Attorney General Holder: We shouldn't be executing people right now

Attorney General Eric Holder called on Tuesday for a national halt of the death penalty until the Supreme Court determines the constitutionality of lethal injection.

"Fundamental questions" surround the death penalty, Holder said, among them, "whether or not lethal injection is consistent with our Constitution."

"From my perspective, I think a moratorium until the Supreme Court has made that decision would be appropriate," Holder concluded.

In late January, the Supreme Court agreed to hear a challenge from four Oklahoma inmates regarding the state's use of midazolam as the first of three drugs in a lethal injection cocktail.

When Ohio used midozolam for the first time in early 2014 to execute Dennis McGuire, he struggled and gasped for air for nearly 10 minutes before his heart stopped. Arizona also used midozolam in Joseph Wood's lethal injection. It took nearly two hours for him to die.

Most states had previously used pentobarbital, a drug approved for executions, in lethal injections - until its Danish manufacturer refused to continue selling the drug to the US because it's used for the death penalty.

Florida also uses midozolam for lethal injections, but the state has suspended executions until the Supreme Court rules whether the drug's use is "cruel and unusual" under the Eighth Amendment.

On a personal level, Holder admitted he has always opposed the death penalty.

"It is one thing to put somebody in jail for an extended period of time, have some tests that you can do to determine that person was, in fact, innocent. There is no ability to correct a mistake where somebody has been executed," he explained. "That is, from my perspective, the ultimate nightmare."

Watch his statement here: