death penalty innocence

New Study Suggests Over 4% of People Sentenced to Death are Likely Innocent

According to new peer-reviewed research published in one of the most authoritative scientific journals in the world – Proceedings of the National Academy of Sciences – over four percent of all those sentenced to death in the United States from 1973 through 2004 were innocent. The percentage of innocent people sentenced to death (4.1%) is more than double the percentage of those actually exonerated and freed from death row during the study period (1.6%).

For the study, The Rate of False Conviction of Criminal Defendants Who are Sentenced to Death, a team of statisticians and legal experts conducted a rigorous statistical analysis of all death sentences from 1973 to 2004. The researchers noted that defendants who are sentenced to death have an extraordinarily high rate of exoneration as long as they remain on death row, under threat of execution. But most capital defendants are eventually taken off death row and resentenced to life in prison. Once that happens, the chances of being exonerated drop by almost 90%.

Read coverage of the study from the Associated Press.

Using survival analysis, a statistical technique common in medical studies, the researchers calculated the proportion of innocent defendants who would have been exonerated if all those sentenced to death remained on death row indefinitely – 4.1%. They conclude that this is “a conservative estimate of the proportion of false conviction among death sentences in the United States.”

This means that the criminal justice system is missing a disturbing number of innocent people who were sentenced to death. While most of these defendants were resentenced to life in prison (where they are likely to languish in anonymity), the study concludes that: “[I]t is all but certain that several of the 1,320 defendants executed since 1977 were innocent.”

If we apply this statistical technique to Texas, it suggests that at least 11 of the state’s current 272 death row inmates are innocent.  Twelve individuals have been exonerated and released from death row in Texas due to evidence of their wrongful conviction.

Behind the numbers, of course, are real human beings:

  • Glenn Ford, the most recent death row exoneree, spent 30 years on Louisiana’s death row for a crime he didn’t commit; he was defended by inept lawyers with no criminal trial experience.
  • In April, the Texas Board of Pardons and Paroles denied a request for a posthumous pardon for Cameron Todd Willingham, despite strong evidence of his innocence of the crime for which he was executed in 2004.  Serious doubts remain as to whether the fire that took the lives of his three young daughters was caused by arson.  In addition, new evidence uncovered by the Innocence Project strongly suggests that jailhouse informant Johnny Webb received a deal from Navarro County District Attorney John Jackson in exchange for his testimony against Willingham at trial.
  • Carlos DeLuna was executed in 1989 for the murder of Wanda Lopez in Corpus Christi despite the fact that there was no physical evidence connecting him to the crime.  His court-appointed attorneys – one of whom had never tried a criminal case in court, let alone a capital murder case – failed to present any witnesses or mitigating evidence during the sentencing phase.  A groundbreaking investigation by the Columbia University Human Rights Law Review in May 2012 provides compelling evidence of the identity of the real killer – Carlos Hernandez – a violent and dangerous man who was well-known to law enforcement yet was ridiculed by prosecutors as a “phantom” of DeLuna’s imagination during his trial.


According to the new study, there are over 200 men and women with similar stories, but we don’t know their names. That is the tragic cost of continuing to rely on an error prone system in which one out of every 25 death sentences is imposed on an innocent person.