"One in 25 criminal defendants who has been handed a death sentence in the United States has likely been erroneously convicted. That number—4.1% to be exact—comes from a new analysis of more than 3 decades of data on death sentences and death row exonerations across the United States.
“This was a very carefully done and carefully considered approach,” says statistician Bruce Levin of Columbia University, who was not involved in the new study. “The analysis was quite sophisticated, and the authors were transparent about both their assumptions and methods.”
...To calculate a more accurate false conviction rate, Samuel Gross, a law professor at the University of Michigan Law School in Ann Arbor and a former criminal defense lawyer, decided to focus on one small subset of criminal cases: those that result in death sentences.
“Every case where you have a death sentence is recorded in a national database,” Gross says. “And the rate at which errors are detected in death penalty cases is orders of magnitude higher than in other cases.” Defendants on death row have better access to attorneys, he notes, and more attention and resources are generally devoted to ensuring that their convictions are accurate........."
More Than 4% of Death Row Inmates May Be Innocent | Science/AAAS | News
Rate of false conviction of criminal defendants who are sentenced to death