Rethinking Sex Equality rights in the Age of Gender Self-determination: A critical analysis of the UK Supreme Court's For Women Scotland decision

Can trans women be defined as ‘women’ for the purposes of equality and non-discrimination law?
In a controversial judgment delivered on 16 April 2025 (For Women Scotland), the UK Supreme Court adopted what can be described as a predominantly biological interpretation of the terms “sex” and “woman” within the meaning of the British Equality Act, thereby excluding trans women from the legal category of women in Equality law[1]. This decision places the UK among the first countries in Europe whose highest court has taken a clear and definitive stance on the issue of the tension between ‘sex-based’ equality provisions and the new policies allowing for self-identification of gender identity. Indeed, both the right to equality and the right to personal autonomy regarding gender identity are recognized in the ECtHR and ECJ case law –but also, at the domestic level, in the Belgian Constitutional Court case law.

Starting from a critical analysis of the UK Supreme Court’s biological interpretation of the legal definition of “women” in light of recent ECtHR case law, this paper aims to examine how the equality rights that were identified by the Court as “sex-based” (i.e. specific policies related to pregnancy and maternity, gender-based violence against women, and affirmative action measures) could be reimagined within a framework grounded in gender self-determination.