Justice Sotomayor: Lethal Injection May Be 'Our Most Cruel Experiment Yet'

Supreme Court Justice Sonia Sotomayor wrote Tuesday that lethal injection "may turn out to be our most cruel experiment yet" in the effort to find a humane way to carry out the death penalty, The Washington Post reported.

The opinion came in a dissent, along with Justice Stephen Breyer, from the high court's decision not to hear the case of Alabama's oldest inmate, Thomas Arthur, who's on death row for the 1982 murder of his girlfriend's husband.

The majority didn't give a reason for passing up the case.

Sotomayor has become an outspoken critic of how the death penalty is carried out, the Post reports, and referring to current methods — hanging, electrocution, the gas chamber and lethal injection — she said:

"Evolving standards have yielded a familiar cycle: States develop a method of execution, which is generally accepted for a time. Science then reveals that — unknown to the previous generation — the states' chosen method of execution causes unconstitutional levels of suffering."

Lethal injection, she said, may be the latest in that pattern.

"What cruel irony that the method that appears most humane may turn out to be our most cruel experiment yet," she wrote, the Post reported.

"Like a hangman's poorly tied noose or a malfunctioning electric chair, midazolam might render our latest method of execution too much for our conscience — and the Constitution — to bear," Sotomayor wrote, according to AL.com.

In the Arthur case, he'd objected to the use of the drug midazolam in his planned lethal injection, saying it has led to unconstitutional levels of pain and suffering in previous executions.

The Supreme Court upheld the drug's use in 2015, arguing inmates who objected to it must prove it would cause severe pain and propose another means of execution.

Arthur proposed a firing squad.

But the U.S. Court of Appeals for the 11th Circuit turned him down, saying he hadn't met the burden of proving midazolam would cause pain so severe it would be unconstitutional — and that Alabama didn't sanction firing squads.

Sotomayor called the 2015 Supreme Court decision's test "a macabre challenge" but argued Arthur had met it.

"After 34 years of legal challenges, Arthur has accepted that he will die for his crimes," she wrote. "He now challenges only how the state will be permitted to kill him."

• Court Considers Constitutionality of Ohio Execution Process
• Mississippi Firing Squad Considered as Method of Execution