Today the U.S. Supreme Court upheld lethal injection, the execution method used by nearly every state with capital punishment, against a challenge by two Kentucky murderers who argued that it violates the Eighth Amendment. Seven justices agreed that the three-chemical lethal injection method, which involves a barbiturate for anesthesia, pancuronium bromide to paralyze the muscles, and sodium potassium chloride to stop the heart, is not "cruel and unusual punishment." But they disagreed about the proper standard to apply in reaching that conclusion.
The plurality opinion by Chief Justice John Roberts, which was joined by Justices Anthony Kennedy and Samuel Alito, says Kentucky's execution method passes muster because it does not pose a "substantial risk of serious harm": Although it's true that a condemned man will experience suffocation and pain if he is not given an adequate dose of the anesthetic, the odds of such a mistake seem to be pretty low. In a concurring opinion, Justice Stephen Breyer says there is not enough evidence to conclude that the three-drug method poses even "a significant risk of unnecessary suffering," a more easily satisfied test for cruel and unusual punishment. While expressing reservations about the use of pancuronium bromide (which, among other things, prevents the prisoner from signaling his discomfort if he does not get enough of the barbiturate) and about the death penalty generally, Justice John Paul Stevens agrees that there isn't enough evidence on the record to overturn the procedure. Justices Antonin Scalia and Clarence Thomas say an execution method violates the Eighth Amendment "only if it is deliberately designed to inflict pain." The two dissenters were Justices Ruth Bader Ginsburg and David Souter, who favored remanding the case for consideration of whether Kentucky's failure to adopt safeguards used by other states to make sure the prisoner is unconscious "poses an untoward, readily avoidable risk of inflicting severe and unnecessary pain."
Here is my last comment on the subject, which includes links to earlier reason coverage.