What does innocence have to do with cruel and unusual punishment?

A new body of fact must be accounted for in deciding what, in practical terms, the Eighth Amendment guarantees should tolerate.-Justice David Souter, dissenting in Kansas v. Marsh INTRODUCTION As a question of constitutional interpretation, should the risk of executing the innocent matter in evaluating whether the death penalty is a “cruel and unusual punishment” under the Eighth Amendment? Since 1989, there have been one hundred and sixteen individuals exonerated from death row, including twenty-five prisoners freed through post-conviction DNA testing. More than half of these exonerations have occurred in the last fifteen years. A study by the National Academy of Sciences found that since 1973 one in twenty-five sentences involved the conviction of an innocent person. A number of these exonerees spent decades on death row before exoneration, some coming within weeks or even days of execution. Even more worrisome, there is a growing list of individuals who have been executed despite strong claims of innocence: Cameron Todd Willingham, Carlos DeLuna, Troy Davis, and Lester Bower. In 2004, Texas executed Cameron Todd Willingham for the murder of his three young children based on the testimony of a fire investigator who concluded that someone used an accelerant to start the fire. Two nationally renowned arson experts would later denounce this testimony. One of them concluded that there was “nothing to suggest to any reasonable arson investigator that this was an arson fire,” and the other determined that the arson finding was not grounded “in modern fire science” and “could not be sustained.” Carlos DeLuna was executed in 1989 for a murder in Corpus Christi, Texas. The Columbia University Law School Human Rights Law Review dedicated an entire issue to the case, detailing how DeLuna was executed for a crime committed by Carlos Hernandez. DeLuna’s conviction hinged upon a single eyewitness identification that occurred while he was sitting in a police car at the crime scene - despite both a total lack of forensic evidence against him and forensic evidence implicating the real killer, Hernandez. In 2011, Georgia executed Troy Anthony Davis for the murder of a police officer in a case in which seven of the nine trial witnesses recanted their testimony, no physical evidence tied Davis to the crime, and multiple people said that Sylvester “Redd” Coles, one of the two witnesses remaining, confessed to - and even boasted about - killing the officer.