Lib Dems face conference vote to change rules on women-only roles after Supreme Court ruling

Liberal Democrat delegates at the party's annual conference in Bournemouth are expected to vote on Saturday on a motion that would prevent trans members from filling roles reserved for women, after campaigners said current diversity rules may breach the Equality Act.

The motion, brought by pressure group Liberal Voice for Women, seeks to remove "self-identify" wording from federal quota rules that currently require at least 40% of roles on federal bodies to be held by people who "self–identify as men or nonbinary people, and self–identify as women or non–binary people respectively." LVW says that formulation could allow all seats reserved for women to be filled by trans women—people assigned male at birth—and so leave biological women without representation.

Liberal Voice for Women is urging delegates to amend the rules so that the quotas require that at least 40% of positions be held by "men" and "women" rather than those who "self-identify." The group has commissioned legal advice that it says indicates the party's current policy is inconsistent with a Supreme Court ruling earlier this year clarifying the meaning of "woman" and "sex" in the Equality Act 2010.

Dr Zoe Hollowood, chairwoman of Liberal Voice for Women, said the party "cannot continue to be derailed by a vocal and extremist group ... who tend to dominate these proceedings at conference." She said the legal advice, from a King's Counsel, advised the party to "put its house in order" to ensure compliance with the law.

Liberal Democrat leader Sir Ed Davey has said the party accepts the Supreme Court ruling, but has also reiterated his personal view that "a trans woman is a woman." The motion notes that women are underrepresented on key party governance bodies and cites figures showing twice as many men as women on the federal council and the English council.

The Supreme Court's April ruling found that the words "woman" and "sex" in the Equality Act 2010 refer to biological women and biological sex. The Equality and Human Rights Commission has said the ruling has effect and is binding and has urged organisations to amend policies and practices where necessary. The commission's updated code of practice and other guidance on trans people's access to single-sex spaces have been delayed and are under consideration by ministers; once approved the government must lay the draft code before Parliament for 40 sitting days before it can be brought into force.

The dispute reflects broader divisions within the party between the leadership and some members on transgender rights. Internal and external polling cited by campaigners and commentators has suggested the membership is less inclined than the leadership to support changes to laws and medical guidance relating to gender change and to prescribe hormone treatments for under-18s. A YouGov poll earlier in the year found 61% of respondents backed the law as it stands, 17% thought rules on changing gender were too lax, and 14% wanted the process made harder. Less than a quarter of members polled supported prescribing puberty blockers or hormones to under-18s.

Women and equalities spokeswoman Lisa Smart has criticised interim EHRC guidance in Commons remarks earlier this month, describing it as "crackers," while party figures including Sir Ed Davey have tried to balance acceptance of the court's legal finding with statements of support for transgender people.

The conference vote will determine whether the Liberal Democrats alter their internal rules ahead of any finalised EHRC code. If delegates approve the amendment proposed by Liberal Voice for Women, party procedures would be changed to reflect quotas based on the terms "men" and "women." If the amendment is defeated, the current self-identification language would remain in place pending any further legal or regulatory developments.

Delegates and party officials have said the outcome could have immediate effects on the composition of federal bodies and on how vacancies reserved for women are filled. The party has been advised to align its governance arrangements with the law as clarified by the Supreme Court and with forthcoming EHRC guidance once it is finalised and laid before Parliament.