In fact, the prevailing failure to try to convict rapists is directly related to the way police and prosecutors treat victims, their testimony and the evidence. It is telling that the media description of the alleged victim in the Strauss-Kahn case highlights her religious devotion and life struggles — factors that in many people’s eyes would make her a more credible witness. But victims without those attributes are often perceived very differently. Police officers sometimes abandon a rape case because, based on initial interviews and context alone, they don’t believe the alleged victim is a credible witness.

Research suggests that 3% to 8% of rape complaints are false — similar to the proportion of other crime complaints. But researchers have found that police officers are much more likely to mistrust an alleged rape victim than they are to mistrust other victims, particularly if the woman alleging sexual assault doesn’t conform to police notions of how a woman should act.

This course of action may seem logical: Few would want the police to waste valuable resources on investigations of crimes that didn’t really happen. However, experience from jurisdictions such as New York — where all rape kits, as the physical evidence is called, are processed — reveals that a subjective analysis of victim credibility can be wrong. After New York decided to test every rape kit, and not just the ones from cases in which the police officer subjectively felt the allegation was likely to be true, the arrest rate rose over five years from 40% to 70% of complaints filed, and the proportion of convictions grew too.