GEOFF BENNETT: The lack of legal clarity around consent laws in the U.S. means that many sexual assaults, especially ones on college campuses and involving alcohol, are not legally crimes.

But Texas lawmakers recently passed legislation to change that.

And the new law is set to take effect in September.

Producer Courtney Norris has our look at the bipartisan bill and the woman it's named after.

COURTNEY NORRIS: Ten years ago, Summer Willis attended a press conference in the U.S. for a fraternity party at the University of Texas at Austin, where she says she was drugged by one man and raped by another.

At the time, Willis was a college sophomore and did not report it.

She would later learn a loophole in the state's consent law meant what happened to her wasn't even considered sexual assault.

SUMMER WILLIS, Sexual Assault Survivor: The loophole my rape fell under was because I voluntarily accepted a drink from one person and another person raped me.

It doesn't count, one, because I voluntarily took a drink and two, because that person, when I entered the party, did not have the intent to rape me, even though someone else did.

COURTNEY NORRIS: In the U.S., there is no national legal definition of consent.

State laws determining the age of consent and what constitutes lack of consent differ.

And how a state defines consent plays a key role in whether an act is legally a crime.

SUMMER WILLIS: I think something cracked inside of me, realizing that, even if I wanted to, even if I went to the police the next day, they would have just turned me around.

COURTNEY NORRIS: Two years ago, Willis decided to speak up and push for legislative reform in Texas.

SUMMER WILLIS: If we have been drugged and made too incapacitated to say no, it doesn't count.

COURTNEY NORRIS: Since telling her story, Willis participated in more than two dozen marathons across the country to raise awareness for sexual assault, one with a mattress on her back and one on her hands and knees to symbolize the struggle of survivors.

Willis' advocacy got the attention of Texas lawmakers.

The Summer Willis Act clarifies, among other things, that sexual assault is without consent if the actor knows or reasonably should know that the other person cannot consent because of intoxication or impairment by any substance.

SUMMER WILLIS: If someone now knows you're intoxicated, that means no.

And I think that will be huge, especially on college campuses.

And I get chills knowing that we're protecting these people.

COURTNEY NORRIS: According to RAINN, a nonprofit that supports survivors of sexual violence, 13 percent of graduate and undergraduate students experience rape or sexual assault in the U.S. STATE SEN. ANGELA PAXTON (R-TX): She didn't want to be here for why she is here, but she has taken tragedy and turned it into triumph.

COURTNEY NORRIS: Willis says her story is just one example of how loopholes can allow sex to be considered consensual, despite consent not being given.

She hopes more states move to update consent laws.

SUMMER WILLIS: The easiest way to describe this bill, the Summer Willis Act, is that it defines consent, but there's a lot of other things that happen when you don't define consent.

And there are 20 states right now that still don't have those definitions.

COURTNEY NORRIS: For the "PBS News Hour," I'm Courtney Norris.