WOMEN’S rights groups celebrated today after Californian Governor Jerry Brown signed a Bill making the state the first in the US to adopt a “Yes means Yes” policy on sexual consent.

The Bill, presented by Los Angeles Democrat Senator Kevin de Leon, adopts new requirements for universities to follow when investigating sexual assault.

Mr de Leon said the new rules will mean a sea change in preventing and investigating rape allegations — replacing a previous emphasis on “No means No” with a need for “affirmative, conscious and voluntary agreement to engage in sexual activity.”

Under the law nobody who is drunk, drugged, unconscious or asleep can grant consent to sexual activity.

Critics say it could cause problems for universities over grey areas such as when two people under the influence of alcohol agree to sexual intercourse.

But advocates note consent does not have to be verbal and is an important challenge to the idea that victims should have actively resisted assault to have a valid complaint.

“The affirmative consent standard will help change the revictimising, insensitive reporting procedures, instead allowing students to seek help and hold perpetrators to account,” said University of

California Associated Students Sexual Assault Commission chairwoman Meghan Warner.

It also mandates additional training for investigators to stop victims being asked inappropriate questions and insists that they are given access to counselling and appropriate healthcare.