ST. LOUIS (AP) - The Missouri Supreme Court on Tuesday declined to set execution dates for six condemned killers, saying doing so is "premature" until the courts decide if Missouri's new execution method is constitutional.
Missouri Attorney General Chris Koster in May asked the court to set the execution dates, the same month the Missouri Department of Corrections adopted a new execution protocol that uses a single drug, propofol.
"Until the parties promptly resolve the issue of the use of propofol as contemplated by the department of corrections' protocol, ruling on the motion to set execution date is premature," the court ruling stated Tuesday. A spokeswoman for the Supreme Court declined to elaborate.
Koster called it disappointing.
"The Court had the option of setting execution dates, which would have effectively imposed deadlines on lower court challenges to the execution protocol," Koster said in a statement. "The Attorney General's Office will continue to do all we can to expedite the protocol-challenge cases."
Propofol, perhaps best known as the drug that killed pop star Michael Jackson in 2009, has never been used as an execution drug. A lawsuit filed by death row inmate David Zink claims its use could violate the constitutional guarantee against cruel and unusual punishment.
Zink was not among the six inmates whose execution date was sought by Koster. Those inmates included David Barnett, Jeffrey Ferguson, Joseph Franklin, Allen Nicklasson, William Rousan and Herbert Smulls. All six were convicted of first-degree murder.
Modern U.S. executions have used a nearly identical three-drug method until recently. One drug, sodium thiopental, is no longer available because its maker won't sell it for use in executions.
States have scrambled to find substitutes. Other states have gone to single-drug methods, but Missouri is the first to turn to propofol, an anesthetic.
Cheryl Pilate, an attorney for Smulls, wrote in a filing to the Supreme Court this spring that propofol has been known to cause extreme pain in some patients, even in normal doses. She wrote the Missouri plan calls for a dose 15 times greater than normal, potentially increasing the risk of pain and suffering. St. Louis attorney Richard Sindel made a similar argument on behalf of Barnett.
Missouri executed 66 men between 1989 and 2005, but has executed just two since, as courts have weighed constitutional challenges to the death penalty. There are 46 men on death row.