Seven hundred and forty-four people have been executed in the United States over the last 15 years. Just nine of them, according to the nonprofit Death Penalty Information Center, were killed by electrocution.

But that number may soon rise. Amid controversies over lethal injection drugs, several states are in the midst of reintroducing the electric chair as a method of state-sanctioned capital punishment.

The Virginia House of Delegates recently passed legislation that would require the use of the electric chair for condemned prisoners if lethal injection drugs cannot be found. Similar legislation passed Alabama's state house last year and became law in Tennessee the year before.

This renewed interest in the electric chair is in part a result of the increasing difficulty of obtaining the drugs necessary to carry out lethal injections, which has been the execution method of choice since the Supreme Court reinstituted the death penalty in 1976.

It is worth re-examining why the electric chair fell out of favor in the first place.

Death by electrocution was originally introduced in the 1880s as a way to kill cattle, lame horses, donkeys and stray animals. It was quickly proposed as a way to execute criminals, as a superior method to hanging. Thomas Edison was a big supporter of execution by electrocution. He would demonstrate the killing power of electricity by staging press conferences at which he would shock stray cats and dogs to death.

Well over a thousand electrocution executions were performed in the 20th Century through 1972, when a moratorium on capital punishment was declared. It was lifted in 1977, and some 150 have been carried out since then.

But electrocution has increasingly been seen as inefficient at best and inhumane at worst. In an execution by electrocution, the condemned is strapped into a wooden chair and has electrodes placed on his legs and head. Electricity is then sent through the body. In theory, the first jolt is supposed to bring about unconsciousness; the second is supposed to damage the vital organs and cause death.

But often, that's not the way it works. In his book Old Sparky: The Electric Chair and the History of the Death Penalty, Anthony Galvin tells the story of several horrific death chamber scenes. One was the 1982 electrocution execution of Frank J. Coppola, who was put to death in Virginia. As Galvin describes it:

"An attorney who was there said that it took two long jolts of electricity to kill Coppola. The first did not stop his heart. During the second fifty-five-second-long jolt, witnesses could hear the sound of sizzling flesh and Coppola's head and leg both caught fire. Smoke filled the small death chamber, making it difficult to see the writhing victim through the haze."

Other electric chair horror stories involve spewing blood, the odor of burning flesh and in some cases flames erupting from the prisoner's head.

"Even when it goes right," Galvin writes, "smoke rises from the body of the convict and the small execution chamber reeks of charred flesh. Prison officers habitually soak their clothes overnight before washing them to get rid of the smell after an execution."

There's little reason to think these gruesome stories wouldn't repeat themselves if electrocution were re-introduced. For one thing, the equipment used in electric chairs has not been improved over the years.

The barbarity of electrocution may be part of its appeal, at least to some. When Alabama was debating legislation to bring back the electric chair in 2015, bill sponsor Lynn Greer said, "The system we have today, we all know it is not working. It may be working for the criminals, but it is not working for the victims. To me, this makes common sense."

Another legislator said, "I am backing [the bill] 100 percent because I think we have done enough to protect the people on death row, and I think we should start protecting those who walk across the streets of this state."

As with many of America's most vexing public policy questions, the debate over the death penalty will likely end up being decided by the Supreme Court. The court has never declared a method of execution unconstitutional. And it has upheld the use of the electric chair on at least two occasions. But several state courts have recently outlawed the electric chair as violating the constitutional ban on cruel and unusual punishment. And many watchers of the court, which has ruled on the death penalty 17 times in the last 15 years, believe it will do the same soon.

The debate surrounding the death penalty boils down to one essential question: What is the purpose of capital punishment? Is it to kill with clinical efficiency so as to give victims and their loved ones some sense of justice and closure? Or is it also to make the condemned suffer?

How that question is answered — by the courts, legislatures and society as a whole — will go a long way in determining whether the electric chair is swept into the dustbin of history or whether it remains as a relic of a more barbaric past.

Daniel Allott is deputy commentary editor for the Washington Examiner