Russell Bucklew, a Missouri death row inmate, in February 2014. (Associated Press)

Declaring that the Constitution “does not guarantee a prisoner a painless death,” a five-justice Supreme Court majority ruled last Monday that Russell Bucklew, a Missouri death-row inmate, can be executed by lethal injection. In so doing, the court raised the disturbing prospect that the state could legally inflict severe pain in the process of executing a prisoner.

Mr. Bucklew did not argue that lethal injection was always cruel and unusual under the Eighth Amendment, as some have argued in previous death penalty cases. Instead, he claimed that a rare medical condition made it unusually risky in his circumstance. Mr. Bucklew has cavernous hemangioma, a disease in which tumors filled with blood vessels grow in one’s head, neck and throat. “He claims that once the sedative pentobarbital is injected he will ‘lose the ability to manage’ the tumors in his airway and, as a result, will experience a ‘sense of suffocation’ for some period of time before the State’s sedative renders him fully unconscious,” Justice Neil M. Gorsuch, writing for the court, noted. Mr. Bucklew cited testimony from an anesthesiologist who raised the possibility that a tumor on his uvula would burst, causing his airway to fill with blood.

Factual questions are still unresolved about how much risk Mr. Bucklew faces and how much better alternative methods of execution might be for someone with his condition, and much of the majority opinion, as well as Justice Stephen G. Breyer’s dissent, dwell on these matters. If Mr. Bucklew is asking for a special exception from lethal injection, the courts ought to determine how special his case really is. The justices should have at the least demanded that much, ordering a trial during which more information could have been presented to a judge.

Yet the court ordered no such thing. Instead, the majority said Mr. Bucklew failed to present enough evidence that injecting him with a lethal dose of pentobarbital would cause prolonged and severe suffering and, crucially, that another method of execution would have been less risky for him.

Mr. Bucklew had suggested to the court that he could be executed using nitrogen asphyxiation, a process in which the inmate inhales nitrogen gas until he develops hypoxia, slips into unconsciousness and, later, dies. His lawyers cited research from other states showing that the “onset of hypoxia is typically so subtle that it is unnoticeable to the subject,” causing unconsciousness in a mere 17 to 20 seconds. Yet the court rejected Mr. Bucklew’s proposed alternative. No other state has yet used it. The justices complained that Mr. Bucklew did not provide answers “on essential questions like how nitrogen gas should be administered (using a gas chamber, a tent, a hood, a mask, or some other delivery device); in what concentration (pure nitrogen or some mixture of gases); how quickly and for how long it should be introduced; or how the State might ensure the safety of the execution team, including protecting them against the risk of gas leaks.”

If executing a particular inmate in a particular way would cause him severe pain, should it matter that he has not provided the state, chapter and verse, a finely detailed alternative execution method? Should the state not bear more responsibility to find a more humane procedure? The court has spoken, but its rigid, tight view of the Eighth Amendment leaves too little room for prisoners to claim they will suffer too much at the hands of the government.