Police misconduct, such as falsifying evidence, is a leading cause of wrongful convictions, study finds

WASHINGTON – Actions by police officers, including witness tampering, violent interrogations and falsifying evidence, account for the majority of the misconduct that lead to wrongful convictions, according to a study released Tuesday by the National Registry of Exonerations that focused on the role police and prosecutors play in false convictions in the U.S.

Researchers studied 2,400 convictions of defendants who were later found innocent over a 30-year period and found that 35% of these cases involved some type of misconduct by police. More than half – 54% – involved misconduct by police or prosecutors. 

The findings by the National Registry of Exonerations, a project that collects data on wrongful convictions, come as protests over racial injustice and police brutality spread across many cities for several months following the May 25 death of George Floyd in police custody. 

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Misconduct that leads to wrongful convictions rarely comes to light and doesn't usually lead to mass protests and a racial reckoning, although they involve the same reliance on secrecy and deception, said Samuel Gross, a University of Michigan law professor and one of the authors of the study. 

"The basic underlying truth is if you're innocent of a crime and you were convicted of it, the chances of it ever coming to light are, first, not great and, second, get worse and worse the less serious a crime it is," Gross said. "If you're convicted of a misdemeanor and you're innocent of it ... the chance of anybody caring is very low."

But, Gross said, "We're not talking about all police officers or most police officers. What's disturbing is it happens at all and it happens with some regularity."

Researchers found that misconduct by police and prosecutors is among the leading causes of disproportionate false conviction of Black defendants. For example, 78% of Black defendants who were wrongly accused of murder were convicted because of some type of misconduct. That number is 64% for white defendants, according to the study. An even wider gap: 87% of Black defendants later found innocent who were sentenced to death were victims of official misconduct vs. 68% for white defendants.

As of Monday, the National Registry of Exonerations had nearly 2,670 people who have been exonerated since 1989, and the list grows regularly.

Hiding evidence

The study found that hiding evidence that is favorable to defendants is the most common type of misconduct.

Researchers cite five murder trials in which prosecutors concealed evidence about the cause of death. In one case, a woman was convicted of killing her boyfriend, but prosecutors did not disclose a medical report that found he had died of suicide.

"In a few rape exonerations, the authorities concealed evidence that the complainants had a history of making false rape allegations," according to the study. "And in at least a dozen child sex abuse cases, police, prosecutors and child welfare workers concealed statements by the supposed victims that they had not in fact been molested."

In some cases, police officers falsely claimed they were victims of assaults by defendants. In one such case, police officers from Chattanooga, Tennessee, beat a defendant at a reentry facility because he defended himself. Adam Tatum was sentenced to two years in prison for assaulting officers but was later exonerated after video showed that officers attacked him without provocation. Tatum sued and later settled for $125,000.

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Consequences are rare

Police officers were disciplined or convicted of crimes in only 19% of exonerations that involved some type of misconduct, according to the study. That's a rate five times higher than those for prosecutors, whose misconduct account for 30% of the cases. 

Perhaps most infamous is former Chicago Police Commander Jon Burge who was convicted of perjury for lying about his role as the leader of a group of officers who tortured suspects into confessing. 

Still, reforms have happened in recent years.

Violent interrogations have become less common in the past 15 to 20 years as more states began requiring police departments to record interrogations. 

In 2013, the Justice Department and the International Association of Chiefs of Police called for investigative reforms meant to prevent wrongful convictions, including new guidelines on recording police interviews and greater scrutiny of eyewitness identifications.