The report, "Irreversible Error," by the Constitution Project, found problems with the way the penalty is carried out in the U.S. and by the legal procedures that precede executions. Prepared by people on both sides of the issue, the report took no position on the use of the death penalty.
Last week, Clayton Lockett, a convicted killer in Oklahoma, died of a heart attack 10 minutes after prison officials decided to halt his execution. Another man who was scheduled to be put to death immediately after Lockett was granted a two-week stay.
The report found that much in the justice system from arrest through appeals increases the possibility that innocent people will be charged with capital crimes, convicted and even executed. A majority of police departments do not routinely videotape interrogations, increasing the chance of false confessions; public defenders are often underpaid and overworked; and prosecutors sometimes conceal evidence favorable to the defense with little penalty.
The panel said the system is also biased against racial minorities, and states have too much leeway in deciding which convicts are too mentally ill or disabled to be executed.
The report found that three-drug protocols like the one used in Lockett's execution are often faulty. In some cases, the panel said, prisoners are not given enough anaesthetic as the first drug.
The experts said a large dose of anesthetic -- the method used in most cases to put down animals in the U.S. -- would be surer. But companies supplying anesthetics might not be willing to do so for executions.