Britain's equalities watchdog is examining guidance issued to employers by a charity devoted to trans inclusion in business, after a feminist pressure group claimed the materials were "entirely counter to the law".

In a letter to the head of the Equality and Human Rights Commission (EHRC) seen by City AM, Sex Matters alleges that Trans in the City has been misleading its corporate partners about how to enforce their transgender inclusion policies following fresh guidelines from the regulator.

Sex Matters chief executive Maya Forstater said materials published by the charity — whose roster of corporate partners has included the London Stock Exchange, Sky and BP — are "wrong in law", and urged EHRC chair Mary-Ann Stephenson to take "urgent action".

"I wish to draw your attention to a seriously misleading document on the website of a campaign group called Trans in the City, which was recently published in its newsletter," Forstater wrote, singling out the paper's opening statement, which she said was "wrong in law".

In the document, developed in partnership with Robin White KC and inclusion consultant Involve, Trans in the City tells companies to "allow employees to use the facilities they feel most comfortable using".

"Employees that require additional privacy or who feel uncomfortable sharing should feel free to access a universal toilet," the guidelines add.

The EHRC told City AM it was considering the claims made in Sex Matters' letter, adding that it would take "enforcement action where necessary".

Businesses tighten trans policies

The clash underscores the challenge facing employers in the wake of last year's landmark Supreme Court ruling on the definition of a woman. In April 2025, judges in the case brought by the campaign group For Women Scotland against the Scottish ministers decided that a woman should be defined as someone who is biologically female, and that transgender women who were born biologically male should therefore be excluded from women-only spaces.

The EHRC, the body responsible for enforcing equality laws across Britain, has since published a raft of guidance for employers and service providers to help them comply with the Supreme Court's judgment. In advice for service providers that came into effect last month, the watchdog clarified that single-sex spaces such as changing rooms and bathrooms must be organised based on biological sex. Providers are also permitted to offer third spaces for transgender staff or guests to use.

That advice, which followed a similar batch of preliminary guidance for employers, has forced several firms to rip up or tighten their legacy trans inclusion policies, including Coventry Building Society, Aviva and Admiral Insurance. Many blue chips had previously chosen to allow staff to use single-sex spaces based on the gender with which they identified — an approach deemed incorrect by the equalities regulator. The dispute over the Trans in the City guidance highlights how contested the interpretation of that legal landscape remains, with campaign groups on either side pushing regulators and employers toward differing readings of the same judgment.

Forstater's letter also alleges that an example contained in Trans in the City's guidelines is "confusing and misleading". In the case study, a transgender woman is directed by a senior manager to use a male bathroom because of the EHRC guidance. In that scenario, the guidelines state, the employee could sue their employer for harassment, because the instruction — which disclosed her special category data — violated the staff member's "dignity, or creating an intimidating, hostile… or offensive environment".

Under UK GDPR, special category data includes information revealing a person's gender reassignment, which is protected more strictly than ordinary personal data — a distinction central to the disagreement over the case study.

Sex Matters argued that "sex is not special-category data". "This guidance is clearly trying to recreate the situation where single-sex rules can not be communicated or enforced based on the fiction that to do so would 'out' people," the letter said.

Trans in the City chief executive Bobbi Pickard said: "As clearly stated Trans in the City does not provide legal advice however the guidance was created after consultation from several leading legal professionals from our wide membership of global organisations.

"In line with the well documented and long proven benefits of inclusion in business, we believe every person whether they are trans or not, whether they are trans inclusive or whether for whatever reason they do not wish to potentially share facilities with the very few trans people in society, should be able to work in safety, with dignity and privacy. Our guidance supports this goal and highlights some of the risks for employers with the increasing unworkable legal position in the UK."

A spokesman for the EHRC said: "The Supreme Court clarified the law in April 2025, those with duties under the Equality Act should be following the law, updating their policies if needed and seeking independent legal advice where necessary.

"We will monitor compliance with the law and take enforcement action where it is proportionate and necessary."