Utah, the only U.S. state in the past 40 years to carry out a death sentence by firing squad, is poised to bring back the executions if the state cannot find a supply of the drugs used in lethal injections. Here's a look at how some other states are dealing with the nationwide shortage:
The U.S. Supreme Court is poised to review Oklahoma's use of the sedative midazolam in executions, and state legislators are considering the use of nitrogen gas to kill death-row prisoners. The sponsor of the nitrogen bill says the gas would gradually deprive inmates of oxygen, resulting in a painless death.
The method has never been used in an execution in the United States. If the effort passes, nitrogen would be the state's first alternative to lethal injection. The bill was prompted by the botched execution of an inmate last April. Clayton Lockett struggled against his restraints after attendants administered lethal drugs through a poorly placed intravenous line.
Since the state's last execution in 2005, inmates successfully argued in court that legislators ceded too much power over death row protocols to Arkansas' Correction Department. A subsequent lawsuit claims new protocols put inmates at risk of an agonizing death. In this year's legislative session, one lawmaker suggested abolishing the death penalty, but another lawmaker whose daughter was murdered in 1999 wants firing squads as another option for executioners.
Idaho allows prison officials to choose one of four options for lethal injection executions, depending on which chemicals are available. However, the state execution policy also gives both the Idaho Department of Correction director and the chief of prisons operations the power to change the execution procedure at any time, based on their own discretion.
Idaho law once allowed execution by firing squad, though the option was never used. It was removed from the books in 2009.
Last year, Idaho prison officials considered asking lawmakers to bring back the state's firing squad, but axed the plan after determining it would cost at least $300,000 to set up the squad.
The Wyoming Legislature has considered the use of firing squads in the past two legislative sessions. Republican state Sen. Bruce Burns, who introduced the bills, said he considers the gas chamber to violate the constitutional prohibition against cruel and unusual punishment and would opt for using the firing squad because it would be the cheapest option.
In Tennessee, legal challenges to lethal injection and difficulty obtaining drugs have stalled planned executions for more than five years. Several death-row inmates have died in prison while awaiting execution.
Last year, the Tennessee Legislature attempted to jump-start the process by reinstating use of the electric chair. A new law allows inmates to be put to death by electrocution if the state is not able to obtain lethal injection drugs or if lethal injection is ruled to be unconstitutional.
Texas is almost out of the drug it uses to execute inmates. The state is scheduled to execute a Mexican mafia hit man on Wednesday using its second-to-last dose of pentobarbital, leaving authorities with enough of the powerful sedative to carry out just one more execution. By far America's most active death penalty state, Texas has executed 521 inmates since 1982, when it became the first state to use lethal injection. The state is searching to replenish its pentobarbital supply.
Ohio executions are on hold as the state struggles to find supplies of lethal-injection drugs. After running out of its two previous drugs, the state switched to a never-tried two-drug combination of midazolam, a sedative, and hydromorphone, a painkiller.
In that method's only use, in January 2014, inmate Dennis McGuire repeatedly snorted and gasped during his 26-minute execution, the state's longest. Ohio postponed executions as lawsuits were filed over McGuire's death, and eventually the state dumped the two-drug combo last year.
Instead, the prisons department said it will use one of two drugs in future executions: pentobarbital or sodium thiopental. The catch is Ohio doesn't have either drug and both are virtually impossible to obtain except in specialty batches known as compounded drugs. The state has delayed all executions until 2016 and beyond.