Nafissatou Diallo seems "vivid and compelling" when describing how (she says) Dominique Strauss-Kahn violently sexually assaulted her–though not when discussing her murky past, shady associates, $100,000 in bank deposits, and the like.

So says Newsweek, which interviewed her for a cover story. Many viewers of her TV appearances agree. So why shouldn’t she get her day in court?

She should–in civil court. But not in criminal court, in part because of her history of telling vivid and compelling lies, including her invention of a years-ago fictional gang rape and her false statements about her movements immediately after the alleged Strauss-Kahn assault. Plus the inherent implausibility of her claim that a man she had never met suddenly rushed in naked from the bathroom while she was cleaning his suite, attacked her like a madman, and forced her without a weapon to perform oral sex.

Diallo’s history of serial lying alone makes it clear that the prosecution could never prove Strauss-Kahn guilty of the violent sexual assault charged in the indictment beyond a reasonable doubt.

In short, Manhattan District Attorney Cyrus Vance Jr. should drop the case.

Remember the Duke lacrosse rape fraud? Remember Tawana Brawley?

Some seem to unlearn the lessons of such cases every time a poor (or not so poor) woman of color accuses a rich (or not so rich) white male of doing something horrible. Especially when the accused admits to conduct that was, at best, unseemly and crude.

The hard fact is that in a great many "he said, she said" cases–including this one–it is impossible to be confident of whether or not the woman consented.

The judgment underlying the criminal justice system’s reasonable-doubt rule is that–as terrible as it is for a victim (especially of a sex crime) to see a criminal escape punishment–it is far, far worse for an innocent person to be convicted of a crime.