In California this week, “no means no” became “yes means yes.”

The distinction between the two might seem elusive, but the idea of “affirmative consent”—a concept which Governor Jerry Brown signed into law for the state's college campuses last week—can make a huge difference in the adjudication of cases of sexual assault.

The California bill describes affirmative consent as “affirmative, conscious, and voluntary agreement” from both partners to sexual activity. This means that an individual must openly express, verbally or non-verbally, his or her desire to take part in a sexual act just before the act takes place. According to the law, those who are unconscious or intoxicated cannot consent, and consent to one type of contact (kissing, for example) does not imply consent to another type (such as sexual intercourse). The law is the first in the nation to officially embrace an affirmative consent policy, and we hope others are soon to come.

Legal affirmative consent policies bring clarity to a tough juridical matter. Before, sexual assault prosecutions and defenses alike ran into trouble in the courtroom because policies were too vague—it was difficult for those on the bench to understand what constituted assault, and what constituted bad communication. Affirmative consent policies help to clear up that question: Without a clearly expressed intention from all parties to engage in sexual activity, that activity is legally impermissible. A more transparent policy should prove a boon to the accuser and the accused alike.

Of course, no policy will neatly resolve all confusion, but affirmative consent is certainly a step in the right direction. The policy does not only aid in the courtroom, but it may also keep some assaults from occurring in the first place. With proper education in affirmative consent, perpetrators who may have previously waited for a “no” perhaps now will wait for a “yes” instead.

What’s more, centralized policies help individuals understand what consent means and how to go about obtaining it, no matter where they are. The more states that tread the trail California has grazed, the better.

In the past, we have expressed our wish for Harvard to adopt an affirmative consent policy of its own. This summer, the University updated its policies, but failed to establish such a policy on the grounds that “there is no standard definition of affirmative consent.” California has provided such a standard, and we hope to see states and schools—including Harvard—across the nation follow suit.