UK Supreme Court Unanimously Rules Legal Definition of “Woman” in the Equality Act 2010 is Based on Biological Sex; For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16

On 16 April 2025, the UK Supreme Court reached a unanimous decision, in the case of For Women Scotland Ltd v The Scottish Ministers [2025] USCK 16, that the terms ”man”, “woman” and “sex” in the Equality Act 2010 (“EqA”) refer to a biological man, a biological woman and biological sex, and therefore that the legal definitions of “man” and “woman” do not include transgender men and transgender women. 

However, the Court also went on to warn that this judgment should not be taken as being a triumph of one or more groups in society over others, and reiterated that the EqA will continue to give transgender people protection from discrimination and harassment through the protected characteristic of gender reassignment, as it already does.

This judgment comes in the wake of a recent spate of high-profile cases (both decided and ongoing), dealing with the tension between gender critical and transgender rights in the workplace and public sphere.  These cases have, broadly speaking, established the principle that the holding and expression of gender critical beliefs are protected under the EqA (provided they are expressed appropriately), and that there is a balance to be struck between such beliefs and the rights of transgender people (who are also protected from discrimination and harassment under the EqA).  In addition, the recent case of Higgs v Farmor’s School [2025] EWCA Civ 109 established that any action taken by employers in relation to staff who express gender critical beliefs must be objectively justifiable in the circumstances, as a proportionate means of achieving a legitimate aim.  Similar principles apply in respect of single sex facilities and services.

The For Women Scotland case provides further clarification on the vexed question of how to balance these competing rights, and will no doubt provide helpful guidance for related cases in this arena which are yet to be decided.

We take a closer look at the findings in the For Women Scotland case below, and explore in more detail what this landmark judgment means for organisations.

What was the For Women Scotland case about?

The For Women Scotland case came about as the result of a 2018 initiative, by the Scottish government, to improve female representation on public boards.  That initiative gave rise to the Gender Representation on Public Boards (Scotland) Act 2018 (“GRPB Act”), which requires positive action to be taken to redress gender imbalances on public sector boards in Scotland. 

It also gave rise to associated statutory guidance (“Guidance”), which – together with the GRPB Act – effectively stated that transgender women with a Gender Recognition Certificate (“Certificate”) were to be legally classed as women, in accordance with the Gender Recognition Act 2004 and the EqA. 

This would have meant that transgender women with a Certificate would have been included in the figures for female representation on public boards; it would also have given such individuals the right to use female single sex services and spaces.

For Women Scotland (which campaigns for the strengthening of women’s and children’s rights in Scotland) appealed against the implementation of the Guidance, to the Court of Session; with Sex Matters, Scottish Lesbians, The Lesbian Project, LGB Alliance, the Equality and Human Rights Commission, and Amnesty International intervening.  For Women Scotland contended that the definition of “woman” in the EqA should be taken as a reference to a biological woman only. The Court of Session upheld the Guidance.  

For Women Scotland then appealed to the Supreme Court, which allowed its appeal.

What did the Supreme Court say? 

The Supreme Court held that the terms “man”, “woman” and “sex” in the EqA refer to biological sex only, and should not be interpreted to include “certificated” sex.  It commented that:

• Allowing certificated sex to be included in these definitions would lead to incoherence in the EqA; particularly in relation to areas like pregnancy, maternity and sex-based protections, which would become unworkable unless “man”, “woman” and “sex” were given a biological meaning.

• The Court rejected the suggestion that “woman” and “sex” could refer to biological sex in some sections of the EqA and certificated sex in others.  The meaning of those terms had to be consistent throughout.

• The Court noted that it is important that the EqA is interpreted in a clear and consistent way, in order for groups which share a protected characteristic to be identifiable by employers and service providers, who are subject to obligations under the EqA, and so that those obligations can be complied with in a practical way.

• Similarly, other legal provisions require a biological interpretation of “sex” in order to function coherently, such as those relating to separate spaces and single sex services (including changing rooms, hostels and medical services), communal accommodation, and single sex higher education institutions.  These provisions would also become unworkable with a certificated sex interpretation. 

• Similar confusion and impracticability would arise in the operation of provisions relating to single sex characteristic associations and charities, women’s fair participation in sport, the operation of the public sector equality duty, and the armed forces.    

The Court took into consideration that a certificated sex interpretation of the EqA had the potential to erode the protections given to others, such as those with the protected characteristic of sexual orientation.  For example, this could interfere with the ability of those in the lesbian community to have lesbian-only spaces and associations.

The Court also commented that giving greater rights to transgender people with Certificates, in comparison to transgender people without Certificates, by including the former in the legal definition of their acquired sex, had the potential to unfairly divide the transgender community and create practical issues for employers and service providers alike (who cannot lawfully ask if someone holds a Certificate). 

However, the Court also emphasised that its judgment does not deprive transgender people of legal protection.  Gender reassignment remains a protected characteristic under the EqA, and discrimination on this basis (including direct, indirect, harassment, by association and/or by perception) remains unlawful.  A certificated sex reading of the definitions in the EqA was not necessary to protect transgender people from unlawful discrimination.

What does this mean for organisations?

This landmark judgment clarifies that the legal interpretation of the concept of “sex” is a binary, biological one (specifically in the context of the EqA); whilst also being clear that those whose gender identity is different from the sex they were born with (i.e., those who are transgender) are protected from discrimination (also under the EqA).

The practical implications for employers and service providers alike are that:

• Gender critical beliefs (i.e. that sex is biological, immutable, binary and not to be conflated with gender) remain protected under the EqA, if expressed appropriately.  This principle was established in the Forstater v CGD Europe and Others UKEAT/0105/20/JOJ case, endorsed in the Higgs v Farmor’s School case, and has now effectively been further endorsed in the For Women Scotland case.

• Transgender people remain protected from all forms of discrimination and harassment under the EqA.  The For Women Scotland judgment is not to be seen as changing or undermining that in any way.

• The rights of those with gender critical beliefs and transgender people must be balanced in an appropriate and proportionate way; one should not automatically be favoured over the other.  The Courts in both For Women Scotland and Higgs v Farmor’s School were very clear on this point.  In the latter case, the Court stated that any interference with, or less favourable treatment in relation to, protected beliefs (including gender critical beliefs) will only be lawful where those beliefs have been inappropriately expressed or manifested and the action taken is objectively justifiable as a proportionate means of achieving a legitimate aim.  In the former case, the Court expressly said that its judgment was not to be taken to be a triumph of one or more groups in society over others, and reiterated that the EqA will continue to give transgender people protection from discrimination and harassment through the protected characteristic of gender reassignment, as it already does. 

• Having single sex facilities and services can be lawful, but must be objectively justifiable as a proportionate means of achieving a legitimate aim. A blanket prohibition on transgender people using the facilities or services of the gender with which they identify could amount to discriminatory treatment, unless it is objectively justifiable and proportionate.  Conversely, a policy which simply allows people to use the facilities and services of the gender they identify with, will be overly simplistic and may not be legally compliant.  It is crucial that the rights of both groups are balanced.  The best approach is for organisations to have an open, transparent dialogue with those affected by these issues, in a respectful way; hear what they each have to say about their viewpoints; carefully consider the feedback received and options available; and reach a reasonable and proportionate decision on the way forward.  Any such decision should also be kept under regular review, and may need to be adapted over time.

Futureproofing in this space will involve recognising that different groups will have different views (in some cases, deeply held), which may be valid and deserving of respect (even if not universally agreed with).  Encouraging an organisational culture where people can respectfully and constructively discuss these issues, and amicably agree to disagree if necessary, will be key.

The Equality and Human Rights Commission has stated that it will review and revise its guidance in this arena, in response to the For Women Scotland judgment.  We watch this space with interest.