California has adopted a historic 'yes means yes' rule for investigating campus sex assault complaints

A bill that makes California the first US state to define when "yes means yes" and adopt requirements for colleges to follow when investigating sexual assault reports has been signed into law.

The measure was approved last month as states and universities across America are under pressure to change how they handle rape allegations.

Campus sexual assault victims and women's advocacy groups delivered petitions to California governor Jerry Brown's office on September 16, urging him to sign the bill.

State senator Kevin de Leon says the legislation will begin a paradigm shift in how college campuses in California prevent and investigate sexual assaults.

Rather than using the refrain "no means no," the definition of consent under the bill requires "an affirmative, conscious and voluntary agreement to engage in sexual activity".

"Every student deserves a learning environment that is safe and healthy," Democrat Mr de Leon said. "The State of California will not allow schools to sweep rape cases under the rug. We've shifted the conversation regarding sexual assault to one of prevention, justice, and healing."

The legislation says silence or lack of resistance does not constitute consent. Under the bill, someone who is drunk, drugged, unconscious or asleep cannot grant consent.

Politicians say consent can be non-verbal and universities with similar policies have outlined examples as a nod of the head or moving in closer to the person.

Advocates for victims of sexual assault supported the change as one that will provide consistency across campuses and challenge the notion that victims must have resisted assault to have valid complaints.

"The affirmative consent standard will help change the re-victimising, insensitive reporting procedures, instead allowing students to seek help and hold perpetrators accountable," said Meghan Warner, chairwoman of the University of California Associated Students Sexual Assault Commission.

"This is a major victory for all California students, not just survivors. I hope the rest of the nation will follow suit."

The bill requires training for staff reviewing claims so that victims are not asked inappropriate questions when filing complaints. The bill also requires access to counselling, health care services and other resources.

When politicians were considering the bill, critics said it was overreaching and sends universities into murky legal waters. Some Republicans in the assembly questioned whether state-wide legislation was an appropriate venue to define sexual consent between two people.

There was no opposition from Republicans in the state senate.