The developments capped a day of waiting, preparation and a series of legal clashes. Although Mr. Davis and other prisoners whose executions had been scheduled for this month had already won stays from a federal judge in Little Rock, the United States Court of Appeals for the Eighth Circuit, in St. Louis, reversed the order, leaving the surprise decision by the state justices as the sole obstacle to the first lethal injection in Arkansas since 2005.
The most prominent legal battles ahead of Mr. Davis’s scheduled execution focused on the constitutional questions that have swirled around Arkansas’s death penalty procedures and a lethal injection drug, midazolam. Critics of the drug have argued that midazolam, a sedative, fails to render a prisoner sufficiently insensate to the pain of other ingredients used in lethal injections.
But Mr. Davis ultimately won a life-sparing reprieve on a matter that was entirely different: whether he should be executed as the United States Supreme Court considers a case about whether poor defendants with mental health problems are entitled to expert witnesses to aid them in preparing and presenting their cases.
Although the Supreme Court has never directly addressed whether such experts must be independent of prosecutors, the justices had long planned to hear arguments on that question next week in a case involving a prisoner from Alabama, James E. McWilliams. The possibility of a ruling that would affect Mr. Davis’s case, the Arkansas justices concluded, was enough to warrant stopping his execution.
The state ruling also applied to Bruce Ward, an Arkansas prisoner whose execution, originally scheduled for Monday, was already the subject of an unrelated stay.
“Both Mr. Ward and Mr. Davis were denied independent mental health experts to help their defense attorneys investigate, understand and present these critical mental health issues to the jury,” Scott Braden, an assistant federal defender who represents both men, said in a statement. “The Arkansas Supreme Court recognized that executing either man, before the court answers this question for Mr. McWilliams, would be profoundly arbitrary and unjust.”
The Alabama case that will go before the Supreme Court next week involves claims by Mr. McWilliams’s lawyers that his rights were violated when a court-appointed psychologist prepared a report that was distributed to both sides. Lawyers for the state responded that there was no right to a “partisan psychiatrist” and that “a neutral court-appointed psychiatrist who is equally available to both parties” was sufficient.
A decision in that case is expected by June. But the Arkansas court’s choice to stop Mr. Davis’s execution could extend his case for much longer, perhaps years, because the state is on the verge of having part of its drug supply lapse. A spokesman for Mr. Hutchinson said he did not believe that Mr. Davis could be put to death before the state’s midazolam expired at the end of this month.
Mr. Davis did not seek executive clemency for his conviction for the death of Jane Daniel, whose husband found her in a pool of blood at home in Benton County.
“Somebody got hurt,” Mr. Davis told his roommates after the October 1990 murder, according to a court ruling. He fled west and was arrested in New Mexico.
Some of the most vocal opponents of the death penalty at recent protests in Arkansas had been wrongly on death row themselves. Watch them deliver a petition to the governor’s office.
Recalling Ms. Daniel’s murder, Mr. Davis also said in that interview, “There is nothing in this world that I wouldn’t give to change that moment.”
Mr. Davis has repeatedly faced the threat of lethal injection — he came within hours of being put to death in 2010 — and Ms. Daniel’s daughter noted last month that she had traveled to Pine Bluff, near the prison, four times for executions that were eventually called off.
In a sharply worded dissent on Monday, Associate Justice Shawn A. Womack of the State Supreme Court complained about the delay that allowed Mr. Davis and Mr. Ward, who was also convicted of capital murder, to live.
“The petitioners had their day in court, the jury spoke, and decades of appeals have occurred,” Justice Womack wrote. “The families are entitled to closure and finality of the law.”
In a separate order on Monday, the Arkansas justices forbade a circuit court judge in Pulaski County, Wendell Griffen, from hearing cases related to capital punishment after he participated in a protest against the death penalty last week. The State Supreme Court also referred Judge Griffen to the Arkansas Judicial Discipline and Disability Commission.
The episode involving Judge Griffen, who on Friday ruled in a case about one of Arkansas’s other execution drugs, and Monday’s other developments added to this state’s complex and high-profile history with the death penalty. As a presidential candidate and Arkansas governor in 1992, Bill Clinton left the campaign trail to preside over an execution.
Later, in 1994, Arkansas was the site of the nation’s first triple execution in 32 years. Arkansas has repeatedly conducted double executions, and in 2015, a poll commissioned by the University of Arkansas showed overwhelming support for capital punishment here.
But Mr. Hutchinson set off an international furor when, in February, he scheduled eight executions that were to take place over less than two weeks in April. The schedule, death penalty researchers and historians said, was unequaled in the modern history of capital punishment in the United States, which reinstated the death penalty in 1976.
Mr. Hutchinson suggested he had little choice: With Arkansas’s midazolam supply set to expire this month, the authorities did not believe they would be able to restock it easily, effectively imposing a moratorium on the death penalty.
Although the schedule narrowed as judges issued stays of execution, Mr. Hutchinson faced pressure to back away from his plans, and the Governor’s Mansion in Little Rock was the scene of protests.
“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. “I can’t put myself in his shoes, but I’m profoundly grateful that I was never confronted with that problem.”
A spokesman for the state prison system, Solomon Graves, said the Arkansas authorities would be prepared to carry out the other executions that Mr. Hutchinson set.
“The Department of Correction’s attention now shifts to the executions that are scheduled for Thursday,” Mr. Graves said. “We are under the impression, and under the assumption, that those executions will be carried out as scheduled.”
They are scheduled for 7 p.m. on Thursday.