California’s Gov. Jerry Brown on Sunday signed a law requiring all state colleges to adopt a policy of unambiguous, affirmative consent by students engaged in sexual activity, part of a nationwide effort to curb sexual assault on U.S. campuses.

The state’s so-called "yes means yes" law will be the first in the nation to make affirmative consent language a central tenet of school sexual assault policies, proponents said.

The legislation defines consent as "an affirmative, conscious and voluntary agreement to engage in sexual activity." It also states that silence and a lack of resistance do not signify consent and that drugs or alcohol do not excuse unwanted sexual activity.

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.

"This is amazing," said Savannah Badalich, a student at UCLA, where classes begin this week, and the founder of the group 7000 in Solidarity. "It's going to educate an entire new generation of students on what consent is and what consent is not... that the absence of a no is not a yes."

The bill requires training for faculty who review complaints so that victims are not asked inappropriate questions when filing complaints. The bill also requires access to counseling, health care services and other resources.

State lawmakers last month approved the bill by Sen. Kevin de Leon, a Los Angeles Democrat, as states and universities across the U.S. are under pressure to change how they handle rape allegations. Campus sexual assault victims and women's advocacy groups delivered petitions to Brown's office on Sept. 16 urging him to sign the bill.

De Leon has said the legislation will begin a paradigm shift in how college campuses in California prevent and investigate sexual assaults.

The law applies to all California post-secondary schools, public and private, that receive state money for student financial aid. The California State University and University of California systems backed the legislation after adopting similar consent standards this year.

In January, President Barack Obama vowed to make the issue a priority. He announced a task force chaired by Vice President Joe Biden that created a website providing tips for filing complaints, www.notalone.gov, and issued areport in May naming 55 colleges and universities across the country facing investigation for their responses to sexual abuse and violence. The University of California, Berkeley was included on the list.

The White House Council on Women and Girls reported (PDF) that nearly 1 in 5 college women is sexually assaulted by the time she graduates, with just 12 percent of them reporting the assaults — a much lower rate than the estimated 40 percent of assaults that are reported by the general population, according to the Department of Justice.

In addition, students from a number of colleges and universities — including the University of California at Berkeley and the University of Southern California, Dartmouth College, Columbia University, Harvard College, Occidental College, Swarthmore College — have filed complaints in the last year that their schools violated the Clery Act and Title IX of the Civil Rights Act by mishandling their sexual assault cases.

Al Jazeera and wire services