In rejecting the inmates' claims, the court also lifted a stay of execution that it had granted earlier in the week in a case that placed Oklahoma's two highest courts at odds and prompted calls for impeaching justices on the Supreme Court.
Wednesday's decision paves the way for death row inmates Clayton Lockett and Charles Warner to receive a lethal injection at the Oklahoma State Penitentiary in McAlester. A stay issued on Tuesday by Gov. Mary Fallin remains in place for Lockett, but only until April 29, the same day Warner is scheduled to die.
Fallin spokesman Alex Weintz has said the governor is still reviewing the court's ruling and has not made a decision on what she will do. Weintz has said it is possible both men could be executed on April 29.
Telephone message left late Wednesday with attorneys for Warner and Lockett were not immediately returned.
Oklahoma Attorney General Scott Pruitt said the court's decision affirmed a longstanding precedent that the source of the execution drugs should remain confidential to avoid "intimidation used by defense counsel and other anti-death penalty groups."
"These death row inmates have not contested their guilt for murdering two innocent victims nor have they contested their sentences of death," Pruitt said. "The legal wrangling of the attorneys for Lockett and Warner has served only to delay their punishment for the heinous crimes they committed."
States that have the death penalty have been scrambling for substitute drugs or new sources for drugs after major drugmakers — many based in Europe with longtime opposition to the death penalty — stopped selling to prisons and corrections departments.
Oklahoma isn't the only state where the secrecy of execution drugs has been an issue. Courts in Missouri and Texas have rejected claims that secretive death-row procedures could expose inmates to painful executions. However, the Oklahoma inmates asked their question in a civil court, not a criminal one.
The nine-member Oklahoma Supreme Court caused an uproar Monday when it issued a 5-4 opinion that delayed the executions until the inmates' claims over drug-source secrecy were handled.
The justices are restricted to ruling on civil matters. But the Oklahoma Court of Criminal Appeals, which handles cases from inmates, said it wasn't authorized to weigh in on the request for a stay because the inmates challenged the execution procedures in civil court, not criminal.
The justices on the state Supreme Court so provoked some in the Republican-controlled Legislature that one member ordered articles of impeachment be drafted for the five justices in the majority, saying Wednesday they violated their oaths of office and engaged in a "willful neglect of duty."
On Wednesday, the justices reversed a lower court decision that said preventing the inmates from seeking information about the drugs used in lethal injections violated their rights under the state constitution. The high court said the inmates' constitutional rights weren't violated by keeping the drug sources secret.
In a concurring opinion, Justice Steven Taylor said the inmates' claims are "frivolous and not grounded in the law."
"The plaintiffs have no more right to the information they requested than if they were being executed in the electric chair, they would have no right to know whether OG&E or PSO were providing the electricity; if they were being hanged, they would have no right to know whether it be cotton or nylon rope; or if they were being executed by firing squad, they would have no right to know whether it be by Winchester or Remington ammunition," Taylor wrote. "I hope that this case ends any thought of future journeys down this path that has led this court to this day."
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