Did you know that since 1989 more than 2,000 inmates in the U.S. have been wrongfully accused of crimes and subsequently exonerated for the mistake? That's about 87 people per year.

The startling data comes from a new project put together by the University of Michigan Law School and Northwestern University, as the institutions compiled criminal cases over the past 23 years (1989 is when DNA evidence became a widely-employed tactic) to come up with the National Registry of Exonerations. Most of the cases were serious crimes -- including drug crimes, sex crimes and violent offenses.

In addition to the variety of cases, there were myriad reasons for why the cases were eventually overturned. Recanting or unreliable witnesses and police corruption were prominent reasons for exoneration; but false confessions were possibly the most eye-opening reason for some of the wrongful convictions.

"Nobody had an inkling of the serious problem of false confessions until we had this data," said one Northwestern official.

The National Registry of Exonerations shows that, while those who are innocent can still wrongfully be found guilty, the role of criminal defense is extremely important in our justice system. New evidence or a change in the circumstances of an alleged crime can lead to the exoneration of a defendant, even if it is long after a conviction.

The new database is also being called "the tip of the iceberg" by a University of Michigan Law School official who believes there are many more exonerations that are not yet known. Cook County (where Chicago is located) and Dallas County reported 78 and 36 exonerations, respectively, while major counties in California (with more than 1 million people in them) reported no exonerations.

This is a byproduct of the fact that only 900 total cases were meticulously reviewed, so there could be many more defendants with a legitimate claim to innocence.

Source: Los Angeles Times, "Registry tallies over 2,000 wrongful convictions since 1989," David G. Savage, May 20, 2012