What happens when the police lie? 

Most Americans understand that the police are allowed to lie to suspects. Whether learned from watching procedurals, news reports or personal experience, it is generally recognized that deceit during suspect interrogations is a routine feature of American policing.  

What is less understood are the consequences of accepting such practices, and the extent to which the U.S. stands as an outlier in sanctioning them.  

To elicit confessions, police routinely employ a variety of manipulative practices, including lying about the existence of incriminating evidence or falsely implying leniency in exchange for cooperation. These techniques are not tools of a last resort, but core components of interrogation in the U.S. They are taught in some of the most influential police manuals, tolerated by judges and widely accepted as standard practice. 

Defenders of these practices are quick to point out that police have tough cases on their hands and must use all methods at their disposal to find the truth. Undoubtedly, deception is an effective technique at times for eliciting confessions from criminals and solving crimes in some cases.  

Yet these techniques also have costs. Despite potential investigative advantages, the prevalence of deception has had severe social consequences, not only for the innocent people subjected to such practices, but also for the integrity of the criminal justice system. 

First, the use of deceptive interrogation techniques significantly increases the risk of false confessions. The psychological pressure and manipulation inherent in deceptive interrogation tactics can induce even an innocent suspect to admit to a crime. When faced with repeated assertions that incontrovertible evidence exists to secure a conviction — say a DNA test — some suspects begin to doubt their own recollections. Others make a calculated decision that the officers’ minds are made up and confessing is in their best interest.

One study of police detectives estimated that roughly 1 in 20 innocent suspects provides a false confession during interrogation — a staggering number, considering how many interrogations that occur daily.

Unfortunately, once elicited, false confessions are difficult to overcome in court, even in the face of contradictory evidence. As a result, false confessions routinely result in convictions, and indeed, are one of the leading causes of wrongful convictions in the United States. Of the hundreds of wrongful convictions overturned by the Innocence Project, 29 percent involved false confessions. For capital cases, that figure is 61 percent.

The problems with deception extend far beyond the interrogation room. The acceptability of lying to suspects appears to encourage a culture of deception that bleeds over into other aspects of police work where lying is illegal. Numerous studies have documented the widespread nature of police perjury in the United States.

Officers have been known to fabricate consent to searches, invent probable cause, create fictional confidential informants, misrepresent whether Miranda rights were read, or lie about the location of arrests to circumvent Fourth Amendment protections. This type of lying is so commonplace that some officers have invented a name for it: "testilying."  

Ultimately, as lying is normalized as an acceptable investigative tool, and officers learn to hone their skills, it fosters a mindset that deception is justified more broadly in the pursuit of justice. This rationale then carries over into other contexts. An officer who is trained to lie to a suspect to get a confession may use the same logic in tweaking the facts on the witness stand to secure a conviction. Since these impermissible lies are rarely identified or punished, officers learn that they can lie with impunity. 

In the long run, the pervasiveness of police deception — both investigative and testimonial — undermines the legitimacy of our criminal justice system. The discovery that officers frequently lie, for many, leads to a broader disillusionment with law enforcement. This erosion of trust in turn reduces cooperation with police, as citizens become less likely to report crimes or assist in investigations. 

While proponents argue that restricting deception would impede investigations, evidence from peer nations suggests otherwise. The U.S. stands out from other developed democracies in allowing deceptive interrogation techniques. Most developed democracies — including England, France, Germany and Japan — prohibit or heavily restrict police deception during interrogations, with no apparent effect on clearance rates. Indeed, when the U.K. implemented reforms to curb deceptive tactics, studies found no corresponding drop in confession or conviction rates. 

Policymakers should question the outsized role deception plays in criminal investigations and consider policies to limit its pervasiveness. This need not require an outright ban on the use of deception in interrogations. Rather, more moderate reforms could prove effective as well such as prohibiting the most coercive techniques, allowing deception only as a last resort, or limiting the use of deception to the most serious crimes.  

An effective criminal justice system requires the prioritization of truth and protection of the innocent, just as much as it demands the identification and conviction of the guilty. 

Andrew Eichen is the author of “Broken Trust: The Pervasive Role of Deceit in American Policing” for the Cato Institute and a McCourt Scholar, Georgetown’s McCourt School of Public Policy.