Supreme Court rules the Equality Act definition of a woman is based on biological sex

In a landmark decision, the Supreme Court has ruled that the term “woman” in the Equality Act 2010, means a biological woman (someone who was female at birth) and “sex” means biological sex. We look at why the Supreme Court reached the decision it did and what it means for employers.

What was the case about?

The debate on this issue began after the Scottish Parliament passed a law in 2018 to establish gender quotas for public sector boards, which were aimed at increasing the number of women sitting on them.

“Woman” is defined as including a person who has the protected characteristic of gender reassignment within the meaning the Equality Act 2010 (Equality Act). 

For Women Scotland Ltd (FWS), an organisation that campaigns to strengthen the rights of women and children in Scotland, raised issue with the fact that ministers had included transgender women as counting as women.

They brought a judicial review against the Scottish ministers over their definition of “woman” in the legislation and the related statutory guidance. FWS won their judicial review on appeal.

In response, the Scottish ministers issued revised statutory guidance in 2022. The revised guidance said that “woman” meant a woman as defined by the Equality Act and included trans women who have a full gender recognition certificate under the Gender Recognition Act 2004. 

Under the 2004 Act a trans person who is at least 18 years old can apply for legal recognition of their "acquired gender" through the issue of a gender recognition certificate. The 2004 Act says, “where a full gender recognition certificate has been issued to a person that their acquired gender is female, the person’s sex is that of a woman.”

FWS brought a further judicial review to challenge the revised statutory guidance issued by the Scottish ministers. They alleged that including trans women in the definition of "woman" was not correct and went beyond the legislative competence of the Scottish Parliament. 

Both the Outer House and the Inner House of the Court of Session ruled that the revised statutory guidance was not unlawful, concluding that the definition of sex was not limited to biological or birth sex. FWS appealed to the Supreme Court.

Sex Matters (whose chief executive is Maya Forstater), the Equality and Human Rights Commission (EHRC), Amnesty International, Scottish Lesbians, The Lesbian Project and LGB Alliance intervened.

What did the Supreme Court decide?

The central question the UK’s highest court had to decide in this case was whether the term “woman” in the Equality Act 2010, means a biological woman or whether it has a broader meaning to include people who have a gender recognition certificate.

FWS’ case was that “in the Equality Act, sex just means sex, as the word and the words women and man are understood and used in ordinary, everyday language, used every day in everyday situations by ordinary people.” The Scottish ministers’ case was that the term “woman” includes a person issued with a full gender recognition certificate in the acquired gender of female and excludes a person issued with a full gender recognition certificate in the acquired gender of male.

The unanimous ruling of the Supreme Court was that the term “woman” in the Equality Act 2010, means a biological woman, “man” means a biological man and “sex” means biological sex. Any other interpretation would render the Equality Act incoherent and impracticable to operate.

As a result, the Supreme Court decided that the guidance issued by the Scottish ministers was incorrect. A person with a gender recognition certificate in the female gender does not come within the definition of “woman” in the Equality Act or the legislation which sets quotas for public sector boards. This means they do not count towards achieving the goal set in the gender representation objective for public sector boards.

In reaching its decision, the Supreme Court was keen to stress that the ruling should not be seen as a triumph of one or more groups in our society at the expense of another. They emphasised that the law still protects transgender people from unlawful discrimination through the protected characteristic of gender reassignment, and against direct discrimination, indirect discrimination and harassment in their acquired gender.

Why did the Supreme Court reach the decision it did?

The Supreme Court highlighted the importance of the Equality Act being interpreted in a clear and consistent way so that groups which share a protected characteristic can be identified by those the Act imposes obligations on, and so they can comply with their obligations in practice.

They considered that interpreting “sex” as certificated sex would cut across the definitions of “man” and “woman” and the protected characteristic of sex in an incoherent way.

The Supreme Court noted that as a matter of ordinary language, the provisions relating to sex discrimination, and especially those relating to pregnancy and maternity, and to protection from risks specifically affecting women, can only be interpreted as referring to biological sex.

They rejected the idea that the words could have a different meaning in different places. For example, so that in the provisions relating to pregnancy and maternity in the Equality Act, sex would mean biological sex, while elsewhere sex would mean certificated sex.

The Supreme Court was concerned that if it agreed that sex included certificated sex, that would create two sub-groups within those who share the protected characteristic of gender reassignment, giving trans people who have a gender recognition certificate greater rights than those who do not. The majority of trans people do not have a gender reassignment certificate. 

They were also concerned that those seeking to comply with their obligations under the Act would have no obvious means of distinguishing between the two sub-groups to whom different duties were owed, particularly as they could not ask people whether they had obtained a certificate.

The Supreme Court considered that the certificated sex interpretation would also seriously weaken the protections given to those with the protected characteristic of sexual orientation. For example, by interfering with their ability to have lesbian-only spaces and associations.

There are other provisions whose proper functioning requires a biological interpretation of “sex”, according to the Supreme Court. These include the provisions on separate spaces and single-sex services (including changing rooms, hostels and medical services) and communal accommodation, amongst others.

Similar incoherence and impracticability were said to arise in terms of the 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.

In reaching its decision, the Supreme Court also looked at the history of sex discrimination legislation predating the Equality Act, including in the Sex Discrimination Act 1975 and found that when Parliament used the words “man” and “woman” originally, they referred to biological sex. When the Equality Act replaced the previous legislation, there was no indication that it changed in any material way the meaning of “man” and “woman” or “sex” from their original meanings. 

What does this mean for employers?

The decision means that trans people, whether or not they have a full gender recognition certificate, do not come under the definition of women for the purposes of the Equality Act. 

They continue to be protected, however, from direct and indirect discrimination and harassment under the protected characteristic of gender reassignment. Trans people also continue to be protected where they are discriminated against or harassed because of their perceived sex rather than because they are trans. 

They also continue to have privacy rights in relation to their previous gender, which is classed as special category data under UK data protection legislation. 

Britain’s equality regulator the EHRC says it welcomes the clarity this ruling brings and is “working at pace” to update its guidance in response to the judgment. Employers and other organisations will keenly await that guidance. 

In the meantime, the UK Prime Minister, Kier Starmer, has also acknowledged that the court has provided clarity and said there is a need to ensure guidance is “in the right place according to that judgment.”

Key issues for employers arising from this decision include:

• Single sex spaces – employers with single-sex policies in relation to changing rooms and toilet facilities will need to review their policies to ensure compliance, whilst ensuring all staff feel safe and respected. Baroness Falkner has said that the updated guidance will give clarity on the use by trans women of women-only toilets or changing facilities.
• Policies and procedures - employers may wish to review their other policies, such as those relating to pregnancy, maternity and family leave and gender identity in light of this decision.  Employers should continue to ensure that all staff, including any trans people, are treated with dignity and protected from discrimination and harassment. They should be mindful of the potential impact the decision may have and may wish to reiterate their commitment to diversity, equity and inclusion for all staff. 
• Comparators in discrimination claims – in discrimination claims involving gender reassignment, the correct comparator is key to determining whether discrimination has occurred. The Supreme Court’s decision in this case is likely to be influential in determining the correct comparator in gender reassignment discrimination cases going forwards. 
• Gender pay gap reporting – the decision may also be relevant in terms of gender pay gap reporting. The gender pay gap regulations do not define the terms ‘male’ and ‘female’. There is government guidance on how to record an employee’s gender for gender pay reporting purposes here. This suggests that a person’s gender depends how they self-identify. It may be that this guidance is updated in future in light of this decision. 
• Genuine occupational requirements - where an employer has a general occupational requirement for the person holding a role to be a particular sex, they will be able to lawfully exclude trans people with that acquired gender, even where they hold a gender recognition certificate. Employers should take legal advice to ensure they comply with the requirements around this.
• Positive action - where an employer takes positive action measures aimed at supporting those of a particular sex to overcome disadvantage (where this is allowed), they will be able to lawfully exclude trans people holding a gender recognition certificate in that sex, but should take legal advice on this.
• Service providers, associations and charities - the judgment will also be important in terms of whether employers who are service providers, associations and charities are able to lawfully exclude trans people, regardless of whether they have a full gender recognition certificate, where the Equality Act provides for the provision of separate single-sex services, associations and charities. The EHRC is reviewing its guidance on this issue following the Supreme Court’s judgment.

If you would like more information or advice on the implications of this case, please get in touch with your usual contact.

For Women Scotland Ltd v Scottish Ministers