The Supreme Court has not banned capital punishment, as it should, but it has long held that the death penalty is unconstitutional if randomly imposed on a handful of people. An important new study based on capital cases in Connecticut provides powerful evidence that death sentences are haphazardly meted out, with virtually no connection to the heinousness of the crime.

A number of studies in the last three decades have shown that black defendants are more likely to be sentenced to death if their victim is white rather than black. But defenders of capital punishment often respond to those studies by arguing that the “worst of the worst” are sentenced to death because their crimes are the most egregious.

The Connecticut study, conducted by John Donohue, a Stanford law professor, completely dispels this erroneous reasoning. It analyzed all murder cases in Connecticut over a 34-year period and found that inmates on death row are indistinguishable from equally violent offenders who escape that penalty. It shows that the process in Connecticut — similar to those in other death-penalty states — is utterly arbitrary and discriminatory.

From 1973, when Connecticut passed a death penalty law, to 2007, 4,686 murders were committed in the state. Of those, 205 were death-eligible cases (capital murders that include the killing of a police officer, murder for hire, murder-rape and murder committed during a kidnapping) that resulted in some kind of conviction, either through a plea bargain or conviction at trial. The arbitrariness started at the charging level: nearly a third of these death-eligible cases were not charged as capital offenses as they could have been, but as lesser crimes. Sixty-six defendants were convicted of capital murder, 29 went to a hearing for a death sentence, nine death sentences were sustained and one person was executed.