What causes wrongful convictions? Lies, mistaken eyewitnesses top the list.

Researchers examined 873 wrongful convictions and found that perjury or false accusations were responsible for more than half. New report offers insight into what leads to miscarriages of justice.

False accusations, official misconduct, and mistaken eyewitness identity are the primary reasons behind hundreds of wrongful convictions nationwide over the past 23 years, legal researchers conclude in a new report.

The report, released Sunday, is part of a database compiled by the University of Michigan and Northwestern University law schools that for the first time tries to pinpoint the problem of flawed judicial outcomes in state and federal courts. 

Researchers identified 873 wrongful convictions between January 1989 and March 2012; 46 percent of the cases examined were homicides, 35 percent were sexual assaults, and the remainder were other crimes. Half involved African-Americans, 38 percent whites, and 11 percent Latinos. The report concluded that perjury or false accusations were responsible for just over half of the failures, followed by mistaken eyewitness identification, official misconduct, false or misleading evidence, or false confession.

The number is tiny compared with the hundreds of millions of criminal cases handled over the same period, says Samuel Gross, a University of Michigan law professor and lead author. The figure is based on formal decisions by courts or executive officers; the majority of the wrongful convictions were cleared without the use of DNA evidence.

“These are the ones we know about. They don’t give us any direct measure of how common false convictions are across the system,” Mr. Gross says. “They just give us a sense of the ones that have come to light.”

Stanley Fisher, a criminal law professor at Boston University who is not affiliated with the report, says the effort is part of a larger trend over the past two decades called the “Innocence Revolution.” Breakthroughs in the use of DNA evidence and greater awareness of past abuses had prompted reforms in police and court procedures, such as videotaping confessions from crime suspects, he says.

The trend has been fueled not only by DNA testing, but also by social science research that has questioned the reliability of long-standing police techniques such as how suspects in a crime are lined up against a wall and picked out by an eyewitness, or how photographs are shown to witnesses. It has affected how judges give instructions to juries, for example, when listening to testimony from an eyewitness to a crime.

“In earlier generations, I think we were a little more Pollyanish in our belief that the system of justice will bring these issues to light,” says Carol Steiker, a Harvard Law School professor who was also not involved in the report. “It’s not a new problem; we’re just newly aware of it.”

Still, the report is unlikely to dispel persistent questions about the integrity of the US criminal justice system. While violent and property crimes have dropped dramatically in the US since 1980, the national prison population has quadrupled and is now larger per capita than in any other country, with 2.3 million people in federal, state, and local prisons as of 2010, the most recently available figures from the federal Bureau of Justice Statistics. As well, African-American men make up a disproportionate number of the national prison population. Incidents like the Trayvon Martin shooting in Florida, and clear missteps by police investigators, have only added to perceptions that the criminal justice system is biased and partial.

Gross says the report’s findings shouldn’t be interpreted as an indication that the US system is completely broken; no criminal justice system anywhere will be perfect, he says.

“Are false convictions inevitable? Airline crashes, car crashes, unfortunate incidents on the operating table – these are all inevitable to a certain degree. The issue is: can we minimize them?” he says. “We will not have a system when false convictions will never occur. But we could have far fewer.

“My guess is people are less uneasy about the criminal justice system than they are about the banking system these days,” Gross says. “There is a serious problem here, but the problem is not that you need to start from scratch. What we need to do is pay closer attention.”

Skepticism about criminal procedures and demand for greater surety in its outcomes have affected attitudes toward the death penalty as well, say legal experts.

“Justice [Thurgood] Marshall, whom I clerked for, liked to say: ‘If you execute an innocent person, what are you going to say? Oops?’ ” Ms. Steiker says.