The UK Supreme Court has ruled that, for the purposes of the Equality Act 2010, the legal definition of “woman” is based on biological sex rather than acquired gender status.
Five judges agreed that transgender women, even those with a gender recognition certificate (GRC), should not be counted as women when legislation requires the representation of both sexes, such as gender quotas on public boards in Scotland (2018 Act). The court ruled that the concept of sex is binary.
The judgment follows a case brought by campaign group For Women Scotland (FWS), which challenged the Scottish government’s policy of including trans women in the 50 percent female quota for public board representation. FWS lost their case but appealed to the Supreme Court.
Judges in the Supreme Court rejected Scottish ministers’ interpretations that trans women do count towards quotas, saying this would create unequal sub-groups among transgender individuals based on whether they hold a GRC. The court said such interpretations would be unworkable and infringe on the rights of others, including those with same-sex attraction.
It concluded that a biological definition of sex is essential for the proper functioning of key provisions in the Equality Act—such as those relating to single-sex spaces, services, sports, communal accommodation, and charities.
Interpreting sex based on GRC status would lead to legal incoherence and practical difficulties, the court said.
A government spokesperson said the ruling brings clarity and confidence for women, and services such as hospitals, refuges, and sports clubs.
However, the court’s decision does not change protections against discrimination on the basis of gender reassignment, which is a protected characteristic under the Equality Act. It does clarify how sex should be interpreted in legal and policy contexts where biological definitions are required.
Jonathan Mansfield, employment law partner at Spencer West, said: “This latest ruling highlights inconsistencies in sex based rights in employment and poses some practical issues for employers. Certain rights which are currently available related to sex such as equal pay will only be available based on biological sex.
“A trans woman, for example, will not have the right to bring an equal pay claim on the basis that she is paid less than a (biological) man. There is specific protection against discrimination for those who have undergone or propose to undergo gender re-assignment. However, this protection does not extend to all those who would be entitled to apply for a GRC where the requirements include a diagnosis or gender dysphoria and having lived in the acquired gender for at least two years among other requirements.”
He said that the Supreme Court decision is consistent with the Equality and Human Rights Commission (EHRC) recommendations but added that more legislative clarification would be needed.
In 2023, EHRC recommended that a biological definition of “sex” in the Equality Act should be adopted as it creates clarity in more areas of legal protection (e.g. data collection) than confusion or disadvantage (e.g. equal pay). However, legislative clarification is necessary as the EHRC noted that society has evolved considerably with regard to matters of protected characteristics of sex and gender re-assignment since the Act came in.
EHRC welcomed the judgment, saying it addressed challenges around maintaining single-sex spaces and the legal clarity needed for rights based on biological sex.
Baroness Kishwer Falkner, EHRC chairwoman, said it has “significant implications for the interpretation of Britain’s equality laws”.
“We will take the outcome of this appeal into account in our ongoing work as the regulator of the Equality Act,” she said. “That includes the development of our revised code of practice which, subject to ministerial approval, is expected to be laid before parliament before the summer recess. We will be working at pace to incorporate the implications of this judgment into the updated code, which supports service providers, public bodies and associations to understand their duties under the Equality Act and put them into practice.”
The EHRC chair added that where this judgment impacts the regulator’s other advice for duty-bearers, such as single-sex services guidance, “we will review it as a matter of urgency and alert users to where guidance has been withdrawn or needs to be updated”.
However, a number of LGBTQ+ and trans advocacy groups expressed concern over the ruling’s impact on transgender rights and inclusion.
Peter Cheese, chief executive of the CIPD, welcomed the Supreme Court’s clarification today.
“This will provide further understanding for individuals and organisations in what has been a difficult area for employers to interpret and find the right balance, recognising the rights and beliefs that need to be upheld for all,” he said.
“Employers will need to ensure that their policies and approaches are up to date with today’s legal clarification of the position in the UK. However, there will remain legal and practical issues for employers to work through to support inclusion, dignity, and fairness at work and ensure all colleagues are protected from discrimination and harassment.
“We hope that today’s ruling will simplify some of the guidance and discussion in this space and as the CIPD, we are updating our own content and resources for HR professionals where needed.”
