Basketball star Kobe Bryant (search), accused of sexually assaulting a 19-year-old hotel spa worker in Colorado, insists he didn't commit a crime because the sex was consensual. The young woman says otherwise.

Under Colorado law, Bryant's fate hinges on whether a jury concludes he used or threatened force upon his accuser — but the standard of guilt in rape cases isn't the same nationwide.

Illinois this year became the first to pass a "No Means No" law, specifying that consent can be withdrawn at any time during sexual activity. The new legislation aims to tackle the notorious "gray area" in sexual assault cases.

"If two people are having consensual sex (and) one of those partners withdraws their consent, it is the obligation of the other partner to stop," explained state Sen. Dan Rutherford (search), a Republican who co-sponsored the amendment. "No means no."

The legislation wasn't enacted because of the Bryant charges. Instead, it was a well-known California rape case that inspired the legislation in Illinois.

That case involved an alleged 2000 date rape that happened between a pair of teens at a party, according to Rutherford's Web site.

Initially, a California court found that the girl first agreed to sex but the boy wouldn't stop when she changed her mind. But appellate courts were mixed on whether no always means no in cases of consensual sex, according to the site. Ultimately the state Supreme Court stepped in to clarify that consent can be withdrawn at any time.

Rutherford said the California dispute — which lasted for three years — was the impetus for the Illinois legislature's decision to make its own sexual assault laws clearer, since they're similar to the California statute.

The clarification was also necessary, he said, because state courts have reached different interpretations of what defines consensual sex — leading to inconsistent rulings.

"Those that say, well, it was already understood or it didn't need to be there [were] wrong," he said.

But legal analysts stress that the updated law doesn't make it easier for prosecutors to win sexual assault convictions.

"The standard in any criminal case is proof beyond a reasonable doubt," said Fox News legal analyst Lis Wiehl. "So No Means No is one more tool, but it's still going to come down to a 'he said, she said' without any physical evidence or witnesses to corroborate the victim's testimony."

Many rape counselors believe the law will empower victims to come forward, because it lessens potential confusion about non-consensual sex.

"No means no — flat out," said rape crisis counselor Kelly Henry. "It doesn't matter what the situation, whether someone was drinking and went up to their room. No means no."

The clarified clause won't have a direct bearing on the Kobe Bryant trial, which will take place in Colorado. But legal analysts say it could have an indirect effect — inspiring other legislatures to follow in Illinois' footsteps, depending on the outcome of the Bryant case.

"The Illinois law will have no impact on the Kobe Bryant case," Wiehl said. "But it could have moral weight. I wouldn't be surprised if other states followed suit."

Fox News' Catherine Donaldson-Evans contributed to this report.