The Supreme Court heard arguments today about a method of execution used in a number of states that reportedly violates the Constitution's ban on cruel and unusual punishment. 

Shannon Bream reported tonight that death row inmates in Oklahoma are pleading to outlaw the sedative drug called midazolam.

Bream said that "critics argue there's no proof it renders a prisoner completely unconscious and unable to feel pain before death."

She explained that there were two drugs on the market used in the past to induce a "coma-like state."

Bream said that "they were believed to be entirely effective, but death penalty opponents have successfully lobbied pharmaceutical companies to make sure those drugs are unavailable."

Read more from the Associated Press:

But Wednesday's session, lasting just over an hour, featured broader complaints from conservative justices that death penalty opponents are waging what Justice Samuel Alito called a "guerrilla war" against executions by working to limit the supply of more effective drugs.

On the other side, among the court's liberals, Justice Elena Kagan contended that the way states carry out most executions amounts to having prisoners "burned alive from the inside."

The debate came on the court's last argument day until fall, and a year to the day after a problematic execution in Oklahoma gave rise to a lawsuit from death row inmates over the use of midazolam.

The outcome of the case could turn on a rather narrow question involving the discretion of the federal trial judge who initially heard the lawsuit. He ruled against the inmates, and a unanimous three-judge panel of the federal appeals court in Denver affirmed that ruling.

But justices on both sides gave voice to larger concerns.

"There are other ways to kill people, regrettably, that are painless," Justice Sonia Sotomayor said.

Bream stated that the Supreme Court is expected to make a decision by late June. 

Watch the clip above. 

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