(James A. Finley/AP Photo)

Without explanation, the Supreme Court halted the planned execution late Wednesday of a death row inmate in Missouri who claims that if he is executed using the state's lethal injection protocol he could suffer a tortuous death due to his rare medical condition.

It is unusual that the court issues such a stay, and the brief order indicated no noted dissents. The order simply said that the stay for Russell Bucklew was granted pending appeal in the U.S. Court of Appeals for the Eighth Circuit.

"What this means," Cheryl Pilate, a lawyer for Bucklew, said in a statement , "is that the appeals court will hear Mr. Bucklew's claims under the Eighth Amendment that he faced a great likelihood of a prolonged and tortuous execution because of the unique and severe medical condition that causes vascular tumors to grow in his head and throat. "

Had the execution gone forward, it would have been the first since the botched attempt to lethally inject Clayton Lockett last month in Oklahoma. Lockett's procedure was suspended on April 29 due to a collapsed vein. He later died of a heart attack.

A federal court last week also halted the scheduled execution by Texas of a man who appealed his sentence by arguing he had a mental disability.

In his brief to the Supreme Court, Missouri's Attorney General said Bucklew was not entitled to a stay in part because the inmate had delayed bringing his suit until "less than two weeks before his scheduled execution even though he has known about his medical condition and his pending execution for years."

Attorney General Chris Koster outlined Bucklew's crime which occurred in 1996 when he raped his former girlfriend and shot and killed a man named Michael Sanders.

Koster noted that Missouri has carried out six executions using the one drug cocktail of pentobarbital in six months and that "no witness has seen anything inconsistent with those executions all being rapid and painless."

In the order, the Supreme Court left it up to the lower courts to decide "whether an evidentiary hearing is necessary."

It was only in 2008 that a fractured Supreme Court upheld Kentucky's lethal injection protocol which consisted of a three drug cocktail.

Chief Justice John Roberts, writing for himself and Justices Anthony Kennedy and Samuel Alito said, "Simply because an execution method may result in pain, either by accident or as an inescapable consequence of death, does not establish the sort of objectively intolerable risk of harm that qualifies as cruel and unusual."

Roberts said that for a risk of harm from execution to violate the 8th amendment "the conditions presenting the risk must be sure or very likely to cause serious illness and needless suffering and give rise to sufficiently imminent dangers. "

"We have explained" Roberts wrote, "that to prevail on such a claim there must be a substantial risk of serious harm, an objectively intolerable risk of harm that prevents prison officials from pleading that they were subjectively blameless for purposes of the Eighth Amendment."

Elisabeth Semel, who is the director of the Death Penalty Clinic at the University of California, Berkeley, School of Law says, "It would appear from the stay order, which is brief, though not unusually so, that the Supreme Court is persuaded Mr. Bucklew has made a showing sufficient to require the Eighth Circuit to give full consideration to his claim and, depending upon the circuit's determination, to order an evidentiary hearing."

Missouri, like several other states hit with shortages of drugs used to carry out executions, has changed its lethal injection protocols and refused to release information concerning the origins of the drug. Bucklew's lawyer say that more information is needed to determine the degree of pain that Bucklew could experience during an execution.

"I would emphasize," Semel says, that the state's insistence on secrecy with regard to the source of the compounded pentobarbital adds to the risk that Mr. Bucklew will suffer an agonizing execution, which the Eighth Amendment prohibits."