In a one-paragraph order released in the early morning hours Tuesday, the nation's highest court declined to lift Davis' stay of execution granted by the Arkansas Supreme Court.
Two prisoners on death row for murder in the USA have escaped execution following a last-minute decision by a state Supreme Court.
The decision by the 8th U.S. Circuit Court of Appeals in St. Louis was independent of the Arkansas State Supreme Court ruling, meaning the state was barred from executing condemned killers Don Davis and Bruce Ward as scheduled on Monday evening, the Arkansas attorney general's office said.
The state would use a three-drug lethal injection protocol.
The inmates asked the eighth US Circuit Court of Appeals to take its time reviewing transcripts and rulings, rather than complete their work in two days as the state has asked.
There are five more executions scheduled before the end of April. The state's highest court granted a stay on Monday afternoon.
That decision "stirred a wave of consternation and threats on social media from state lawmakers and conservatives", member station KUAR noted on Saturday - because shortly before the decision, the judge was photographed protesting the death penalty at the gates of the Governor's Mansion.
The judge in question, Wendell Griffen, has since been removed from all cases involving the death penalty, under an order from the Arkansas Supreme Court, the Arkansas Democrat-Gazette reports. The state Supreme Court also lifted a lower court ruling preventing the state from using another lethal injection drug that a supplier said was sold to be used for medical purposes, not executions. The next executions are scheduled for Thursday.More news: AIADMK rules out change in CM, Palaniswami to stay
It was used in executions in three U.S. states in 2014 that took longer than usual. Two were scheduled to be executed by lethal injection in Arkansas on April 17. McKesson discovered that the drug was to be used for executions and demanded the state return the drug, promising a refund.
Their lawyers had argued they were mentally unfit to face execution and were denied proper assessment.
The state "intended to use this product in connection with executions, a fact that was never disclosed to McKesson", the company said in Tuesday's filing in state court in Little Rock.
Lawyers representing the inmates praised the decision of the Arkansas Supreme Court to stay, or temporarily suspend, the executions.
Bishop Taylor and Bishop Frank Dewane of Venice, Florida, the chair of the USA bishops' domestic justice and human development committee, both spoke out against the planned executions.
But Arkansas Attorney General Leslie Rutledge swiftly filed an application with the US Supreme Court to obtain permission to proceed with the execution of just Davis.
The State of Arkansas has yet to respond to the newest claim by McKesson. One of them, the sedative midazolam, has been associated with botched executions in Alabama, Arizona, Ohio and Oklahoma.
"What Governor Hutchinson is faced with is really an extraordinary situation", said Jim Guy Tucker, who, as a Democratic governor of Arkansas in the 1990s, oversaw seven executions.
(END OPTIONAL TRIM.) A spokesman for the state prison system, Solomon Graves, said the Arkansas authorities would be prepared to carry out the other executions that Hutchinson set.