The University of the Michigan Law School and the Center on Wrongful Convictions at Northwestern University School of Law have produced a National Registry of Exonerations that claims to be “an up to date list of all known exonerations in the United States since 1989.”
Scott “Grits” Henson cautions that the 890 people who made the list constitute a representative sample. In Texas, for instance, Dallas County has contributed dozens of names to the list while not a single exoneration from Bexar County (San Antonio) appears. This says more about the due diligence of prosecutors in the respective counties than the proficiency of the criminal justice system.
Henson also points out that most successful exonerations take over a decade of tedious and often discouraging work and only those who fight long and hard are ever successful.
The registry lists only known exonerations because some exoneration stories get little or no attention. I was pleased to note, for instance, that the names of Ann Colomb and three of her sons appear on the registry. This was the first big case Friends of Justice tackled after the Tulia drug bust and, without our involvement, I fear the family would still be in prison or, if they were quietly exonerated, no one would have noticed. As it was, Radley Balko, then of Reason magazine, was the only reporter I could entice into covering this disturbing story. Alexandra Natapoff highlighted the Colomb story in her book on criminal informants and in some of her shorter pieces on the subject , but she only knew about the case because she heard me talk about it.
How many other cases like this are out there? The report doesn’t claim to be exhaustive. “No matter how tragic they are, even 2,000 exonerations over 23 years is a tiny number in a country with 2.3 million people in prisons and jails. If that were the extent of the problem we would be encouraged by these numbers. But it’s not. These cases merely point to a much larger number of tragedies that we do not know about.”
Henson’s research suggests that approximately 1.5% of criminal cases in Texas involve wrongful convictions. If so, 2,000 innocent people are currently behind bars in the Lone Star State.
Henson concludes that the registry of exonerations tells us much more about how defendants are wrongfully convicted than it says about how many have suffered this fate.
Friends of Justice 
Just a note about one Tulia exoneree: Some Tulians are fond of pointing at some of the exonerees who have gone back to prison since being exonerated. I have heard the claim that “they’re all back in prison now.” That claim is demonstrably false.
One exoneree is working at the Tulia nursing home. Patricia and I are there frequently visiting friends–friends who were very supportive of the Tulia Drug Bust and made statements like, “Lock ’em up on throw away the key.” This particular exoneree is one of their faithful attendants. She is loving and gentle, and they love her. It would not be possible for her to work there had she not been exonerated and the record expunged. How much better it is for all concerned that she has a job and is seeking further credentials to work in the health care field. I told her one day how glad I am that she is working there, and that I am glad for the part I had in making it possible. She teared up just a bit as she thanked me.