In May, Sweden became the 10th country in Europe to recognize that sex without consent is rape. The new legislation, which passed by a majority vote in Parliament and goes into effect in July, has been hailed as a huge victory by women’s rights activists.

"The biggest value of this law is normative,” Amnesty International’s Anna Blus told Newsweek, “making society realize what rape is and, hopefully, preventing rape in this way.”

Previously, in order for a prosecutor to prove that a rape had occurred, he or she had to show evidence that the perpetrator used force, threatened to use force, or had taken advantage of someone in a vulnerable situation. Now, under the new law, in order for sexual activity to be considered legal, a person needs to explicitly agree or otherwise make it clear they want to participate. As Swedish Prime Minister Stefan Löfven said at a news conference last year supporting the change in law: “It should be obvious. Sex should be voluntary. If it is not voluntary, then it is illegal. If you are unsure, then refrain.”

The change in Sweden’s rape law is an example of the global movement to pass affirmative consent policies. Here in the US, a number of state and citywide consent reform initiatives are currently under consideration; California is the only state to pass “yes” means “yes” legislation, or the notion that both parties must consciously, explicitly, and voluntarily agree to engage in sex acts, for college campuses.

But what exactly is consent? In jurisdictions across the country, there’s actually little consensus on what counts as consent. In fact, half of the states in the US—including Mississippi, Georgia, Idaho, and North Carolina—don’t explicitly define consent in their statutes at all.

“One person’s idea of consent is that no one is screaming or crying,” Erin Murphy, a professor at New York University School of Law, told the Associated Press in December. “Another person’s idea of consent is someone saying, ‘Yes, I want to do this.’ And in between, of course, is an enormous spectrum of behavior, both verbal and nonverbal, that people engage in to communicate desire or lack of desire.”

For example, in the case of Brock Turner—the former Stanford student convicted of sexually assaulting a woman behind a dumpster—his attorneys tried to argue that the victim had consented to digitally penetrative sex, even though she was intoxicated. “I asked her if she liked it,” Turner testified, “and she said, ‘uh-huh.’” In California, consent is defined as “positive cooperation in act or attitude pursuant to an exercise of free will”; the law also stipulates that intoxication impacts a person’s ability to consent. Turner was ultimately convicted of three felony counts of sexual assault (though he also received a lenient punishment largely thanks to inconsistent sentencing laws).

In contrast to California, however, Ohio does not define consent in its laws. In fact, an archaic legal loophole in its rape laws has garnered criticism in recent years. There, a woman can be drugged and sexually assaulted legally by her husband, as long he does not use force and they’re not technically separated. In other words, her ability to consent is stripped away because she’s married to her attacker.

“It’s pretty telling,” Murphy said, “that the critical thing most people look to to understand the nature of a sexual encounter – this idea of consent – is one that we don’t even have a consensus definition of in our society.”

That’s why the American Law Institute (ALI) began working several years ago to update the sex assault laws in its 1962 Model Penal Code, a text that offers model legislation often adopted by state legislatures. They started with coming up with a legal definition for consent, as it relates to criminal proceedings. Doing so, ALI Deputy Director Stephanie Middleton tells Broadly, gives a judge or jury a better idea of how to proceed in a trial.

“Under the old version of the model penal code,” she explains, “consent was, if a woman—I say woman because [the code] assumed it was a woman—didn’t physically resist, then it was viewed as she was consenting. That’s one of the reasons we had to go back there [to update].”

According to an ALI blog post, though, getting to an agreed-upon definition was “one of the most hotly debated issues in the project.” After looking at newer state statutes and various court opinions, institute members (comprised of judges, lawyers, and academics) ultimately agreed in 2016 that consent should be defined as “a person’s willingness to engage in a specific act of sexual penetration or sexual contact,” but that context and circumstances should also be considered.

Interestingly, the discussion did touch on the idea of affirmative consent, but some members raised concerns that society just wasn’t there yet. “A lot of our members thought it was just going too far and wasn’t practical to expect people to communicate to each other clearly a ‘yes’ or a ‘no’ as to each stage, whether it goes from kissing to necking to whatever,” Middleton says, “that that’s just not how people behave.” She adds that it’s a model that does appear to work on college campuses, though. (According to one researcher’s assessment, there was strong evidence that since the law was implemented for California students, sexual assault reporting rates on college campuses have increased.)

Because the project is ongoing, no states have yet adopted the ALI’s definition of consent, Middleton says. “We have a lot of work to do. We’re still grappling with some very difficult issues, but we really want to be sure that we don’t just stick with what [many] states currently have on the books.”

She adds: “There are some states that have old-fashioned views about consent.”

In fact, a lone state senator in North Carolina last year tried to take on a legal loophole that said a woman could not revoke consent during sex after initially giving it, even if her partner turns violent. For almost four decades, “no” has only legally meant “no” in the state if a person says so before engaging in sex. The North Carolina Supreme Court ruled in 1979 that if a woman consents to penetration then withdraws her consent, the accused can’t be found guilty of rape.

Amy Guy is a North Carolina woman who experienced the law firsthand. When her estranged husband showed up drunk to her home in 2016, WRAL reported, she agreed to have sex with him, but begged him to stop when he got violent. Because of that court ruling, the charges against him were lowered from second-degree rape to misdemeanor assault on a female; he received a 10-month jail sentence.

State Sen. Jeff Jackson—whose bill clarified that a person who continued having sex with someone after they withdrew consent did so against their will and could be charged as such—told Broadly last year he first encountered this loophole while working as a criminal prosecutor, when his office had to dismiss a rape charge because of similar circumstances. "Very few legislators are aware that this is the current state of our law," Jackson said at the time. "They're very surprised when I tell them.”