On January 6, the California Supreme Court ruled that when a woman rescinds consent during sex, the man becomes guilty of rape if he does not stop immediately.

Last month, Illinois became the first state to enact that principle into law. Such measures trivialize the crime of rape and encourage false accusations that, in turn, threaten the credibility of actual rape victims.

The new law reads, "(c) A person who initially consents to sexual penetration or sexual conduct is not deemed to have consented to any sexual penetration or sexual conduct that occurs after he or she withdraws consent during the course of that sexual penetration or sexual conduct."

A woman has a right to change her mind about sex at any point in the act. And, once that change has been clearly communicated, the man should cease sexual contact.

The situation is similar to inviting a guest into your home. If you unmistakably rescind the invitation, the "guest" should stay no longer than it reasonably takes for him to understand he is no longer welcome. And yet, if the invited guest chooses to remain, the offense he commits is trespass, not breaking and entering or burglary. Equally, a man who doesn't use force during invited sex but ignores signals is not committing rape but some other, lesser offense.

The Illinois law trivializes rape by placing a woman changing her mind on the same level as a woman who is brutally beaten into sexual submission. It places a man who may be confused by jumbled signals on the same level as one who holds a knife to a woman's throat in a dark alley.

As such, the law is an insult to every woman who has been forcibly raped. It is a threat to every man who becomes momentarily lost in the sex act or totally misreads a woman's response.

The "withdrawal of consent" standard also encourages false accusations by making the charge hinge entirely upon a "he said/she said" scenario.

Indications of consent are often public or provable: for example, an ongoing romantic relationship or having gone up to a man's hotel room at night. This means third parties are able to evaluate evidence that is independent of an accuser's truthfulness or her understanding of what happened. By contrast, indications of withdrawn consent are rarely public or provable.

Evidence that a sex act occurred proves nothing because most sex is consensual. It would make little sense to ask mugging victims if they had agreed to be beaten and robbed in the street because the automatic and overwhelming presumption is that they did not. But it makes perfect sense to ask alleged victims of rape whether they agreed to sex because that crime is defined not by the presence of an act but the presence of consent.

Nor is reporting distress to third parties real evidence because there is no way to verify the cause of the upset. The woman might well be traumatized because she withdrew her consent only to be ignored by the man. But she might also be overcome with shame or be infuriated by the man's dismissive attitude after sex.

Why would the woman lie? The answer: for the same reasons other human beings lie. For revenge, for profit, for attention, out of shame, out of panic ... The motives become more complicated in highly emotional situations. And when a misunderstanding is present, lies are not even necessary for stories to conflict.

In such a conflict, the accused is currently at a disadvantage in at least two ways. First, the presumption of innocence is reversed. Instead of being innocent until proven guilty, the accused has to present an affirmative defense that proves the sex was consensual. Second, the definition and standards of consent have been expanded to such a degree that it is a difficult claim to prove.

The issue of "withdrawn consent" will continue to play out in the spotlight due to the upcoming trial of Kobe Bryant. For weeks to come, reporters and commentators will speculate on exactly how much sexual contact the woman had agreed to with Kobe, on how clearly she stated her disagreements. The state of Colorado has no law that equates withdrawn consent with rape so the court's verdict may not hinge upon such questions. But the public's will.

I find myself in the strange position of believing Bryant to be innocent while hoping he is guilty. An "innocent" verdict would harden the belief that women lie about rape and it is men who are victimized. If this belief becomes widespread, it will harm not only women who are raped but also women who report any violence at the hands of a man.

Rape must not be trivialized; it should remain the violent act of taking sex through force or threat of force. Sexual contact that begins with consent and ends as unwelcome is simply in a different category than rape. If a new legal category or theory is required to address the situation of withdrawn consent, then it should be created. But the brutal crime of rape should not be diluted in the process.

Wendy McElroy is the editor of ifeminists.com and a research fellow for The Independent Institute in Oakland, Calif. Her new book is Liberty for Women: Freedom and Feminism in the 21st Century.  Reprinted with permission of ifeminists.com.