Check out the National Registry of Exonerations. This database, which is jointly sponsored by the University of Michigan and Northwestern schools of law, attempts to keep track of all exonerations nationwide. The Registry records every exoneration since 1989 and can be sorted by geographic area as well as by cause(s) of wrongful convictions, such as mistaken witness identification, false confession, junk science, ineffective assistance of defense counsel, etc.
The authors of the National Registry of Exonerations recognize that society has a moral obligation that goes beyond freeing those who were wrongfully convicted. We also have an obligation to try to analyze the flaws in the system that led to the conviction of innocent people in the first place. Unless we understand history, we’re doomed to repeat it.