The old sexist joke about women and politics goes that the place of a woman in the movement is prone. For the Liberal Democrats, until 2015, the place of a woman was in an unsafe seat if she made it into parliament at all – of the three main parties, the Lib Dems had the fewest female MPs, and they were concentrated in the party’s most precarious constituencies.

When the Lib Dems collapsed at the polls, it became a party of men. And a party of men is exactly who you’d expect to come up with a policy of totally decriminalising prostitution, likely to be adopted at the Lib Dems’ spring conference.

Of course, they’re Lib Dem men, so there’s a veneer of do-gooding. Some of it is even actually good. The policy would quash all historic convictions for prostitution, removing a huge burden from women in or exiting prostitution; and it also includes provisions to expand services for those who want to stop selling sex, with plans to offer support in health, housing and education.

If that was the whole of the policy, the Lib Dems would be doing something unambiguously positive – even radically feminist. Criminal records that bar women from legal employment, summary fines that can only be paid by taking more punters, and short prison sentences that disrupt women’s lives without offering any kind of positive interventions all help to snare women in prostitution by punishing them for being prostituted.

In pictures: Sex workers protest in Paris Show all 8 1 /8 In pictures: Sex workers protest in Paris In pictures: Sex workers protest in Paris A protester (R) holds a sign reading 'Prostitutes with fists raised against the penalisation of clients!' during a demonstration by sex workers and supporters near the French National Assembly in Paris In pictures: Sex workers protest in Paris A protester wears a hat rimmed with red roses during a demonstration by sex workers and supporters near the French National Assembly in Paris In pictures: Sex workers protest in Paris Sex workers hold signs during a protest against new bill against prostitution and sex trafficking In pictures: Sex workers protest in Paris Transgender sex workers protest against a parliamentary vote to enforce the penalisation of solicitation, near the Assemblee Nationale (French parliament) in Paris In pictures: Sex workers protest in Paris A protester wears a mask during a demonstration by sex workers and supporters near the French National Assembly in Paris In pictures: Sex workers protest in Paris Protesters wear masks during a demonstration by sex workers and supporters near the French National Assembly in Paris, as French lawmakers take part in a final debate on a bill that would make it illegal to pay for sex. French lawmakers were poised on April 6 to pass a controversial law that makes it illegal to pay for sex and imposes fines of up to 3,500 euros ($3,970) on prostitutes' clients In pictures: Sex workers protest in Paris Protesters hold up their fists and chant slogans during a demonstration by sex workers and supporters near the French National Assembly in Paris In pictures: Sex workers protest in Paris Protesters hold a banner reading 'Don't liberate me, I'll take care of it myself!'

Despite Crown Prosecution Service guidelines saying that prostitution should be “addressed as sexual exploitation within the overall CPS violence against women strategy”, the criminal justice response in practice is a vicious double bind. The role of prostitute is basically the role of scapegoat: she exists so men can take out their urges for dominance on someone, and then she must pay the penalty for what is done to her.

As the CPS guidelines suggest, prostitution law doesn’t only target those in prostitution. In fact, used properly, its targets should primarily be the pimps and the punters: the men who use women for sexual gratification and financial gain. And it’s where the Lib Dem policy touches on the buyers and the sellers, rather than the bought and sold, that its weaknesses become obvious. Because the Lib Dems also want to wipe all convictions for kerb-crawling and brothel-keeping, allowing the exploiters the same clean start as the exploited.

The idea that this would make prostitution safe is based on the bizarre misapprehension that the only thing making prostitution unsafe is the law. Actually the thing that makes prostitution unsafe is men, and without men to pay for sex there would be no prostitution.

The Femicide Census has revealed that when women in prostitution are killed, their killer is usually a client. In general, women are most likely to be killed by a current or former partner – who in the case of prostitution may well actually be the woman’s pimp, dressing his coercion up as romance.

MPs involved in sex scandals Show all 9 1 /9 MPs involved in sex scandals MPs involved in sex scandals Mark Oaten Mark Oaten resigned as a senior member of the Liberal Democrats in 2006 after the News of the World revealed he had paid rent boys to perform sexual activities on him. He openly spoke about the affect it had on his family life and career in his book 'Screwing Up' Rex Features MPs involved in sex scandals Simon Danczuk He admitted to sending inappropriate texts to a 17-year-old Sophena Houlihan and calls are being made for him to resign from his role as Labour's Rochdale MP. He reportedly blamed a drinking problem on his sexually explicit messages Reuters MPs involved in sex scandals Brooks Newmark Brooks Newmark resigned form his role as a Conservative member of parliament for Braintree, Essex in 2014 after being caught sending explicit photos, involving paisley pyjamas, to an undercover journalist Rex MPs involved in sex scandals Lord Lambton Lord Lambton, a Conservative MP, was pictured in bed with two prostitutes and smoking a joint in 1973, the same year he resigned. He initially denied it, but later said he had a multitude of affairs after he was bored with his job Rex Features MPs involved in sex scandals Bob Blackman Robert Blackman, a Conservative MP had an 11 year affair with another Conservative councillor, which came out after he said marriage can only work between “one man and one woman” Rex Features MPs involved in sex scandals Nigel Griffiths Nigel Griffiths, former MP for Edinburgh South, admitted cheating on his wife of 30 years with an un-named woman after a Sunday tabloid produced photographs of the affair on a sofa in his Parliamentary office Rex Features MPs involved in sex scandals John Major Former Prime Minister John Major and former MP Edwina Currie’s four year affair began in 1984 and lasted four years. The affair came out in 2002 when Ms Currie serialised her diaries in The Times BBC News/Getty Images MPs involved in sex scandals John Prescott The then deputy Prime Minster to Tony Blair had a two year affair with his appointments secretary, Tracey Temple 43, came to light in 2006. He said: "I did have a relationship with her which I regret. It ended some time ago" Getty MPs involved in sex scandals Paddy Ashdown Paddy Ashdown, former leader of the Liberal Democrats, was nicknamed "Paddy Pantsdown" in 1992 after he was forced to disclose a five year affair with his secretary, Tricia Howard. He admitted the affair to his wife BBC

Everywhere that total decriminalisation is tried, women are hurt. When Leeds designated a particular industrial area as a managed zone “for prostitutes to work without fear of police action”, it became the site of Daria Pionko’s murder. When Germany attempted to make prostitution into “a job like any other”, it brought the rise of megabrothels, where women can be abused on a battery basis. Amsterdam’s red light district didn’t free up sex workers to become vaginal entrepreneurs, but it did make the city a centre for trafficking.