Burning at the stake. Firing squad. Hanging. Electric chair.

It is hard to imagine how these outdated methods of capital punishment might work their way into a serious discussion of capital punishment at the United States Supreme Court in the year 2015.

But that’s what happened on Wednesday as a lawyer for death row inmates in Oklahoma urged the justices to declare that the state’s lethal injection protocol violates the Eighth Amendment’s ban on cruel and unusual punishments.

At issue in the case is whether the first drug used in the state’s three-drug procedure, midazolam, is effective in rendering a condemned prisoner into a deep, coma-like unconsciousness.

The effectiveness of the first drug is crucial because medical experts say the second two drugs can cause excruciating pain before they bring death by shutting down the lungs and heart.

Midazolam has been used in executions in Ohio, Arizona, Florida, and Oklahoma. Within the past year, three executions – including one in Oklahoma – were botched with the condemned prisoners continuing to gasp and struggle long after they should have been in a coma-like level of unconsciousness.

A lawyer for the Oklahoma death row inmates, Assistant Federal Public Defender Robin Konrad, told the justices that midazolam is the wrong drug for the job. She said it is not effective enough and that its use creates an intolerable risk that the prisoner will suffer excessive pain during the execution process.

By midway through the session it was clear that the four justices on the court’s liberal wing were solidly behind Ms. Konrad’s argument.

But it was also clear that the court’s conservatives were troubled by a certain aspect of the case.

For many years Oklahoma and most other states in the country with capital punishment were able to carry out relatively painless executions by relying on one of two drugs to render the condemned prisoner into a deep state of unconsciousness. Those two drugs are sodium thiopental and pentobarbital.

In recent years, death penalty opponents initiated a campaign to dry up the supply of those drugs by pressuring the companies that produce them. The shortage of those two effective drugs prompted states like Oklahoma to turn to midazolam.

“Let’s be honest about what’s going on here,” Justice Samuel Alito told Konrad at one point. “Oklahoma and other states could carry out executions painlessly.”

He noted that the Supreme Court has upheld the death penalty – although it remains controversial. Justice Alito said death penalty opponents are free to try to change the laws and they are free to ask the court to overturn capital punishment.

“But until that occurs, is it appropriate for the judiciary to countenance what amounts to a guerilla war against the death penalty which consists of efforts to make it impossible for the states to obtain drugs that could be used to carry out capital punishment with little, if any pain,” he asked.

Justice Antonin Scalia chimed in: “The states have gone through two different drugs, and those drugs have been rendered unavailable by the abolitionist movement.”

But for the effort of the abolitionists, states would be conducting effective executions, Justice Scalia said. “You think we should not view that as relevant to the decision that you’re putting before us,” he asked Konrad.

Konrad replied that the unavailability of other effective drugs was not relevant to case before the court. She noted that there had been 11 executions using pentobarbital within the past year by other states able to obtain that drug.

“That doesn’t answer Justice Scalia’s and Justice Alito’s question,” Justice Anthony Kennedy said, a tone of exasperation in this voice. Justice Kennedy is likely to cast the deciding vote in the case.

“What bearing, if any, should we put on the fact that there is a method, but that method is not available because of opposition to the death penalty,” he asked.

It should have no bearing on whether a particular method used by a state is constitutional, Konrad replied. “It’s not relevant,” she said.

“There are other ways to kill people, regrettably, that are painless,” Justice Sonia Sotomayor noted. She mentioned using gas and a firing squad.

“Doesn’t a firing squad cause pain,” Justice Ruth Bader Ginsburg inquired.

Konrad said she wasn’t sure if a firing squad would violate the Eighth Amendment.

“You don’t know,” Chief Justice John Roberts asked. “Do you have a guess?”

He added: “Is there a reason that the states moved progressively to what I understand to be more humane methods of executive? Hanging, firing squad, electric chair, gas chamber?”

“You’re not suggesting that those other methods are preferable to the method in this case, are you,” Roberts asked.

“I’m not suggesting that, Mr. chief justice.”

Konrad noted that the Eighth Amendment provides a guarantee that execution methods will reflect the nation’s “evolving standards of decency.” That means execution methods that might have been acceptable in the past are no longer acceptable in a modern, more humane society.

Roberts asked for an acceptable alternative for Oklahoma to use in executing her clients.

Konrad hesitated.

“You have no suggested alternative that is more humane,” Roberts asked.

The lawyer said that Oklahoma had just passed a statute permitting use of nitrogen gas as a backup execution method if lethal injection was not available. But she declined to opine on whether nitrogen gas would be humane.

Both Justices Sonia Sotomayor and Elena Kagan cited medical evidence concerning how painful the second and third drugs are in a three-drug lethal injection. They likened it to being burned alive.

Justice Kagan asked Oklahoma’s Solicitor General Patrick Wyrick whether using an anesthetic that was not 100 percent reliable during an execution would violate constitutional protections.

“So suppose that we said, we’re going to burn you at the stake, but before we do, we’re going to use an anesthetic of completely unknown properties and unknown effects. Maybe you won’t feel it, maybe you will. We just can’t tell. And you think that would be OK,” she asked.

Solicitor General Wyrick responded that such a situation would pose an objectively intolerable risk of severe pain.

“That threshold showing would be incredibly easy to make in that case,” he said.

During her rebuttal argument, Konrad returned to that burned alive hypothetical. She said if a person was burned alive and it couldn’t be known whether appropriate anesthesia had been administered, the execution would be unconstitutional.

Justice Alito followed up with a broader question: “If an anesthesiologist rendered a person completely unconscious, and then the person was burned alive, would that be cruel and unusual punishment?”

“It could be,” Konrad replied.

Kagan interjected that the third drug in Oklahoma’s lethal injection protocol, potassium chloride, is similar to being burned alive if the first drug isn’t effective. “It’s being burned alive from the inside,” she said.

Alito pressed his question. “You think there are circumstances in which burning somebody at the stake would be consistent with the Eighth Amendment?”

“The founders say burning at the stake is unconstitutional. It’s cruel and unusual,” Konrad said. “But in your hypothetical, if there was a way to ensure that that was done in a humane way, there could perhaps be [a constitutional way to do it.]”

“That’s an incredible answer,” Alito replied. “You think that there are circumstances in which burning somebody alive would not be a violation of the Eighth Amendment?”

Justice Kagan responded: “You see, but potassium chloride is burning somebody alive. It’s just doing it through the use of a drug.”

The case is Glossip v. Gross (14-7955).

A decision is expected by late June.