US death row study: 4 percent of defendants sentenced to die are innocent

At least 4.1% of all defendants sentenced to death in the US in the modern era are innocent, according to the first major study to attempt to calculate how often states get it wrong in their wielding of the ultimate punishment.

A team of legal experts and statisticians from Michigan and Pennsylvania used the latest statistical techniques to produce a peer-reviewed estimate of the “dark figure” that lies behind the death penalty – how many of the more than 8,000 men and women who have been put on death row since the 1970s were falsely convicted. …

The study concludes that were all innocent people who were given death sentences to be cleared of their offences, the exoneration rate would rise from the actual rate of those released – 1.6% – to at least 4.1%. That is equivalent in the time frame of the study, 1973 to 2004, of about 340 prisoners – a much larger group than the 138 who were exonerated in the same period.