(CNN) -- Thousands of freshmen at the University of California-Berkeley swiped their student cards last week at the doors of Zellerbach Hall and filed into the dark auditorium for one of the few mandatory sessions in their three-week welcome program.  Dealing with sexual harassment, alcohol and stress were on the 90-minute "Bear Pact" agenda -- much of what you might expect in a freshman orientation, said 17-year-old Alexandra Yoon-Hendricks, who attended one of three sessions offered.  One topic, however, caught her by surprise: the definition of sexual consent, the way we let others know what we're up for, be it a good-night kiss or the moments leading up to sex.  A slide projected onstage defined consent through three "pillars": "Knowing exactly what and how much I'm agreeing to; expressing my intent to participate; deciding freely and voluntarily to participate."  Instead of waiting for your partner to say "no," speakers onstage told students, you should seek an explicit "yes." It could come in the form of a smile, a nod or a verbal yes, as long as it's unambiguous, "enthusiastic" and ongoing.  To Yoon-Hendricks, a staff writer for the teen publication Sex, Etc., it was a refreshing stance for a school to endorse.  "I loved hearing that, because I'd never really heard people describe consent in that manner before," she said. "Instead of saying 'no means no,' 'yes means yes' looks at sex as a positive thing."  It requires a fundamental shift in how we think about sexual assault. It's requiring us to say women and men should be mutually agreeing and actively participating in sexual behavior.Denice Labertew, California Coalition Against Sexual Assault  It's a message students across the country are hearing as they return to campus for a new semester. Often referred to as affirmative consent, it's the concept of both parties agreeing to sexual conduct, either through clear, verbal communication or nonverbal cues or gestures.  "There are lots of ways to express 'yes.' My favorite is 'yes,'" a speaker told the Berkeley freshmen.  California might become the first state to make affirmative consent law. Senate Bill 967 would amend the education code to require schools whose students receive financial aid to uphold an affirmative consent standard in disciplinary hearings and to educate students about the standard. The legislature sent the bill to Gov. Jerry Brown last week.  The legislation has the support of victims' rights groups, violence prevention groups and the University of California System. But critics worry it could define a great deal of sexual activity as "sexual assault" and undermine due process rights of the accused.  Even if Brown vetoes the legislation, consent will still be defined on the University of California's 10 campuses as an "affirmative, unambiguous, and conscious decision by each participant to engage in mutually agreed-upon sexual activity."  MORE: Why vomiting on your attacker won't prevent rape  What that looks like in practice is harder to explain, leaving institutions grappling with how to make the policy more meaningful than words in a student handbook.  "There's varying language, but the language gets to the core of people having to communicate their affirmation to participate in sexual behavior," said Denice Labertew of the California Coalition Against Sexual Assault. "It requires a fundamental shift in how we think about sexual assault. It's requiring us to say women and men should be mutually agreeing and actively participating in sexual behavior."  It's a shift schools have endorsed before with mixed results.  Ohio's Antioch College became a target of national mockery after revising its Sexual Offense Prevention Policy in 1993 to require that students give ongoing verbal consent at each stage of intimacy.  The policy reads today much as it did then: "Consent means verbally asking and verbally giving or denying consent for all levels of sexual behavior."  Consent is required regardless of the parties' relationship, prior sexual history or current activity ("Grinding on the dance floor is not consent for further sexual activity," the policy reads). It cannot be given if the person is intoxicated, unconscious or asleep.  Under this legislation, students who are or may become sexually active must now worry about documenting that they obtained consent.Joseph Cohn, Foundation for Individual Rights in Education  The rule was mocked in a "Saturday Night Live" skit featuring Phil Hartman as the host of the game show "Is It Date Rape?" The "date rape players" acted out encounters that Antioch students (played by Shannen Doherty and Chris Farley) called out as "date rape" or "not date rape."  The "date rape players" talked like "robots," using cold and clinical language, said Louise Smith, Antioch dean of community life. In reality, "good communication between sexual partners can be fun, even sexy," she said.  "If you think about it not in the SNL kind of way, but as a conversation that's ongoing as things progress, it can work," Smith said.  The school, which closed in 2008 and reopened in 2011, has no empirical way of measuring the policy's success, said Smith, an Antioch alum. But the school feels vindicated by SB 967 and renewed dialogue around consent.  "Despite the fact we were ridiculed, we were extremely proud of this policy. We felt like it was forward-thinking and in line with our values about social justice, equality and health."  Meanwhile, affirmative consent continues to be fodder for sitcoms and sketch comedy shows, highlighting the "profound disconnect between the policy's bureaucratic requirements" and the reality of human sexuality, said Joseph Cohn, legislative and policy director for the Foundation for Individual Rights in Education, a legal advocacy group that has come out against the legislation.  The disconnect underscores "the serious difficulty that passage of SB 967 would present to campus administrators across California," he said. "Under this legislation, students who are or may become sexually active must now worry about documenting that they obtained consent, because proving affirmative consent is the only way to defend oneself before a campus tribunal."  Rewriting the rules of consent  It's no laughing matter to survivors, feminists and prevention specialists, who have long pushed for schools to enforce some form of affirmative consent policy, not only as the moral code governing student conduct, but the standard of proof used in disciplinary proceedings.  Don't miss out on the conversation we're having at CNN Living.  for the latest stories and tell us what's influencing your life.  Now it's starting to gain traction on college campuses amid pressure from advocacy groups and the federal government to do more to prevent sexual violence.  Schools nationwide are in the process of rewriting or have already rewritten their sexual assault policies, procedures and prevention education programs to meet standards in the Campus Sexual Violence Elimination Act, known as the Campus SaVE Act. That took effect in 2013 as part of the reauthorization of the Violence Against Women Act, said Tracey Vitchers with Students Active for Ending Rape, which assists student-led campaigns to reform college sexual assault policies.  More: Violence Against Women Act shines light on same-sex abuse  The White House further signaled its support for the issue this year through the formation of the Task Force to Protect Students From Sexual Assault. Its goal is to help schools improve policies and protocol for preventing and dealing with sexual misconduct so they comply with the Campus SaVE Act.  One of the task force's recommendations for revising sexual misconduct policies included defining consent as a "voluntary agreement to engage in sexual activity." Past consent should not imply consent, nor should silence or the absence of resistance, the guidelines recommend.  To reach compliance with the Violence Against Women Act, the California State University and University of California systems in February adopted standards similar to those in SB 967, including affirmative consent, spokeswoman Dianne Klein said.  Having an affirmative consent standard changes the dynamic because we're not automatically assuming that if someone didn't say no, it means yes.Berekeley student Sofie Karasek  "We've been working on these issues for quite a while. Is it perfect? No. But we are confident that we are doing everything we can and will continue to do so."  Berkeley also was revising its orientation program before the White House task force recommendations, based on student feedback and guidance from the federal government, spokeswoman Janet Gilmore said. In addition to Bear Pact, students are required to take online awareness-building programs on alcohol use and sexual harassment.  More: Survivor-led activist movement leads fight against campus rape  But is it enough? The sexual harassment component of Bear Pact evolved from existing consent education workshops offered at Berkeley since 2011 called "EmpowerU." The smaller, in-person workshops covered affirmative consent by walking through various scenarios, followed by group discussions.  While making Bear Pact mandatory and emphasizing affirmative consent are positive steps, some worry that expanding the presentation into a large lecture format reduces its effectiveness. For Bear Pact, the 90-minute EmpowerU workshop was compressed into a 45-minute lecture with no time for discussion.  Berkeley student and Bear Pact speaker Meghan Warner would like to see consent education continue beyond orientation and sexual harassment workshops and into classrooms and academic curricula.  "We still have a long way to go," said Warner, who works in sexual violence prevention through a number of roles with the Associated Students of the University of California and the Greek System.  "I think it's a great step in the right direction, but I don't think it's sufficient to educate someone for the rest of their life."  Creating positive models of consent  Typical lessons about consent focus on what it does not look like. Most students learn at some point in their postsecondary careers that by law, consent cannot be given under the influence of drugs or alcohol or if someone is asleep or unconscious. In other words, sex under the influence can be considered nonconsensual, which is the definition of rape.  Through presentations and workshops, social media campaigns and fliers posted on campus, schools also are trying to impress upon students that consent should be "enthusiastic," "voluntary" and "unambiguous." It can even be "sexy."  But affirmative consent rules won't stop someone intent on committing sexual assault. Sexual violence is still a problem even at schools that promote affirmative consent, including Berkeley. Berkeley is one of 76 schools under investigation by the Department of Education's Office of Civil Rights for violations of Title IX, the federal law that grants students access to education free of gender-based discrimination and harassment.  Enforcing an affirmative consent standard alone in schools will not fix the system, said Berkeley senior Sofie Karasek, one of 31 students who filed a Title IX complaint against the school in February. It takes a multipronged approach: trained counselors to support survivors, investigators to thoroughly examine cases, and a timely hearing process -- all required under federal law and included in SB 967.  People might say it's impractical or ridiculous in reality, but the possible end of doing something that's not something someone wants is a frightening possibility.Berkeley student Joshua Deng  The affirmative consent clause of SB 967 generates headlines, but supporters of the bill champion its comprehensive approach, which mirrors Title IX requirements. SB 967 also requires schools to implement comprehensive prevention programs and survivor-centered sexual assault response policies and protocols. It calls on schools to form partnerships with community organizations to assist survivors.  The affirmative consent standard helps by shifting the burden in disciplinary hearings from the complainant, who had to prove assault occurred, to the accused, who must show that he or she sought consent, Karasek said.  "There's this underlying assumption, unlike in any other crime, that survivors are lying or overexaggerating," Karasek said. "Having an affirmative consent standard changes the dynamic because we're not automatically assuming that if someone didn't say no, it means yes."  The flipped dynamic is what concerns critics of SB 967. Under an affirmative consent standard, sexual activity is sexual assault unless the accused can prove that the accusing party consciously and voluntarily agreed to engage in sexual activity. Moreover, the accused student must prove that the consent was ongoing, said Cohn, with the Foundation for Individual Rights in Education.  "When 'affirmative consent' becomes law, there will be no practical, fair, or consistent way for colleges to implement these newly mandated prerequisites for sexual activity," Cohn said.  "It is impracticable for the government to require students to obtain affirmative consent at each stage of a physical encounter, especially if students must later prove they successfully did so in a campus hearing. In reality, requiring students to obtain affirmative consent will render a great deal of legal sexual activity 'sexual assault.'"  To some young men, however, mutual consent is already a familiar concept. Berkeley freshman Alexander Vu attended the same Bear Pact session as Yoon-Hendricks. To him, it sounded like a lot of the same concepts from high school health class.  "It was a good way to reinforce the idea of mutual consent, but it wasn't anything I hadn't heard before," the 18-year-old said.  Is it something he would practice? "Yes, absolutely," he said. "It seems like a good foundation for a healthy, mutually respectful relationship."  Berkeley freshman Joshua Deng, who also attended the Bear Pact presentation, said he supports the idea of affirmative consent both as a school policy and a rule of thumb to cover him from allegations of wrongdoing.  "I don't want to be forcing someone into a position they're going to be uncomfortable with," he said. "People might say it's impractical or ridiculous in reality, but the possible end of doing something that's not something someone wants is a frightening possibility."  He stopped short, though, of fully backing affirmative consent as state law.  "I'd have to do more research," he said. "Making a law for anything has huge implications and there's got to be a lot of thinking that goes into that."  In evaluating sexual misconduct claims, SB 967 calls for schools to apply a "preponderance of evidence" standard, similar to Title IX. It's a lower standard of proof, used in civil cases, instead of the "beyond a reasonable doubt" bar used in criminal trials.  That's another point of contention for people who say SB 967 undermines due process rights by subjecting the accused to a lower culpability threshold without the protections offered by criminal and civil courts -- such as the mandatory exchange of evidence known as discovery and restrictions on hearsay and prior bad act evidence.  "Those accused in campus tribunals are generally denied these protections -- but nevertheless are subject to life-changing sanctions, based on little more than a hunch by campus court participants that one person's story is slightly more credible," Cohn said.  Like Berkeley, Columbia University in New York has been the subject of negative publicity in the past year over its handling of sexual misconduct. Just this week, a Columbia student made headlines for vowing to carry around a mattress on which she claims she was raped, until her alleged attacker is disciplined.  Columbia rolled out a new mandatory, two-part workshop for freshmen this semester on sexual violence and gender-based misconduct as part of its New Student Orientation Program.  "Since the beginning of this year the university has been moving on multiple fronts both to respond to student concerns and reflect the changing guidance from the U.S. Department of Education on this issue," spokeswoman Victoria Benitez said.  Student activists asked administrators to revise Columbia's "Consent is Sexy" workshop last year to make it mandatory and more serious in tone. Attendees told the Columbia Spectator that the presentation focused on defining consent and walking through different scenarios of sexual harassment.  Consent was defined as "an enthusiastic yes that was gained without the use of intimidation or coercion," one attendee told the campus newspaper. The information was thorough and explicit, attendees said, even if it was a little boring and repetitive at times.  Orientation for many students began before they arrived at Columbia, Benitez said. Through newsletters and a video, the school introduced students to its "Step Up" and "Make a Difference" campaigns on sexual harassment prevention and bystander intervention.  If you're in a healthy sexual relationship, wouldn't you want your partner to be as interested in what you're doing as you are?  One handout on "gauging consent" offers examples of signs that you should stop, such as "you or your partner are too intoxicated to gauge or give consent" or "you hope your partner will say nothing and go with the flow."  Signs you should pause and talk might be that "you feel like you are getting mixed signals" or "you are not sure what the other person wants."  Another handout provides students with suggested ways to ask for consent: "Does this feel good?" "Would you like me to...?" "Do you want to keep going?"  Framing consent this way serves as a reminder that it can also apply to committed relationships. After all, the vast majority of people who are sexually assaulted know their attacker, and often have a relationship with them, said Laura Palumbo with the National Sexual Violence Resource Center.  Even couples in healthy relationships can benefit from consent, she said.  "If you're in a healthy sexual relationship, wouldn't you want your partner to be as interested in what you're doing as you are? Wouldn't you want the move you're making to be satisfying to your partner?" she said.  "Our culture is saturated with sex, but we're not given great info about how to talk effectively about sex. We see it on billboards and TV but when we're talking about sexual wants, needs and boundaries, people don't have good language or models for how to approach that."  Time will tell if the orientation workshops, posters and fliers have a lasting impact on students. Yoon-Hendricks said the session at Berkeley made an impression on her, but she acknowledges there was a lot of snickering in the crowd around her.  "To kids who giggle every time someone says sex, I don't think it was as informative as it could've been," she said. "But they did a good job of illustrating the point in a short period of time."  One thing missing from the presentation? More transparency about Berkeley's history with the issue.  "I think they're trying very, very hard to illustrate the problem on campus. However, they didn't even acknowledge fact that UC system is in trouble because of this issue," she said.  "Full disclosure would've been appreciated from most of the students."
California SB 967 requires students to seek "affirmative consent" from partners at each stage of sexual activity. How does "yes means yes" really work?