Defining “Woman” in Law: Biological Interpretation after For Women Scotland [2025]

By Sabina Jones

The distinction between sex and gender has emerged as a contemporary issue within UK law, evolving through attempts to balance the biological understanding of sex with recognition of legal gender identity. The For Women Scotland judgments clarify the statutory definition of a woman under the Equality Act 2010 (EA 2010), with the most recent ruling creating significant implications for the protection and recognition of transgender rights.

Context

For Women Scotland

For Women Scotland (FWS) is a campaign group established in 2018 that opposes the inclusion of trans women within the legal definition of a ‘woman’ under the EA 2010. The group’s core principles focus on protecting ‘sex’ in policy, supporting those who voice their opinions on gender-related policy issues and promoting evidence-based discussion if it aligns with their gender-critical stance. [1] In 2023, the Court of Appeal decided that ‘woman’ could include Gender Recognition Certificate (GRC) holders under the EA 2010. In 2024, FWS were granted permission to appeal this in the Supreme Court, challenging the exact interpretation of ‘women’ under the Gender Representation on Public Boards (Scotland) Act 2018 (ASP 2018). [2]

They received extensive funding from author JK Rowling. [3] Amery argues that ‘gender-critical’ organisations such as FWS believe that the legal recognition trans people’s gender would ‘fatally undermines the governance of gender difference’. [4] Whilst the organisation can be perceived as ‘gender-critical’, it may be regarded as necessary for preserving feminist structures.

FWS comment that: “We believe there are only two sexes, that a person’s sex is not a choice, nor can it be changed. Women are entitled to dignity, safety and fairness”, places FWS in a highly polarising position within debates on sex and gender in the UK. [5] This statement demonstrates a strict and almost dogmatic biological interpretation of sex, excluding the modern recognition of gender identity. The application of such a rigid approach risks ‘biological essentialism’, contradicting more inclusive perspectives adopted by institutions such as TransActual. [6]

Legal framework

There are three key legal frameworks scrutinised in the FWS judgments. These include EA 2010, created to protect people from discrimination, by defines sex as ‘a person who has a particular protected characteristic is a reference to a man or to a woman’. [7] The Gender Recognition Act 2004 (GRA 2004) which permits transgender individuals to legally change their gender identity through a GRC. [8] Subsequently, ASP 2018, aiming to achieve a gender balance of 50% female representation on public boards. [9] The guidance issued included trans women in possession of a GRC. [10] The interaction of these statutes in the FWS judgments demonstrates how the litigation has evoked questions about the interpretation of UK equality law where different legislative definitions of gender intersect.

The landmark Supreme Court case concerned whether the definition of a ‘woman’ under the EA 2010 referred to biological sex only or whether it included those with a female Gender Recognition Certificate (GRC). [11] This appeal followed the Court of Appeal decision where Scottish Ministers provided guidance that the EA 2010’s definition included those with a female GRC. FWS sought judicial review claiming this was beyond the legislative competence of the Scottish Government and inconsistent with the EA 2010. [12] The Supreme Court allowed the appeal, ultimately ruling that the guidance was incorrect. They clarified that under EA 2010; the definition of a ‘woman’ refers to biological sex and excludes trans women. [13]

This ruling is significant because it represents a shift towards a restrictive interpretation of equality legislation. Chaiyajit claims that gender recognition has now been ‘reframed’ as ‘containment’, suggesting that trans women can be recognised on paper but not democratically. [14] This suggests that, despite trans women being recognised legally through GRCs, it does not equate to full participation within society. Arguably they are ‘contain[ed]’ into narrow definitions, inconsistent with modern standards of inclusion. This highlights the need for more meaningful democratic recognition, ensuring that trans women are not only recognised at law but treated equally within society.

The Supreme Court demonstrates a literal reading in their judgment, departing from previous inclusivity, introducing an approach inconsistent with developing social understandings of gender. This approach could be seen as regressive, backtracking on previous broader interpretations of equality legislation and arguably not following previous precedent. However, it could be argued that the Supreme Court was simply applying Parliament’s wording rather than intentionally restricting trans rights, particularly as trans individuals remain protected under the Section 7 EA 2010 characteristic of gender reassignment. The FWS appeal has progressed through three stages, each examining the interaction between ASP 2018, GRA 2004 and EA 2010.

Inner House

Section 2 of ASP 2018 defined women broadly to include transgender women, those undergoing gender reassignment and ‘those living as women’. [15] FWS challenged this definition, claiming it overstepped the legislative competence of the Scottish government and concerned the reserved matter of ‘equal opportunities’ under Schedule 5 of the Scotland Act 1998.

The EA 2010 defines a ‘woman’ as ‘a female of any age’. The Court of Session’s Inner House held that the Scottish government did have the power to alter the EA 2010’s definition of a ‘woman’ as this was a reserved matter. The court held that the EA definition excluded those ‘living’ as women. The Scottish Ministers issued revised statutory guidance, stating that the term ‘woman’ should be read as per the EA 2010, however, they also stated that any person with a female GRC was to be treated as a woman. [16][17]

Court of Appeal

The revised guidance accommodated the EA 2010 but included those with a female GRC certificate, creating movement toward a more inclusive approach. FWS challenged this guidance, maintaining that it should refer to biological females only.  The appeal was dismissed by both the Inner and Outer house of the Court of Session, clarifying that the EA’s definition of a ‘woman’ could accommodate female GRC holders. Therefore, applying a purposive approach and aligning with equality principles. [18]

Supreme Court

In 2025, the Supreme Court ruled in favour of FWS clarifying that, for the purposes of the ASP 2018, the use of ‘sex’ and the terms ‘man’ and ‘woman’ in the EA only refer to biological sex. [19] This was a monumental shift in the law, making changes in an area many believed was already clear under the EA, rather than clarifying the position, it has produced further uncertainty. The judgment has amplified the division between advocacy groups such as FWS and TransActual. [20]

Significance of the ruling

The controversial 2025 ruling is a milestone judgment in the ongoing debate over trans-inclusion. Scottish Trans leader Vic Valentine suggests that the judgment lacked trans voices, increasing the fear that by excluding transgender people in policymaking, this risks the erosion of trans inclusion. The ruling has significant implications for trans rights by excluding their recognition as women and reducing the importance of a GRC.  The denial of trans experiences through this case could be perceived as a step backwards in the development of trans-inclusion. [21]

Former First Minister of Scotland, Nicola Sturgeon commented that we are risking making trans lives ‘almost unliveable’. [22] This sparks potential for further disputes, inspiring backlash on social media and strengthening tension between activist groups. This arguably exacerbates marginalisation of trans voices. Many took to social media after the UKSC ruling stating that it was ‘transphobic’ and claiming it was an attack on their rights. [23] As a result, protests took place all over the UK, including in Cardiff city centre with over a thousand attendees. [24] The increasing divide between feminist and trans activist groups, demonstrates the detrimental impact of this ruling.

Supporters of FWS argue that this ruling provided ‘much- needed clarity’ as it determined the legal definition of a ‘woman’ in line with the EA, clarifying the debate on whether a GRC can change a person’s legal sex for the purpose of the EA. [25] The ruling did not allow the redefining of protected characteristics by devolved legislatures, receiving criticism that the law does not align with the developing flexible gender definitions within society.  However, it does ensure the consistent application by public bodies of the EA 2010, reducing inconsistent decision making in the creation of women-only spaces such as bathrooms and changing facilities. [26] Critics such as Gascoigne recognise that competing interests ‘remain contextual’ and ‘complex’ however put forward that this ruling is ‘contentious’ despite the clarity provided. [27] This is evident through widespread outrage on social media platforms such as X.

On the other hand, legal critic Wigley claims the court’s decision did not address a ‘number of highly significant issues’, suggesting that the ruling was insufficiently considered. [28] This omission sparks concern that future cases may produce inconsistent interpretations of how the EA 2010 and GRA 2004 interact due to gaps in the judgment. Section 7 EA 2010 raises concerns on human rights implications and the lack of framework for public bodies such as hospitals and schools, increasing uncertainty on how trans rights will be protected in future cases. Wigley’s criticism highlights the courts failure to engage with the human rights aspect of the decision. Under the European Convention on Human Rights Article 8 protects the right for private life. [29] By excluding trans women from the definition of a ‘woman’ this can be seen to interfere with this right, going against the convention. Further, it could be argued that the judgement interferes with article 14, regarding prohibition of discrimination. The separation of trans women from cisgender women can amount to a discrimination based on gender identity, a protected characteristic. By failing to address these ‘highly significant issues’ the court risks non-compliance with the ECHR.

Alternatively, Bradley argues that the court ‘misapplied (…) the correct interpretative approach’. [30] Adopting a rigid and fixed definition of ‘sex’ demonstrates a departure from modern day society and the increasing popularity of gender fluidity, arguably makes it inconsistent with modern cases. Bradley’s criticism highlights that the court failed to interpret the EA 2010 in accordance with the aim to prevent discrimination. Whilst the ruling aimed to provide clarity, it has arguably created ambiguity in protection of trans rights under EA 2010, meaning future judgments will need to confirm how the framework is applied. As suggested by Bradley, failing to address how trans women will be protected under equality law, has created uncertainty for trans women’s future. 

Suggesting a different approach to the case would have been more beneficial for the courts. By focusing on biological sex protections risks courts misapplying the framework in everyday cases, arguably undermining the purpose of this ruling, leaving policymakers in a more difficult position.

Overall, the For Women Scotland judgments demonstrates growing tensions in UK equality law regarding biological sex and social gender identity. The 2025 ruling, whilst clarifying the legal definition, highlights the limitations of a fixed framework, arguably inapplicable to modern gender diversity. By prioritising legal definitions over inclusivity, the Supreme Court has sparked nationwide debates about the compatibility of the ruling with the ECHR. To engage with the social realities of gender identity in the modern UK, reform will be necessary.

References:

1. For Women Scotland: Home (For Women Scotland) https://forwomen.scot accessed March 29, 2026.

2. For Women Scotland Ltd v Scottish Ministers [2023] CSIH 37.

3. Baska 'JK Rowling reportedly donates £70,000 to group’s Supreme Court appeal over ‘woman’ definition' (PinkNews, February 19) https://www.thepinknews.com/2024/02/19/jk-rowling-for-women-scotland-donation-legal-definition-woman/ accessed March 29, 2026.

4. Fran Amery, ‘ Gender Critical’ feminism as a biopolitical project’ (May 2024) https://journals.sagepub.com/doi/full/10.1177/13634607241257397.

5. For Women Scotland: Home (For Women Scotland) https://forwomen.scot accessed March 29, 2026.

6. Alison Phipps and Rachel Aslop. ‘Transgender equality and the UK Supreme Court: a transgender studies community roundtable.’ (2025) https://www.tandfonline.com/doi/citedby/10.1080/09589236.2025.2549206?scroll=top&needAccess=true.

7. The Equality Act 2010, section 11(a).

8. The Gender Recognition Act 2004, section 1.

9. The Gender Representation on Public Boards (Scotland) Act 2018, section 1.

10. The Gender Representation on Public Boards (Scotland) Act 2018, section 1.

11. For Women Scotland v The Scottish Ministers [2025] UKSC 16.

12. For Women Scotland v The Scottish Ministers [2023] CSIH 37, paragraph 5.

13. For Women Scotland v The Scottish Ministers [2025] UKSC 16, paragraph 266.

14. Nada Chaiyajit, ‘Partocratic Democracy: When Gender Equality Is Conditioned Upon Masculine and Cis-Heteronormative Conformity – Lessons from the UK Supreme Court (2025) and Thailand’s Constitutional Court (Decision No. 20/2564) https://so08.tci-thaijo.org/index.php/MFULJ/article/view/5405 accessed January 20, 2026.

15. Gender Representation on Public Boards (Scotland) Act 2018, section 2 (repealed).

16. Scottish Government, Gender Representation on Public Boards (Scotland) Act 2018: Statutory Guidance (2022).

17. For Women Scotland v The Scottish Ministers [2022] CSIH 4.

18. For Women Scotland v The Scottish Ministers [2023] CSIH 39.

19. For Women Scotland v The Scottish Ministers [2025] UKSC 16, paragraph 266.

20. For Women Scotland v The Scottish Ministers [2025] UKSC 16.

21. Clare Dyer, ‘UK ruling that woman refers to biological sex “brings clarity”, says government (2025) https://www.proquest.com/openview/84c98e85b72fb8ae6fc7649a969096d0/1?pq-origsite=gscholar&cbl=2043523.

22. ‘Trans life could become ‘unliveable’ - Sturgeon’. BBC News, https://www.bbc.co.uk/news/articles/cvgn2gyx9vdo accessed March 29, 2026.

23. ‘Life for our community is a living hell after court ruling.’ (BBC News, May 2025) https://www.bbc.co.uk/news/articles/c1e6l89wyewo accessed March 29 2026.

24. ‘Protest over Supreme Court gender ruling’. BBC News, April 2025. https://www.bbc.co.uk/news/articles/cwyn80edzp5o accessed March 2026.

25. Rosie Walker, ‘ Supreme Court decision provides much-needed clarity over the definition of sex for the Equality Act 2010’( April 2025)  https://gilsongray.co.uk/insights/supreme-court-clarifies-definition-of-sex-under-equality-act-2010-gilson-gray/#:~:text=The%20Supreme%20Court%20held%20that,GRC)%20in%20their%20acquired%20gender. accessed March 2026.

26. Clare Dyer, ‘UK ruling that woman refers to biological sex “brings clarity”, says government (2025) https://www.proquest.com/openview/84c98e85b72fb8ae6fc7649a969096d0/1?pq-origsite=gscholar&cbl=2043523.

27. Mollie Gascoigne, ‘Sex, statutory Interpretation and the Supreme Court: A comment on For women Scotland v Scottish Ministers for Employment Law and Practice (2025) https://academic.oup.com/ilj/article/54/3/693/8196513?login=true accessed October 2025.

28. Crash Wigley, ‘For Women Scotland: a legal critique’ (2025) https://goodlawproject.org/for-women-scotland-a-legal-critique/ accessed October 2025.

29. European Convention on Human Rights 1953, Article 8.

30. Claire Bradley, ‘A detailed legal analysis which explains why the case of For Women Scotland was wrongly decided by the UK Supreme Court’ https://www.europeanlawmonitor.org/academic-articles/4584-a-detailed-legal-analysis-of-why-the-case-of-for-women-scotland-was-wrongly-decided-by-the-uk-supreme-court accessed October 2025.