THOUSANDS of people plead guilty to crimes every year in the United States because they know that the odds of a jury’s believing their word over a police officer’s are slim to none. As a juror, whom are you likely to believe: the alleged criminal in an orange jumpsuit or two well-groomed police officers in uniforms who just swore to God they’re telling the truth, the whole truth and nothing but? As one of my colleagues recently put it, “Everyone knows you have to be crazy to accuse the police of lying.”

But are police officers necessarily more trustworthy than alleged criminals? I think not. Not just because the police have a special inclination toward confabulation, but because, disturbingly, they have an incentive to lie. In this era of mass incarceration, the police shouldn’t be trusted any more than any other witness, perhaps less so.

That may sound harsh, but numerous law enforcement officials have put the matter more bluntly. Peter Keane, a former San Francisco Police commissioner, wrote an article in The San Francisco Chronicle decrying a police culture that treats lying as the norm: “Police officer perjury in court to justify illegal dope searches is commonplace. One of the dirty little not-so-secret secrets of the criminal justice system is undercover narcotics officers intentionally lying under oath. It is a perversion of the American justice system that strikes directly at the rule of law. Yet it is the routine way of doing business in courtrooms everywhere in America.”

The New York City Police Department is not exempt from this critique. In 2011, hundreds of drug cases were dismissed after several police officers were accused of mishandling evidence. That year, Justice Gustin L. Reichbach of the State Supreme Court in Brooklyn condemned a widespread culture of lying and corruption in the department’s drug enforcement units. “I thought I was not naïve,” he said when announcing a guilty verdict involving a police detective who had planted crack cocaine on a pair of suspects. “But even this court was shocked, not only by the seeming pervasive scope of misconduct but even more distressingly by the seeming casualness by which such conduct is employed.”