible.
Interveners
Sex Matters argued that ‘sex’ should be construed as biological sex. The Equality and Human Rights Commission (‘EHRC’) maintained its longstanding position that sex includes certificated sex but recognised that this caused ‘profound’ difficulties in at least four areas and called for urgent legislative reform. Scottish Lesbians, the Lesbian Project and the LGB Alliance argued that a certificated sex interpretation would create serious problems for lesbians.
The Court’s Reasoning
Statutory Interpretation Framework
The Court, in a joint judgment of Lord Hodge, Lady Rose and Lady Simler (with whom Lord Reed and Lord Lloyd-Jones agreed), restated established principles of statutory interpretation, emphasising that the court’s task is to identify the meaning of the words Parliament used, read in their statutory context. The Court underscored the constitutional importance of clarity and predictability:
Citizens, with the assistance of their advisers, are intended to be able to understand parliamentary enactments, so that they can regulate their conduct accordingly. They should be able to rely upon what they read in an Act of Parliament.
The Court emphasised the presumption that a word has the same meaning throughout an Act, which is stronger where a word is expressly defined.
Section 9(3) of the GRA 2004
The Court rejected the Scottish Ministers’ and EHRC’s submission that only express wording or ‘necessary implication’ could disapply section 9(1). The stringent necessary implication test associated with the principle of legality was held inapplicable because no fundamental common law right or constitutional right was at stake:
The stringency of the necessary implication test is not appropriate when considering the application of section 9(3) of the GRA 2004. The principle of legality described by Lord Hoffmann in R v Secretary of State for the Home Department, ex p Simms [2000] 2 AC 115, 131, is not engaged here.
The Court held that section 9(3) applies where the terms, context and purpose of the relevant enactment show a clear incompatibility or that the provisions would be rendered incoherent or unworkable by the application of section 9(1).
The Core Provisions of the EA 2010
The Court undertook a detailed analysis of the EA 2010. Section 11 defines the protected characteristic of sex by reference to ‘a man or a woman’, and section 212(1) defines ‘woman’ as ‘a female of any age’ and ‘man’ as ‘a male of any age’. The Court found that the ordinary meaning of these plain and unambiguous words corresponds with biological characteristics:
Although the word ‘biological’ does not appear in this definition, the ordinary meaning of those plain and unambiguous words corresponds with the biological characteristics that make an individual a man or a woman. These are assumed to be self-explanatory and to require no further explanation.
The pregnancy and maternity provisions (sections 13(6), 17, and 18) were identified as a strong indicator that sex means biological sex throughout, since only biological women can become pregnant. The Court stated:
The repeated references in these sections, to a woman who has become pregnant or who is breast-feeding only make sense if sex has its biological meaning.
Rejection of the Variable Definition
The Inner House had accepted that pregnancy provisions referred to biological sex but held that elsewhere the EA 2010 bore a wider certificated sex meaning. The Supreme Court firmly rejected this approach:
By its nature a variable definition is neither clear, constant nor predictable. It is the opposite in fact. It is also contradicted by the single definition of sex that fixes its meaning in the EA 2010.
Incoherence and Unworkability of a Certificated Sex Interpretation
The Court systematically demonstrated that a certificated sex interpretation would render numerous provisions of the EA 2010 incoherent or unworkable, including: separate and single-sex services (Schedule 3, paragraphs 26–28); communal accommodation (Schedule 23, paragraph 3); single-sex higher education institutions (Schedule 12); single characteristic associations and charities (Schedule 16 and section 193); sport (section 195); public sector equality duty and positive action provisions (sections 149, 158–159); and the definition of sexual orientation (section 12). The Court observed that the EHRC itself had identified eight areas where a biological sex interpretation would bring greater clarity, stating:
It is striking that the EHRC has advised the UK Government of the problems created by its interpretation of the EA 2010, which include many of the matters which we have discussed above, and has called for legislation to amend the Act. The absence of coherence and the practical problems to which that interpretation gives rise are clear pointers that the interpretation is not correct.
Protection for Trans People
The Court was careful to explain that its interpretation does not remove or diminish protections for trans people under the EA 2010. Trans people remain protected against direct discrimination (including by perception and association), harassment, and indirect discrimination (including under the extended provision in section 19A). The Court held:
A trans woman who is treated less favourably not because of being trans (the protected characteristic of gender reassignment), but because of being perceived as being a woman, will be able to claim for direct sex discrimination on that basis. This does not entail any practical disadvantage and there is no discordance … between the individual’s position in society and the ability to claim on this basis.
Practical Significance
This decision is of major constitutional and practical importance. It establishes authoritatively that ‘sex’ in the Equality Act 2010 means biological sex only, and that the GRA 2004 does not modify this meaning. This has far-reaching consequences for employers, service-providers, public authorities, sports bodies, educational institutions, charities, and associations across Great Britain. It clarifies that single-sex services, spaces and associations may lawfully be restricted to biological women (or men); that the public sector equality duty must be discharged by reference to biological sex; that positive action measures directed at women target biological women; and that trans people with a GRC do not change their sex for the purposes of sex discrimination law. The judgment preserves the distinct protected characteristics of sex and gender reassignment as separate and non-conflated bases for legal protection. It also has implications for the devolution settlement, confirming that the 2018 Act, properly construed, does not stray into reserved matters.
Verdict: The appeal was allowed. The Supreme Court unanimously held that ‘sex’ in the Equality Act 2010 means biological sex only, that the EA 2010 constitutes ‘provision’ within section 9(3) of the Gender Recognition Act 2004 disapplying the rule in section 9(1), and that the Scottish Ministers’ guidance stating that a trans woman with a Gender Recognition Certificate is a ‘woman’ for the purposes of the 2018 Act was incorrect and unlawful.
Source: For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16
