ANN ARBOR—Exonerations of defendants convicted of serious crimes more than tripled over the past 15 years as DNA and other new evidence overturned the convictions, a University of Michigan study shows.

The study, “Exonerations in the United States, 1989 through 2003,” includes what is believed to be the most comprehensive listing of exonerations in the United States to date and was conducted by U-M law professor Samuel Gross and four students. The study reports that since 1989—when the first DNA exoneration occurred—328 defendants have been exonerated in the U.S. after being convicted of serious crimes such as rape and murder.

The exonerated were 316 men and 12 women; 145 of them were cleared by DNA identification technology, and 183 by other sorts of evidence. Exonerations increased sharply from about 12 a year through the early 1990s to an average of 43 annually after 2000, the U-M study found. The study did not include at least 135 additional innocent defendants who were framed by rogue police officers and cleared within the last five years in two mass exonerations in California and Texas.

“The most important findings of our study concern the cases that we don’t see—miscarriages of justice that are not detected,” said Gross, an expert on criminal procedure and capital punishment. “The exonerations we see are just the tip of an iceberg.   It is clear that there are many more false convictions that are never discovered.”

The research indicates that the justice system must continue to improve its investigative methods to reduce the number of convictions of innocent people. The study focuses on three common causes of false convictions: misidentifications, false confessions and perjury. According to Gross, the police should implement different tactics to reduce the danger of false convictions based on different types of faulty information. For instance, convictions based on false confessions could be greatly reduced by videotaping police interrogations so that judges and juries can see for themselves the circumstances that led the defendant to confess.

Another key finding in the research involved racial disparities in the juvenile justice system. Ninety percent of exonerated juvenile defendants are African-American or Hispanic.

The U-M students participating in the research were Kristen Jacoby and Daniel Matheson, Law School; Nicholas Montgomery, Department of Economics and Ford School of Public Policy; and Sujata Patel, School of Public Health.

Related Links:

• Gross
• Read the report 
• Death Penalty Information Center