Pulaski County Circuit Judge Alice Gray blocked the state from using the drug vecuronium bromide, siding with McKesson Corp., which had argued that it sold Arkansas the drug for medical use, not executions.
Arkansas officials have said they can not obtain the drug from another source.
The second round of executions planned for this week are now on hold as legal challenges play out in courts in Arkansas and Washington D.C.
Arkansas had initially scheduled eight inmates to die over an 11-day period in April - the fastest pace of executions in decades.
As lawyers for condemned inmates press the case for delay in state and lower federal courts, the Supreme Court receives information about developments and, eventually, copies of those decisions. Legal rulings have put the others in doubt.
The Supreme Court has the final say on nearly every execution, and the justices reject all but a few emergency appeals by inmates.
This story has been corrected to show that the inmate's name is Ledell Lee, not Lendell Lee. Their one-paragraph order did not elaborate on why.
A judge in Little Rock has blocked the state from using one of the drugs in Arkansas' execution protocol because a company says the state misled it into providing the drug for lethal injections.
Later, a spokesman for Correct Care Solutions sent an email to the Arkansas Democrat-Gazette saying the company "had absolutely no involvement in the purchase of drugs used for the goal of execution, nor did its doctor". Outside groups and the candidates spent more than $1.6 million past year on a pair of high court races that were among the most fiercely fought judicial campaigns in the state's history.
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Lawyers for the state of Arkansas are trying to light a fire under a judge who has been slow to file written paperwork involving a death penalty case. The state concedes the pair will not be put to death this month. Johnson's attorneys have sought more DNA testing that they say could exonerate him.
Arkansas' attempt to carry out its first execution in almost 12 years wasn't thwarted by the type of liberal activist judge Republicans regularly bemoan here, but instead by a state Supreme Court that's been the focus of expensive campaigns by conservative groups to reshape the judiciary.
McKesson's suit marks the first time in U.S. legal history that a private company has brought direct legal action to prevent the misuse of medicines in executions.
Arkansas wants to appeal Gray's order, but needs a written order from her to do so. Its lawyers filed paperwork with the state Supreme Court on Thursday morning asking it to order her to submit a formal order.
The Arkansas Supreme Court halted one of two executions set for Thursday, but in what could be a more severe setback, a judge barred the state from using one of the lethal drugs.
Governor Asa Hutchinson set the unprecedented schedule due to one of the drugs in the state's lethal injection mix expiring at the end of the month.
The state originally planned to carry out eight executions to occur over an 11-day period in April, which would have been the most by a state in such a compressed period since the USA supreme court reinstated the death penalty in 1976.
"In its efforts to "enforce the law" Arkansas has ridden roughshod over private companies' legal agreements and the interests of Arkansas patients, and today's ruling shows this will not pass unchallenged".
But while Goodson voted to stay the three executions, so did the conservative-backed candidate who beat her in the chief justice race, Dan Kemp.