Two upcoming executions in the southwestern U.S. state of Oklahoma were postponed by courts on Tuesday because of a shortage of lethal injection drugs.
Prison authorities, at the center of a controversy over the deadly drug supplies, have also said they hope to change the execution method.
An appeals court in Oklahoma ordered that the executions, scheduled for March 20 and 27, be pushed back to April 22 and 29, respectively.
Oklahoma allows execution by electric chair, if the inmate chooses it or if lethal injection is found to be unconstitutional. Authorities could also try to obtain the necessary drugs from a compounding pharmacy.
However, such pharmacies, unregulated by the FDA, have also proven controversial.
The two death row inmates, Clayton Lockett and Charles Warner, both convicted of rape and murder, have argued it is their constitutional right to know the origin and composition of the drugs used in the lethal injection, to be certain they will not be made to suffer "cruel and unusual punishment".
In its decision, the appeals court noted the state "revealed that as of Monday, March 17, 2014, the Oklahoma Department of Corrections remained without the drugs ... needed to carry out the lawful sentence of death".
"According to the (Oklahoma) Attorney General, 'pentobarbital remains in short supply' and 'vecuronium bromide is now difficult, if not impossible even for hospitals and medical professionals to obtain,'" the court document said.
"The State declared that it had pursued 'every feasible option to obtain the necessary execution drugs' but its 'Herculean' efforts so far had been unsuccessful," the court added in its decision.
Warner's lawyer, Madeline Cohen, was "relieved" by the postponement, and hopes "no execution will go forward until we are able to obtain full information about how Oklahoma intends to conduct those executions".
Oklahoma's right to keep secret its execution protocol will be considered in an upcoming hearing.
Since European manufacturers began refusing to sell the most commonly used anaesthetic -- pentobarbital -- for human executions, several US states have found themselves confronted with shortages, and are now seeking an alternative, which has led to an increase in court cases over the issue.
Lockett was sentenced to death in 2000 for raping and murdering a woman. Warner was sentenced in 1997 for raping and murdering an 11-month old baby girl.
[Image via Agence France-Presse]