Montgomery, Ala. — A federal judge ruled on Thursday that execution by nitrogen gas doesn't violate the constitutional ban on cruel and unusual punishment, rejecting an Alabama inmate's claim that it causes excessive suffering.

The ruling came after the first bench trial in the country to examine the constitutionality of the execution method that has now been used to put eight people to death, seven in Alabama and one in Louisiana. The ruling clears the way for Alabama and other states to continue with the method and is a setback for critics who hoped a fuller examination of Alabama's protocol would halt its use.

The execution method, first used in 2024, involves strapping a respirator to the person's face and replacing breathable air with pure nitrogen gas, causing death from lack of oxygen. The lawsuit challenging the method was filed last year by death row inmate Jeffery Lee. Lee, 58, is scheduled to be executed with nitrogen gas on June 11 at a south Alabama prison.

"While Lee establishes that death by nitrogen hypoxia involves some suffering, he fails to show that the protocol is cruel and unusual in violation of the Eighth Amendment," U.S. District Judge Emily C. Marks wrote.

Attorneys for the state and Lee disagreed on how long inmates are awake during a nitrogen gas execution. Marks wrote the evidence shows Alabama's protocol "likely causes severe air hunger -the most severe form of breathing discomfort - for one to three minutes" but did not arise to a constitutional violation.

Lee's attorneys indicated in court filings that they are appealing the decision.

The Alabama attorney general praised the judge's decision.

"After the first full trial on nitrogen hypoxia in the entire country, the district court found it to be constitutional. The district court considered all the evidence and concluded that nitrogen hypoxia is not cruel and unusual, affirming that the question of capital punishment belongs to the people and their representatives, not the courts, to resolve," Alabama Attorney General Steve Marshall said.

Inmates executed by nitrogen gas have displayed various levels of shaking during the executions, and lawyers for the state and inmates have disagreed on whether those are involuntary or a sign of suffering. Alabama's last nitrogen gas execution took more than 30 minutes to complete.

Marks noted that Lee faced a high legal bar because the U.S. Supreme Court has yet to find a state's method of execution qualifies as cruel and unusual.

Five states have authorized nitrogen gas as an execution method, according to the Death Penalty Information Center, although only two have used it.

Lee was convicted of capital murder for killing Ellis and Thompson on Dec. 12, 1998, near the small town of Orrville, Alabama. Prosecutors said Lee entered a pawn shop with a sawed-off shotgun and fatally shot Jimmy Ellis, the owner of the store, and Elaine Thompson, a store employee.

A jury voted 7-5 that Lee should receive a sentence of life imprisonment. However, a judge overrode that recommendation and sentenced Lee to death. Alabama in 2017 ended the practice of judicial override and no longer allows a judge to disregard a jury's sentencing decision in death penalty cases.

Lee's legal team didn't issue an immediate comment on the decision.

"The real torture of the death penalty is in the decades of waiting. With what we know about each of the available methods of being killed in Alabama or in the U.S., I can't imagine anyone choosing conscious suffocation," said Abraham Bonowitz, executive director of Death Penalty Action, a group that opposes the death penalty.

He added that Lee wouldn't face the death penalty if sentenced today because judicial override has been abolished.