28/01/2026
Written by: Hayley Webster
Background
The Scottish Parliament enacted legislation with the aim of increasing the number of women on public boards (the Gender Representation on Public Boards (Scotland) Act 2018 or “ASP 2018”). The Scottish Ministers issued statutory guidance which stated that the definition of ‘woman’ is the same as that in the Equality Act 2010 (“EA”), namely “a female of any age”, and this includes a person with a Gender Recognition Certificate (“GRC”) who has changed their legal sex to female (under the Gender Recognition Act 2004, (“GRA”)).
For Women Scotland challenged this statutory guidance arguing that the definition of ‘woman’ in the EA referred to biological females. The Scottish Ministers argued that the definition of ‘woman’ encompassed biological males with a certified sex of female.
Decision
The Supreme Court found that the words ‘man’, ‘woman’ and ‘sex’ in the EA refer to biological sex, and not certified sex.
The Supreme Court interpreted the EA and found that by necessary implication the words ‘man’ and ‘woman’ could only be read coherently to refer to biological sex and not certified sex [168-172]. The certified sex interpretation leads to real difficulties. For example, on the certified sex interpretation of sexual orientation, a lesbian would no longer be a female who is sexually oriented towards females but would be defined as a biological female or biological male with a certified sex of female, who is sexually oriented towards biological females or towards males who have a certified sex of female (but not towards females who have a certified sex of male). This would render the concept of sexual orientation as attraction towards members of the same sex meaningless [206-207].
Furthermore, the provisions relating to pregnancy and maternity must refer to biological women, as only biological women can become pregnant. If biological women with a GRC of the male gender were defined as ‘men’, for the purposes of the EA, they would be excluded from maternity and pregnancy protection. The Scottish Ministers argued that this problem could be bypassed by defining the term. ‘sex’ as’ biological sex’ in some sections of the EA and ‘certified sex’ in other sections. This would mean that trans men would be legally defined as women for maternity and pregnancy purposes, but men for other purposes. However, the Supreme Court held that the meaning of the terms ‘sex’, ‘woman’ and ‘man’ must be consistent throughout the EA otherwise the EA would become incoherent and impracticable to operate: [189-197, 264].
The impracticality of the certified sex interpretation is further highlighted by the fact that there is no perceptual distinction between a male with a GRC of female and a male who identifies as a female but lacks a GRC. Service providers would have to know if someone possessed a certificate in order to know if they were a man or woman under the EA, which would undermine the right to privacy.
Comment
Before this case was decided, it was widely believed that that a male with a GRC of female was legally regarded as a woman for all purposes (barring some minor exceptions in the GRA). This judgment has made it clear that all trans individuals (whether they have a GRC or not) must now be regarded as having their birth sex under the EA.
The practical consequences of this judgment are still being worked out. The EHRC has recently shared its updated code of practice for services, public functions and associations with the Minister for Women and Equalities for approval. It is unclear whether the biological sex interpretation extends to other legislation such as the Workplace (Health, Safety and Welfare) Regulations 1992 which provides for single sex toilets for men and women in the workplace. Recently, For Women Scotland took fresh action against the Scottish government over policies that it says are inconsistent with the Supreme Court’s judgment (such as the policy that trans women prisoners may be admitted into a female prison if there is no basis to suppose the inmate could pose an unacceptable risk of harm). The impact of this case, and the debate it has generated, is sure to reverberate for many years to come.
Matrix members
For the Appellant: Aidan O’Neill KC
Intervener- Scottish Lesbians, The Lesbian Project, LGB Alliance; Karon Monaghan KC
Intervener – Amnesty International UK: Sarah Hannett KC, Raj Desai, Roisin Swords-Kieley