By Jon Herskovitz
(Reuters) - Arizona has reached an agreement with lawyers for death row inmates that would prohibit a sedative that has been used in executions by lethal injection that took longer than usual or were botched in several states.
According to the settlement filed late on Monday in a federal court in Phoenix, Arizona "will never use again" the sedative midazolam, or related products, as a part of a drug protocol for lethal injections.
Midazolam is a valium-like drug its critics contend does not achieve the level of unconsciousness required for surgery and is therefore unsuitable for executions.
States have faced legal challenges on their lethal injection mixes after a sales ban imposed by U.S. and European pharmaceutical makers on chemicals states had once used.
"Time after time, midazolam has failed to keep condemned prisoners adequately anesthetized and to bring about a quick, humane death," said Dale Baich, one of the attorneys for the seven death row inmates who brought the suit.
The Arizona Department of Corrections was not immediately available for comment.
Midazolam has been used in executions in Arizona, Ohio and Oklahoma. In some instances, witnesses said convicted murderers twisted on gurneys before dying.
Its use was again questioned after an execution in Alabama this month of a convicted murderer who heaved and coughed after drugs were administered on the death chamber gurney for 13 minutes before dying.
Midazolam was used along with a narcotic in Arizona's last execution, which was for convicted murderer Joseph Wood in 2014. He was seen gasping for air during a nearly two-hour procedure where he received 15 rounds of drug injections. Lethal injections typically result in death in a matter of minutes.
Supporters of midazolam have said it is an effective chemical, the use of which has been authorized by the U.S. Supreme Court.
In a 5-4 ruling in June 2015 in support of midazolam, Supreme Court Justice Samuel Alito wrote that death row inmates in Oklahoma challenging its use had, among other things, failed to show there was an alternative method of execution available that would be less painful.
This year, U.S. pharmaceutical company Pfizer Inc. halted sales of its products for use in executions over similar concerns. This includes midazolam, pancuronium bromide, which can be used as a paralytic agent that halts breathing, and potassium chloride, which can cause cardiac arrest.
(Reporting by Jon Herskovitz; editing by Grant McCool)