Currently, for a court to hand down a rape conviction in Switzerland, prosecutors have to prove that a perpetrator used force, threats of psychological pressure. This means victims are indirectly required to prove that they defended themselves.

However, this is problematic because paralysis and a state of shock are common reactions to sexual assault.

Read also: One in five Swiss women a victim of sexual assault – study

Now, though, the human rights organization Amnesty International has launched an online petition calling for Switzerland to bring in the type of explicit consent law introduced in Sweden last year, and which already exists in countries including England, Germany and Belgium.

Under this law, participants need to agree in words or clearly demonstrate they want to engage in sexual activity, with passivity not considered a sign of voluntary participation.

 A video promoting the new Amnesty International campaign in Switzerland.

“Sex has to take place voluntarily. Both [parties] have to be clear that the other person wants [sex too]. It is not too much to ask;” said Noëmi Grütter of the Swiss chapter of Amnesty International.

She added this consent could be verbal or non-verbal.

The onus would then be on prosecutors to ask rape or sexual assault suspects how victims had behaved and why they felt consent had been given.

For Greens MP Sibel Arslan the change would represent a paradigm shift in Switzerland.

“Sex would no longer be something that you could take until somebody defended themselves. It would be a clear signal to society,” she told Swiss news site 20 Minuten.

Arslan has now lodged a motion with the Swiss parliament calling for legislation relating to sexual assault to be overhauled to include explicit consent.

In her motion, the Greens MP also called on the government to explain how Swiss sexual assault legislation would be brought in line with Article 36 of the Istanbul Convention, which Switzerland is a signatory to.

Article 36 of the convention calls on parties to introduce laws or other measures that would criminalize non-consensual sex and sexual acts.

Sexologist Martin Bachmann said the greatest challenges with a change to the current Swiss law would involve determining how mutual consent would work in practice and how it could work in a judicial setting.