ANNE RUZYLO, a 52-year-old trade unionist, had been a member of the Labour Party for many years. But at a meeting in Cambridge on November 23rd she cut up her membership card before a cheering audience. The gathering, organised by a group called A Woman’s Place, was held to discuss government plans to amend the Gender Recognition Act to make it easier for people to change their gender. Ms Ruzylo worries that this may pose a risk to the safety of women. For voicing her fears, she says, she has been the victim of a smear campaign within the party and branded “transphobic”.

Hers is the latest skirmish in a war on the left about the rights of transgender people, who identify as a gender that is different from the sex of their birth. Linda Bellos, also at the Cambridge meeting, was recently disinvited from speaking to a student society after revealing that she planned to discuss the changes to the law. Helen Steel, another speaker, says she was harassed after defending the right of two women to distribute leaflets about the reforms at a book fair. The broader debate about transgender rights has become so acrimonious that A Woman’s Place kept the location of its recent meeting secret.

Currently, those wishing to change their legal gender must have a diagnosis of gender dysphoria, the distress arising from the sense that their true gender does not match their sex at birth, and have lived according to their chosen gender for two years. The government would scrap those requirements and have applicants “self-declare” their gender identity instead.

It also wants to revise the Equality Act, which allows organisations running gender-sensitive services—from hospital wards to prisons—to discriminate on the basis of sex, as long as it is “a proportionate means of achieving a legitimate aim”. It is legal to turn away a transgender woman from a domestic-violence shelter, for instance, if her presence would frighten others. The government proposes to ditch these exemptions for trans people.

Some feminists think such changes would threaten the safety of women. Ms Ruzylo worries that abusive men would find it easier to enter women-only spaces if they could change gender by declaration alone. The worry is not merely hypothetical. Ms Ruzylo cites the case of Paris Green, a transgender woman from Scotland, where self-declaration is, broadly, in place. Convicted of murder as a man, Ms Green was permitted to transfer to a women’s prison, before being moved after having sex with female prisoners. James Barrett, the lead clinician at the National Health Service’s gender-identity clinic in London, says that half of the prison service’s transgender inmates have been convicted of sexual offences (though he cautions that the numbers are small).

Yet the case of Vicky Thompson lends weight to the other side of the argument. Ms Thompson, a transgender woman who was convicted of theft, failure to surrender to court and breach of a suspended sentence, told friends she would kill herself if she was sent to a male prison. She was, and two years ago she committed suicide. Ms Ruzylo, a former prison officer, believes that anyone born male should not be imprisoned in a women’s jail. Others at the meeting thought cases should be evaluated on their merits, as under today’s law. Whatever the government does, the argument will rage on.

Correction (December 4th, 2017): An earlier version of this story muddled the case of Vicky Thompson with that of Joanne Latham. Both were transgender women who committed suicide in prison in 2015. But it was Ms Thompson who had earlier threatened to kill herself if she was not sent to a women's prison—not Ms Latham, as our article said. Sorry.

Correction (December 6th, 2017): We also said that Paris Green had twice been moved back to a men's prison. In fact she was moved back only once, to a women's facility within a men's prison.