Posted Apr 29, 2014 12:41 pm CDT
A statistical study concludes that about one in 25 people who are sentenced to death are likely innocent.
The study says only 1.6 percent of those on death-row are exonerated and released, but the actual figure is likely a minimum of 4.1 percent when statistical assumptions are applied to the cases of people who are removed from death row and given life sentences. The study says cases of those removed from death row no longer get the rigorous scrutiny of capital cases, and there would be an increased rate of exonerations if they had remained capital cases.
Death sentences represent less than one-tenth of 1 percent of prison sentences in the United States, but they accounted for about 12 percent of known exonerations of innocent defendants from 1989 to 2012, the study says.
The Associated Press and a press release by the Death Penalty Information Center have news of the study, published in the Proceedings of the National Academy of Sciences. The study’s lead author is University of Michigan law professor Samuel Gross.
“Since 1973, nearly 8,500 defendants have been sentenced to death in the United States, and 138 of them have been exonerated,” Gross said in the press release. “Our study means that more than 200 additional innocent defendants have been sentenced to death in that period. Most of these undiscovered innocent capital defendants have been resentenced to life in prison, and then forgotten.”
AP spoke with statistics experts for their take on the findings. Yale University biostatistics expert Theodore Holford said the study “seems to be a reasonable way to look at these data.” University of South Carolina statistics professor John Grego said it might be better to take the study’s margin of error into account, which would mean the innocence rate is probably between 2.8 percent and 5.2 percent.
The study refutes a statement made by Justice Antonin Scalia in a concurring opinion in 2007. He wrote that American criminal convictions have an error rate of 0.027 percent “or, to put it another way, a success rate of 99.973 percent.”
The study says Scalia’s statement “would be comforting, if true. In fact, the claim is silly. Scalia’s ratio is derived by taking the number of known exonerations at the time, which were limited almost entirely to a small subset of murder and rape cases, using it as a measure of all false convictions (known and unknown), and dividing it by the number of all felony convictions for all crimes, from drug possession and burglary to car theft and income tax evasion.”