In federal court testimony last week, doctors differed on whether midazolam is an appropriate execution drug, though the U.S. Supreme Court has ruled in 2015 that it is.
The decision was seen as a victory for Davis' lawyers, as well as the large number of death penalty opponents who have protested Hutchinson's plan.
The Republican governor had set an aggressive schedule of eight executions by the end of April, when the state's supply midazolam, a key lethal injection drug, expires. But the Supreme Court declined to intervene early Tuesday, leaving the state supreme court's stay in effect and sparing Davis' life for the time being.
On Monday evening, Don Davis had been given what was to be his last meal at the Cummins Unit, the Arkansas prison that houses the state's execution chamber. The U.S. high court is set to hold oral arguments on the request April 24.
McKesson alleges that the Arkansas Department of Corrections illegally obtained certain the execution drug Vecuronium in July 2016, by not disclosing they were buying the drug with the intent to execute prisoners.
"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", Assistant Federal Defender Scott Braden said in a statement.
Arkansas had run out of its supply of potassium chloride in January, but Gov. Asa Hutchinson said they would be able to procure a supply for the executions.
Davis was sentenced to death for the 1990 death of Jane Daniel in Rogers, Arkansas.
As state officials prepare to carry out a double execution Thursday ahead of a drug expiration deadline and despite the setback the U.S. Supreme Court delivered late Monday, lawyers for those condemned men look to be taking a different approach: claiming the prisoners are actually innocent.
There are many. The two set for execution Thursday, Lee and Johnson, both want more DNA testing in hopes of proving their innocence, though a Pulaski County judge on Tuesday rejected Lee's request for the enhanced tests.
"There are five scheduled executions remaining with nothing preventing them from occurring, but I will continue to respond to any and all legal challenges brought by the prisoners", Rutledge said.
The high court has tossed out two Texas death sentences this year - one because of racially discriminatory testimony, the other because of an outdated definition of intellectual disability. The issue in that case is about the sedative midazolam and whether its use in executions could violate inmates' Constitutional rights.
A different federal judge has issued a stay for an inmate who won a clemency recommendation from the state's Parole Board, while the state Supreme Court has issued one for another inmate pending more mental health tests.
In the current case, drug company McKesson obtained a temporary restraining order against Arkansas for allegedly obtaining a supply of drugs under false pretences, writes the New York Times. The company "is committed to ensuring that its property is only used in a manner consistent with our supplier agreement", the statement noted.
The justices also took direct action against Judge Griffen by barring him from hearing any death penalty, execution or drug protocal cases.
"ADC meant to use this product in connection with executions, a fact that was never disclosed to McKesson", the company said in the filing at a state court in Little Rock, the state capital.
The sedative has been used in botched executions, and some medical experts have claimed it is not proven to be effective, thus exposing an inmate to the risk of severe pain as the other drugs are administered.