Justices also denied an attempt by makers of midazolam and potassium chloride - the two other drugs in Arkansas' execution plan - to intervene in McKesson's fight over the vecuronium bromide.
Arkansas' aggressive effort to conduct its first executions since 2005 stalled for a second time this week when courts blocked lethal injections set for Thursday, prompting Gov. Asa Hutchinson to complain that state judges aren't honoring the decisions jurors made when sentencing the prisoners to death.
Arkansas officials entered this week hoping to begin an unprecedented wave of executions, but court orders have imperiled those plans and left unclear whether the state will be able to carry out any of the lethal injections.
Jason McGehee, who was to be put to death on April 27, received a month-long stay two weeks ago because of a parole board's clemency recommendation. "When I set the dates, I knew there could be delays in one or more of the cases, but I expected the courts to allow the juries' sentences to be carried out since each case has been reviewed multiple times by the Arkansas Supreme Court, which affirmed the guilt of each".
But amid public opposition to the death penalty - including protests in the state capital Little Rock including actor Johnny Depp and a judge linked to one of the cases - lawyers obtained stays for three other executions. The legal setbacks at one point prompted the state's previous attorney general, Dustin McDaniel, to declare Arkansas' death penalty system "broken".
"I am both surprised and disappointed at the last minute stay by the Arkansas Supreme Court", Hutchinson said in a statement.
An eighth inmate, Jason McGehee, previously won a stay from a federal judge regarding his clemency schedule, and Arkansas has not appealed that ruling. One of those winners voted for Monday's night stay. Jeremy Hutchinson, who chairs the Senate Judiciary Committee and is the nephew of the governor.
McKesson Corp., a San Francisco-based medical supply company, "claimed that the state deliberately circumvented them to use the drugs for executions". But courts have blocked three of those executions from going forward. Anti-death penalty supporters Abraham Bonowitz, left, and Randy Gardner wait near their taped off "protest corral" outside the Varner Unit late Monday, April 17, 2017 near Varner, Ark. Once her order was in, the state filed a notice that it would appeal. None of the campaign material mentioned the death penalty. Goodson had touted her commitment to conservative values, while Kemp said in a campaign ad he would be guided by "prayer, not politics". A federal judge this month halted the last of the executions.
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If the election is approved Wednesday, Parliament will be dissolved on May 2, sparking nearly six weeks of campaigning. May's call for an early election came after firm assurances that she would not seek a new election before 2020.
The Arkansas Supreme Court is allowing the state to use a lethal injection drug in upcoming executions, despite a supplier's complaint that it was sold to the state to be used only for inmates' medical care. The court also barred an anti-death penalty circuit judge from participation in cases or laws involving capital punishment, and lifted his order blocking the state from using a lethal injection drug in the planned executions.
The court hasn't explained its reasoning in any of its one-page stay-of-execution orders for the three inmates.
The first, a ruling from the Arkansas Supreme Court on Wednesday, granted a stay of execution to prisoner Stacey Johnson, who is scheduled to die tonight.
"We've established that modern DNA testing methods can prove Mr. Johnson's innocence, and Arkansas law clearly established that Mr. Johnson is entitled to that testing", said Karen Thompson, a staff attorney with the Innocence Project, on Tuesday after the appeal was filed.
One of the three dissenting judges issued a blistering criticism of Monday's ruling sparing the first two condemned inmates. But the 8th U.S. Circuit Court of Appeals reversed that order Monday, and the inmates appealed that decision to the U.S. Supreme Court.
Another justice objecting to the rulings, Rhonda Wood, wrote in a dissent that Wednesday's stay "gives uncertainty to any case ever truly being final in the Arkansas Supreme Court".
The situation is a familiar one for Rebecca Petty, whose daughter's killer was granted a reprieve by federal courts hours before his execution in 2004.