Last week, the Supreme Court responded to a petition from a death row inmate in Alabama containing an unusual demand: He wanted to be executed by firing squad. The prisoner, a 75-year-old man named Thomas D. Arthur, who was convicted of a murder committed in 1982, argued that if he was executed using the state’s default method, lethal injection, he would become the latest in a series of death row prisoners who have appeared to suffer for extended periods of time during their executions. Arthur contended that such a death would violate the Eighth Amendment, which protects prisoners against cruel and unusual punishment — but the firing squad would be an acceptable replacement.

The court rejected Arthur’s appeal over a furious dissent from Justice Sonia Sotomayor, who argued that of all the available options, the firing squad might well be the most humane. “In addition to being near instant, death by shooting may also be comparatively painless,” she wrote. “Condemned prisoners, like Arthur, might find more dignity in an instantaneous death rather than prolonged torture on a medical gurney.”

Despite being the default method of execution in the 31 states where the death penalty is still legal, the use of lethal injection has resulted in disturbing scenes where inmates appeared to be dying in excruciating pain, sometimes for an hour or more. Now, Arthur and Sotomayor are not alone in wondering whether the firing squad could be a preferable alternative to lethal injection; state legislators, lower court judges and other death row inmates have also proposed bringing back the firing squad. But will Americans allow the country to return to a method of execution that was rejected decades ago as too brutal and backwards?

Utah is the only state that has carried out an execution by firing squad in recent memory. But Oklahoma allows the use of the firing squad as a backup for lethal injection, and as recently as this month, Mississippi considered similar legislation to allow the use of the firing squad, electric chair and gas chamber, although the firing squad option was recently removed from the bill.

A central part of the case for firing squads is that these executions can be more difficult for states to mishandle. In her dissent, Sotomayor pointed out that firing squad executions were far less likely to have been botched in the past. Citing data compiled by political scientist Austin Sarat, she noted that about 7 percent of the executions by lethal injection between 1890 and 2010 were botched, meaning that they departed from the standard protocol set forth by the state. The number of botched firing squad executions, meanwhile, was zero.

If the number of botchings is a proxy for the effectiveness or humaneness of a particular form of execution, the data would seem to serve as a ringing endorsement of proposals like Mississippi’s. But Sarat, a professor at Amherst College, said that the numbers can tell us how frequently particular types of executions go wrong but not which method is the most humane. The broader conversation, he said, should be about whether a death penalty method is compatible with our social values and commitments, not whether we can prove that we’re minimizing the suffering of the condemned. “Are we really saying that a form of execution is legitimate just because it hasn’t been botched as frequently?” he said.

The relative rarity of firing squad executions should caution anyone against extrapolating too much from Sarat’s data. Of the 8,776 executions that took place between 1890 and 2010, only 34 used firing squads. Even before the advent of modern technologies such as electrocution, the gas chamber and lethal injection, firing squads were still relatively uncommon. Another data set of executions going back to the 17th century, compiled by death penalty historians M. Watt Espy and John Ortiz Smykla, shows that of 15,269 executions that took place in the United States between 1608 and 2002, only 142 were carried out by gunshot. Many of those 142 executions, especially those conducted in the 19th century or later, took place in Utah, which held on to the firing squad as a method of capital punishment long after other states had rejected it as antiquated and barbaric, in part because of an arcane Mormon belief in “blood atonement” — the idea that a murderer must literally shed his blood to be forgiven by God. From 1977, when the death penalty began to be implemented again after a short hiatus imposed by the Supreme Court, only three executions by firing squad have taken place. Even Utah finally removed the firing squad from the books in 2004, driven by concerns from legislators that continuing to offer it made the state appear primitive, although it was formally reinstated in 2015.

“Americans tend to want the death penalty to be as sanitary as possible,” said Andrew Novak, a professor at George Mason University who studies the death penalty in the U.S. and abroad. “It’s an act of state violence, but we don’t want it to be violent.”

The search for a swift and painless form of capital punishment began in earnest in the late 19th century, when hanging was increasingly seen as primitive and ineffective, while the firing squad was associated with the violence and anarchy of the Wild West. At first, the electric chair, which was adopted in 1890, seemed to be the solution; then, in the 1920s, lethal gas was introduced as an even more humane alternative. But neither delivered on their promise of painlessness and speed. Prisoners executed in the electric chair often had burns across their body, and inmates placed in the gas chamber appeared to be choking to death.

There’s little empirical or clinical research on the experience of death by execution: In one macabre experiment, conducted in 1938, a physician monitored the heart activity of a man being executed by firing squad and found that his heart essentially stopped functioning less than a minute after the shots were fired. A study conducted in 1993 attempted to measure pain during different forms of execution. It concluded that firing squad was one of the least painful methods — but because the study assumed that the executions went smoothly, it said the same of lethal injection. Dr. Jonathan I. Groner, a professor of surgery at Ohio State University, says that based on his experience as a surgeon and his research on the effects of lethal injection, he believes the firing squad is quicker and causes less suffering than other forms of execution. “There’s pain, certainly, but it’s transient,” he said. “If you’re shot in the chest and your heart stops functioning, it’s just seconds until you lose consciousness.”

The firing squad also has the advantage of being carried out by trained professionals, says Deborah Denno, a professor of law at Fordham University. Lethal injection, despite the fact that it was designed to mimic anesthesia, has been hamstrung by the fact that most physicians refuse to participate in executions. This leaves prison staff to perform a series of procedures that require professional medical skill. Firing squads, on the other hand, use professional marksmen. “For better or for worse, we have a lot of people in this country who are very good at firing a gun,” Denno said. But although the marksmen who carried out the firing squad execution in 2010 were chosen from a pool of volunteers, Novak noted that those who pull the trigger might still suffer from a form of post-traumatic stress. Vietnam recently abandoned the firing squad in favor of lethal injection, in part because of the distress experienced by the shooters.

It’s certainly possible to botch a firing squad execution, says Novak, who has studied executions in countries like Indonesia where the firing squad is more commonly used. “There are these ghastly stories about marksmen missing the target and the prisoner resuscitating and having to be shot again,” he said. These kinds of errors may be less likely in Utah, which has a detailed protocol for conducting firing squad executions, including a special chair with restraints. (In Indonesia, prisoners are usually tied to a stake, leaving more room for error.) Protocols, however, don’t guarantee success. “We have equally detailed regulations for lethal injection and still manage to mess those up,” Novak said. Sarat, too, is skeptical of the idea that trained marksmen would never make a mistake. “We don’t expect perfect performance from any other profession,” he said.

The fate of efforts to bring back the firing squad, in the end, may hinge less on proof of its effectiveness and more on the public’s willingness to stomach such an unequivocally violent form of execution. Despite all of the bad publicity around lethal injection, a poll conducted in 2014 found that 65 percent of Americans still believed it was the most humane form of execution; only 9 percent said the same of the firing squad. “We can debate all day about whether the firing squad is more predictable or less painful, but in the end it’s about what Americans are willing to tolerate,” Novak said. “And I just don’t think we’ll accept the idea of the state performing executions by shooting people, no matter what the science or the data says.”

CORRECTION (March 17, 10:10 a.m.): An earlier version of this article misstated how many executions were carried out by gunshot between 1608 and 2002, according to M. Watt Espy and John Ortiz Smykla’s database. It was 142, not 144.