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

This article was first published on the 16 April 2025, and has been updated following the publication of the EHRC Update.

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 some further clarification on the vexed question of how to balance these competing rights, and will likely provide contextual guidance for related cases in this arena which are yet to be decided.  However, the judgment (which was focussed on the limited and specific question of whether the terms “man”, “woman” and “sex” in the EqA should be given a biological meaning, in light of the provisions in the Gender Recognition Act 2004 regarding a person’s ability to change their legal sex for various purposes) arguably does not provide sufficient clarity around related issues arising in respect of single sex facilities and services, or provide any guidance on how to balance the rights of different groups when those rights may be in conflict with one another.

On 25 April 2025, the Equality and Human Rights Commission (“EHRC”) published “An Interim Update on the Practical Implications of the UK Supreme Court Judgment” (“EHRC Update”); highlighting (in brief) the main consequences of the For Women Scotland judgment for employers and service providers, including in relation to single sex facilities and services.  Unfortunately, the EHRC Update does not sufficiently clarify the position for employers and service providers.  It is hoped matters will become clearer when the EHRC publishes further statutory guidance in June 2025, following a period of consultation with relevant stakeholders from mid-May 2025.

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

What was the For Women Scotland case about?

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 the EHRC Update Say?

The EHRC Update provides a limited summary of the EHRC’s initial interpretation of a number of the key points in the Court’s judgment.  It states that:

• References to the word “sex” in the EqA mean biological sex.  This means that, under the EqA:

• A “woman” is a biological woman (a person born female).

• A “man” is a biological man (a person born male).

• If somebody identifies as transgender, they do not change sex for the purposes of the EqA, even if they have a Certificate.

• In workplaces, it is compulsory to provide sufficient single sex toilets, as well as sufficient single sex changing and washing facilities where these facilities are needed. 

• It is not compulsory for services that are open to the public to be provided on a single sex basis or to have single sex facilities such as toilets.  These can be single sex if that is objectively justifiable as a proportionate means of achieving a legitimate aim (and other conditions in the EqA are met).  However, it could be indirect sex discrimination if the only provision is mixed sex. 

• In workplaces and services that are open to the public:

• Transgender women should not be permitted to use the women’s facilities and transgender men should not be permitted to use the men’s facilities, as this will mean that they are no longer single sex facilities and must be open to all users of the opposite sex.

• In some circumstances, the law also allows transgender women not to be permitted to use the men’s facilities, and transgender women not to be permitted to use the women’s facilities.

• However, where facilities are available to both men and women, transgender people should not be put in a position where there are no facilities for them to use.

• Where possible, mixed sex toilet, washing or changing facilities in addition to single sex facilities should be provided.

• Where toilet, washing or changing facilities are in lockable rooms (not cubicles) which are intended for the use of one person at a time, they can be used by either women or men.

Though the EHRC Update does not expressly say so, the Court made clear in its judgment that transgender people are protected from direct and indirect discrimination and harassment under the EqA, and that this protection has not been changed or undermined by its findings.  This should be borne in mind in relation to the limited interim guidance outlined above. 

It is also important to bear in mind that the EHRC Update is interim guidance only, and does not change the law in any way.  Nor does it provide any practical guidance for organisations on balancing the rights of those with different protected characteristics where those rights compete or conflict.   

Some of these limitations were highlighted by the Government in a recent House of Lords debate on the EHRC Update (in the course of which it was also noted that the Government was not, surprisingly, informed or consulted about the EHRC Update in advance of publication).  Perhaps, owing to these limitations, the Government appeared anxious to play down the legal significance of the EHRC Update, describing it as “a perspective” on the Court’s judgment rather than anything more binding or persuasive.

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 does not change or undermine this protection.  Consideration should be given to whether transgender staff may need extra support in the wake of the judgment (which has caused upset and anxiety in the transgender community).

• 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. Consideration must also be given to the fact that transgender people are protected from discrimination and harassment under the EqA, and entitled to appropriate facilities.  The EHRC Update states that transgender people should not be allowed to use the facilities of the sex with which they identify, but it also makes clear that transgender people should not be put in a position where there are no facilities for them to use. This appears to suggest that where possible, mixed sex facilities should be provided in addition to single sex facilities. 
  
• The EHRC Update does not provide sufficient clarity or practical guidance for organisations, and fuller statutory guidance is eagerly awaited.  Given that that biological men and women and transgender people are all protected from direct and indirect discrimination and harassment under the EqA (subject to certain exemptions for single sex  services and spaces), and in the absence of updated statutory guidance on this issue, organisations should give very careful consideration to whether it is appropriate to take action, and/or change policies and procedures, now, while we await the statutory guidance, or whether it would be more prudent to wait for the publication of that guidance.
  Importantly, the EHRC Update does not address the very sensitive and complex question of how to balance (a) the provision of single sex facilities for men and women, and the right of men and women not to be discriminated against or harassed because of their sex, against (b) the right of transgender people not to be discriminated against or harassed because of their gender reassignment.  This leaves organisations in a difficult position: understanding how to balance these competing rights will be crucial in avoiding discrimination claims being brought.
  The limited guidance set out in the EHRC Update also gives rise to a number of practical difficulties for organisations. 
  For example, though the EHRC Update states that transgender people should not be allowed to use the facilities of the sex with which they identify, in practice, organisations may not be able to identify which individuals are transgender, and cannot simply ask. They may therefore have no way of knowing which facilities individuals should be using.  Secondly, requiring a transgender person to use the facilities of their biological sex, rather than those of the sex with which they identify (and likely present as), may have the unintended consequence of “outing” that person as transgender; which could be discriminatory, and may infringe other legal rights.
  In some instances, it would also be discriminatory if appropriate facilities and services were not provided for transgender people.   The EHRC Update confirms that transgender people should not be put in a position where there are no facilities for them to use, but gives little guidance on how to ensure this or what appropriate facilities might look like in practice.
  However, simply allowing transgender people to continue to use the facilities of the sex with which they identify would also be problematic and give rise to legal risk for organisations, in light of the For Women Scotland judgment.
  The EHRC Update suggests that the provision of mixed sex facilities, in addition to single-sex facilities, might address the issue; but for many organisations, implementing this potential solution is unlikely to be practicable in the short term. It is not clear how this might be addressed in the meantime, or in circumstances where mixed-sex facilities are not a practicable option at all. 
  In relation to workplaces specifically, though applicable health and safety legislation does say that mixed sex toilets are permitted if each toilet is in a separate room (rather than a cubicle) which is lockable from the inside, it also says that, if toilets are not in separate lockable rooms, there must be separate provision for men and women. No guidance or explanation is given regarding transgender employees.  Employers may need to review their existing facilities and policies, in light of the For Women Scotland judgment, and consider how best to provide mixed sex facilities in addition to any single sex facilities.
  
• Any policies, procedures and staff training, to which the decision in For Women Scotland may be relevant, should be reviewed and updated at the appropriate time.  This may include carrying out a risk assessment to evaluate whether any aspects of the organisation may be impacted, and assessing any associated risks which are identified. Any proposed actions should be proportionate.  Data collection and equality monitoring may also need to be considered.  However, organisations will need to reflect carefully on, and/or carry out a risked based assessment in relation to, when the optimal time to review and update policies, procedures and staff training will be; in light of the fact that the statutory EHRC guidance remains pending.

Many difficult questions remain answered. Futureproofing in this area will involve recognising that different groups will have different and sometimes deeply held views which may be equally valid and deserving of respect.  Encouraging an organisational culture where people can respectfully and constructively discuss these issues, and amicably agree to disagree if necessary (subject to compliance with legal obligations), will be key.

The EHRC has stated that it will review and revise its guidance in response to the For Women Scotland judgment. The Government, for its part, has reminded the EHRC of the need to consult widely and broadly among those affected, listening to diverse voices, before preparing its draft updated guidance.  That consultation, and the guidance which will follow, are both eagerly awaited.

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The material in this article is provided for guidance and general information only and is not intended to constitute legal or other professional advice upon which you should rely. In particular, the information should not be used as a substitute for a full and proper consultation with a suitably qualified professional. Please do contact the Bates Wells team if you require further information.