According to the centuries-old civil code, contracts that are contrary to good morals are deemed invalid.

This has traditionally made it impossible for prostitutes to take action when one of their customers refuses to pay, online news website 20 Minutes reported.

“A man can say in court, yes, I have used the lady’s services – but that was all dirty and immoral, so I’m not paying. And the court must let him off,” Liberal Councillor Caroni told the website.

However a discrepancy exists in that, although considered by some to be “contrary to good morals,” prostitution has been legal in Switzerland since 1942. Switzerland also recovers taxes from those working in the trade.

The law does not set out explicitly what is meant by “good morals” and it is therefore up to the courts to interpret the provision accordingly. Caroni points out that the text was first drafted at a time when social mores and morality were very different from the practices of today.

It is thought that most customers do pay up, perhaps in fear of retribution from the prostitute’s pimps, but many women work alone and are vulnerable to abuse by punters.

While it is unclear how many women this affects, Liberal Councillor Caroni believes it is time to call a halt to such double standards.

“The time is ripe to give prostitutes a legal claim to their agreed wage,” Caroni said.

The reform is backed by other Liberal Councillors, as well as by the Social Democratic member of the Law Commission Jean-Christophe Schwaab and Green Party member Daniel Vischer.

But Swiss People’s Party member Natalie Rickli opposes the action, believing prostitutes should be responsible themselves for collecting their wages.

“They could simply ask for an advance,” she said.