Lawmakers in several states this year have put forward legislation to revise alternative methods of capital punishment in the face of a shortage of drugs once used for executions as well as legal challenges to new lethal "cocktails."
Oklahoma was among those states, and it had faced lawsuits to stop the execution of convicted rapist and murderer Clayton Lockett, who died on Tuesday night of an apparent heart attack minutes after a medical official on the scene called a halt to the botched process, saying something had gone wrong with the lethal injection.
"As long as there are problems with lethal injection, and there have been and there will be, there will always be legislators determined to kill people with some other method," said Rick Halperin, director of the Embrey Human Rights Program at Southern Methodist University in Dallas.
So far this year, lawmakers in Tennessee have passed a measure to allow the state to electrocute death row inmates if it could not obtain drugs for lethal injections.
A Missouri lawmaker introduced a bill to set up firing squads and a gas chamber should there be problems with lethal injections. In Wyoming, lawmakers were also considering firing squads.
The Virginia House in January passed a measure to make electrocution the default death penalty method if lethal injection drugs cannot be procured, but the bill was halted in the state Senate.
The electric chair was used for years after the U.S. Supreme Court reinstated capital punishment in 1976, but it has also produced some horrific results.
There were reports in both Virginia and Alabama of an inmate being set on fire in the early 1980s, with the smell of charred flesh wafting through the death chambers.
In response, several states led by Texas began using lethal injections in the early 1980s, with the method of execution seen as more humane.
It is now the primary method of execution in all of the 32 U.S. states that use the death penalty as well as for federal death row convicts.
Since 1976, just over 1,200 inmates have been executed by lethal injection while 158 were electrocuted, 11 put to death in a gas chamber, three hanged and three killed by firing squad, according to the Death Penalty Information Center, a capital punishment monitoring agency.
CRUEL AND UNUSUAL
Eight states still have electrocution on their books as an alternative method of execution, but with caveats. For example, Oklahoma can use the electric chair if its lethal injection protocol is found to be unconstitutional.
Virginia allows some inmates to die in the electric chair if they chose to do so. Its last electrocution using the chair was in 2013 when it put inmate Robert Gleason to death.
Larry Fitzgerald, a former spokesman for the Texas Department of Criminal Justice who has witnessed scores of executions, said the results of the state's lethal injections were always the same - with the inmate being rendered unconscious and then dying from drugs designed to stop breathing and stop the heart.
About five minutes after all the drugs of a three-drug cocktail were administered, a physician would be called in to pronounce death.
However, there were a few rare times when inmates blurted "I can feel it," or "I can taste it," after the injection, Fitzgerald said.
The U.S. Supreme Court has ruled that executions do not need to be painless. In a pair of cases out of Kentucky, the court in 2008 dismissed the idea that the potential for pain made the three-drug cocktail method of execution unlawful.
"Simply because an execution method may result in pain, either by accident or as an inescapable consequence of death, does not establish the sort of 'objectively intolerable risk of harm' that qualifies as cruel and unusual," Chief Justice John Roberts wrote then.
The Eighth Amendment to the U.S. Constitution bans cruel and unusual punishment.
Megan McCracken a lawyer at the University of California, Berkeley School of Law's Death Penalty Clinic said that although lethal injections appear serene, the inmate can be suffering greatly.
"The prisoner could be conscious and in extraordinary agony, but once that paralytic is administered, we would never see it," McCracken said.
The lethal injection process in the United States underwent a fundamental change in 2011, when drug company Hospira stopped making sodium thiopental, due to concerns about its widespread use in executions. It was the lone U.S. manufacturer of the drug.
The drug was an anesthetic that would render a person unconscious before the other drugs that would cause death were administered.
Texas changed to a single drug while other states scrambled to develop new lethal injection protocols.
The botched execution in Oklahoma has raised questions on whether these new protocols could be ruled as cruel and unusual punishment by the courts.
"This is really going to make the courts demand a whole lot more and they are not going to be as quick to allow executions to go forward unless the state can prove it knows what it is doing," said Richard Dieter, executive director of the Death Penalty Information Center.