Clarifying Equality: The History of the Equality Act 2010, the Supreme Court Ruling on the Definition of “Woman”, and What It Means for Employers Today
Introduction: A Turning Point in UK Equality Law
On 16 April 2025, the UK Supreme Court delivered a landmark ruling in For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16 that will shape the future of workplace policy, data handling, and service provision across the UK. In its judgment, the Court confirmed that the term “woman” in the Equality Act 2010 refers exclusively to biological females when single-sex exceptions apply. This means that transgender women, even those with a Gender Recognition Certificate (GRC), are not included within that definition for the purposes of sex-based legal provisions.
While the protected characteristic of gender reassignment remains untouched and fully valid, this decision fundamentally reorients how sex-based rights and legal obligations are interpreted, especially in areas involving privacy, dignity, and safeguarding.
But to fully grasp the implications of this decision, we must look back at how the Equality Act came to be, its purpose, its gaps, and the legal tensions it has struggled to reconcile over the last 15 years.
The Origins and Intent of the Equality Act 2010
Why Was the Equality Act Created?
The Equality Act 2010 was introduced to streamline and consolidate more than 100 pieces of prior anti-discrimination legislation. Prior to 2010, employers and service providers had to navigate a patchwork of separate laws, each covering different forms of discrimination, with inconsistent definitions and standards.
Key acts it replaced include:
The Sex Discrimination Act 1975
The Race Relations Act 1976
The Disability Discrimination Act 1995
The Equal Pay Act 1970
The Employment Equality (Sexual Orientation) Regulations 2003
The Employment Equality (Religion or Belief) Regulations 2003
The Employment Equality (Age) Regulations 2006
The Equality Act aimed to simplify compliance, clarify obligations, and make equality law more accessible for employees and organisations alike. It was designed with the idea that fairness should be consistent across all protected characteristics, but this simplicity also introduced complications when rights came into conflict.
The Nine Protected Characteristics
Under the Act, individuals are protected from discrimination on the basis of:
Age
Disability
Gender reassignment
Marriage and civil partnership
Pregnancy and maternity
Race
Religion or belief
Sex
Sexual orientation
While each characteristic has its own legal nuances, the most contentious, and arguably most legally complex, have been sex and gender reassignment.
Sex vs Gender Reassignment: The Tension at the Heart of the Act
The Equality Act does two things that set the stage for conflict:
It provides strong protection for individuals undergoing or proposing to undergo gender reassignment (including trans women and non-binary individuals).
It also allows for exceptions to these protections in the form of single-sex provisions, such as women-only services, spaces, and roles.
However, nowhere in the Act are the terms “man” or “woman” defined. It does not clarify whether these are:
Based on biological sex (assigned at birth),
Legal sex (as recorded on a birth certificate or Gender Recognition Certificate),
Or gender identity (how someone lives and presents themselves).
This lack of definition has been the source of increasing legal uncertainty.
Key Legal Cases Leading to the 2025 Supreme Court Decision
Several important cases tested the Equality Act’s boundaries. Here are some of the most pivotal:
1. A v Chief Constable of West Yorkshire Police [2014]
Held that trans individuals are protected under the Equality Act even if they haven’t undergone full transition or obtained a GRC.
Signalled broad interpretation of gender reassignment.
2. Taylor v Jaguar Land Rover Ltd [2020]
The employment tribunal ruled that non-binary and gender-fluid identities fall under the protection of gender reassignment.
A landmark for workplace inclusion, though appealed and later settled.
3. Forstater v CGD Europe [2021]
Maya Forstater’s belief that sex is binary and immutable was ruled as a protected philosophical belief under the Equality Act.
Reasserted that holding gender-critical views is lawful, even if controversial.
These cases showed how the Act could be used both to protect gender identity and to defend beliefs based on biological sex. But they also revealed the challenge: what happens when the rights of one protected group are seen to conflict with another?
The 2025 Supreme Court Ruling: A Defining Moment
The Background
The case For Women Scotland Ltd v The Scottish Ministers involved a challenge to Scottish Government regulations made under the Gender Representation on Public Boards (Scotland) Act 2018.
This Act aimed to improve the representation of women on public boards in Scotland. The controversy arose because the Scottish Government’s statutory guidance and secondary legislation redefined “woman” to include transgender women who hold a Gender Recognition Certificate (GRC).
Summary Timeline
2018
Legislation introduced
GRPB (Scotland) Act passed
2021
Outer House (Court of Session)
Ruled in favour of Scottish Government
2022
Inner House (Court of Session)
Ruled in favour of For Women Scotland
2023
Revised regulations and second challenge
Mixed rulings, escalated again
2024
Case heard by UK Supreme Court
Final appeal granted
2025
Supreme Court ruling
Ruled in favour of For Women Scotland
The Judgment
The Supreme Court ruled that:
“The protected characteristic of sex refers to biological sex. Parliament intended to preserve the integrity of single-sex exceptions. The concept of sex in this context does not include individuals who are biologically male, regardless of legal recognition through a GRC.”
What Changed?
The term “woman” in single-sex contexts must now be interpreted to mean biological female.
A GRC does not change this for the purpose of the Equality Act’s exceptions.
This ruling affects how employers and service providers can lawfully differentiate based on sex.
Practical Implications for Employers and Service Providers
This ruling is not a licence for blanket exclusion or discrimination. But it does mean that, where single-sex exceptions are permitted, the legal test now requires a biological sex basis, not gender identity or legal sex.
1. Recruitment
Employers may lawfully restrict some roles to biological women, particularly where:
Safeguarding is involved (e.g. women’s refuges, schools, healthcare)
There is a need for privacy (e.g. changing areas, intimate care)
The exception is a proportionate means of achieving a legitimate aim
2. Single-Sex Services
Women-only spaces (such as domestic abuse shelters or hospital wards) can lawfully exclude trans women if the justification is clear, proportionate, and based on need.
3. Gender Pay Gap Reporting
Employers must ensure gender pay gap and equal pay analysis is based on biological sex, not self-declared gender identity or GRC status.
4. Workplace Policies
Equality and D&I policies must be reviewed to:
Ensure clarity around definitions of sex and gender
Reflect the legal distinction between sex-based and gender reassignment-based rights
Avoid unlawful discrimination in either direction
5. Staff Communication and Culture
Navigating this ruling will require careful communication, particularly in inclusive workplaces where trans employees and allies may feel vulnerable or confused by the implications.
Key Questions for HR Leaders and Line Managers to Consider:
Have we reviewed our equality, safeguarding, and recruitment policies in light of this ruling?
How do we currently define “sex” and “gender” in our HRIS and employee data records?
Are we confident that any single-sex requirements are justified and documented appropriately?
Do line managers understand the difference between legal protections for sex and gender reassignment?
Are we prepared to support staff through a period of policy change, legal clarity, and possible internal tensions?
Ethical and Cultural Considerations:
Legal compliance is only one part of the equation. This ruling arrives in a politically and socially sensitive environment. Employers will need to:
Tread carefully between protecting sex-based rights and ensuring continued dignity and inclusion for trans colleagues
Avoid over-correction or underreaction
Recognise the emotional and personal toll these issues can have on staff across the spectrum
Compassion, clarity, and confidence will be the three most important leadership traits in the months ahead.
Where Might the Law Go Next?
The ruling may prompt:
Government guidance or further legislation to clarify employer responsibilities
New challenges to existing policies or services
Calls for amendment of the Equality Act to reflect modern understandings of sex and gender
Further cases testing the limits of this judgment in education, healthcare, and prisons
The Supreme Court’s judgment is now the definitive legal interpretation of the Equality Act 2010 in this context. Employers and service providers must respond accordingly, as only Parliament can amend or override this ruling through new legislation.
Conclusion: A New Chapter in Equality Law
The Equality Act 2010 was designed to harmonise, not polarise. But the evolving legal and cultural debate over the meaning of sex and gender shows that true equality law is rarely simple.
The 2025 Supreme Court ruling gives legal clarity on one point, but leaves a wider challenge: how do we uphold sex-based rights while fostering inclusive, respectful, and lawful workplaces for everyone?
The answer lies in doing the work: reviewing policies, listening to your people, seeking expert guidance, and leading with integrity.
Need Help Navigating These Changes?
At Thrive., we help forward-thinking leaders and people professionals translate complex legal changes into practical, inclusive, and legally sound action. Whether you’re reviewing recruitment policies, updating gender pay reporting, or training line managers, we’re here to support you.
Let’s start a conversation that puts people first, while staying fully compliant.
References & Further Reading
Equality Act 2010
UK Parliament legislation consolidating and updating discrimination law across nine protected characteristics.
https://www.legislation.gov.uk/ukpga/2010/15/contentsGender Representation on Public Boards (Scotland) Act 2018
Scottish Parliament legislation aimed at improving the representation of women on public boards.
https://www.legislation.gov.uk/asp/2018/4/contents/enactedFor Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16
UK Supreme Court decision confirming that the term “woman” in the Equality Act refers to biological sex where single-sex exceptions apply.
https://www.supremecourt.uk/cases/uksc-2023-0099.html (Placeholder — link will be live when judgment is published)For Women Scotland Ltd v The Scottish Ministers [2022] CSIH 4
Inner House of the Court of Session decision overturning earlier ruling and holding that the Scottish Government’s definition of “woman” was unlawful.
https://www.scotcourts.gov.uk/docs/default-source/cos-general-docs/pdf-docs-for-opinions/2022csi004.pdfForstater v CGD Europe & Others [2021] UKEAT/0105/20/JOJ
Employment Appeal Tribunal ruling that gender-critical beliefs are protected under the Equality Act as a philosophical belief.
https://www.gov.uk/employment-appeal-tribunal-decisions/maya-forstater-v-cgd-europe-and-others-ukeat-slash-0105-slash-20-slash-jojTaylor v Jaguar Land Rover Ltd [2020] ET/1304471/2018
Employment Tribunal ruling that extended gender reassignment protections to non-binary and gender-fluid people.
https://www.gov.uk/employment-tribunal-decisions/mr-r-taylor-v-jaguar-land-rover-ltd-1304471-2018A v Chief Constable of West Yorkshire Police [2014] EWCA Civ 1367
Court of Appeal case affirming the broad scope of protection for transgender individuals under gender reassignment provisions.
https://www.bailii.org/ew/cases/EWCA/Civ/2014/1367.htmlScotland Act 1998
UK legislation establishing the devolved powers of the Scottish Parliament, including the reservation of equal opportunities law.
https://www.legislation.gov.uk/ukpga/1998/46/contents
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