The courts decision was the second time Don Davis has been granted a reprieve shortly before execution he came within hours of death in 2010.
Inmates Bruce Ward and Don Davis, the first two men scheduled to die, had requested a delay last week, citing the need to wait for the conclusion of a US Supreme Court case.
The court may be even more reluctant to do so now with new Justice Neil Gorsuch on board, especially because Gorsuch could be thrust into the uncomfortable position of taking a decisive and public death penalty stand very early in his tenure. But the Republican governor says he was heartened by other court rulings Monday that could pave the way for Arkansas to execute several more inmates before the end of April. Five U.S. Supreme Court justices must vote to vacate an execution stay.
Associate Justice Shawn Womack, writing in dissent, said Davis and Ward "had their day in court" and that the families are "entitled to closure and finality of the law".
In a statement, assistant federal defender Scott Braden praised the ruling.
Both inmates' lawyers claim that their clients are too mentally impaired to face capital punishment and were not offered proper mental health screening. His attorneys have said he is a diagnosed schizophrenic.
Attorneys had requested the stay while the U.S. Supreme Court takes up a separate case concerning inmates access to independent mental health experts.
That case, McWilliams v. Dunn from Alabama, is scheduled for oral argument next week and involves legal questions about expert testimony at criminal trials. The eight men are scheduled to be executed by lethal injection in Arkansas. 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.
In 2014, Oklahoma was the last state to try carrying out two executions on the same night, an effort that went badly awry. Arkansas contends it has acted legally. The state's attorneys are fighting to persuade judges to allow the executions - and to make the decision quickly. The state scheduled the executions to happen before its supply of midazolam, a lethal injection drug, expires at the end of April.
It was used in executions in three USA states in 2014 that took longer than usual.
It is also appealing against Mr Griffen's order that the prison system cannot use a paralysing drug until he could determine whether the state obtained it properly.
The Arkansas Supreme Court had already blocked Ward's execution due to questions about his mental competency.
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Vice President Mike Pence waves before leaving for Japan, at Osan Air Base in Pyeongtaek, South Korea, Tuesday, April 18, 2017. Indonesia is one of 16 countries under review for having a trade surplus with the United States.
The inmates say midazolam is unsuitable because it is not a painkiller and could subject them to a cruel and unusual punishment in violation of the US Constitution.
The judge determined that their concerns were sufficient to halt the executions for the time being, to allow the issue to be considered by the courts.
Rutledge was quick to respond to the Supreme Court's decision.
The European Union on Wednesday urged Hutchinson to commute the death-row inmates' sentences.
The US Court of Appeals for the 8th Circuit on Monday reversed a federal judge's broader stay on the executions, clearing the path for deaths scheduled to take place later this month to proceed.
(Stephen B. Thornton/The Arkansas Democrat-Gazette via AP).
The court battles are playing out on multiple fronts as the state's supply of midazolam expires on April 30.
If the rulings are overturned by Monday night, the state will be prepared to execute at least one inmate, according to local TV station KATV.
Despite the setbacks, Attorney General Leslie Rutledge said Arkansas would press ahead with other planned executions, including two set for Thursday Ledell Lee and Stacey Johnson.
"Davis' exact schedule for the day is confidential but as part of the death protocol, he will be meeting with counsel and a spiritual adviser", KATV reports.
Three Arkansas justices dissented, with Associate Justice Shawn Womack writing Ward and Davis "had their day in court, the jury spoke and decades of appeals have occurred".