A federal judge on Tuesday permanently blocked Alabama from executing a man with nitrogen gas after declaring the method violates the ban on cruel and unusual punishment. Alabama became the first state in the nation to use the execution method in January 2024, but has faced repeated legal challenges to its use.

Emily C Marks, a US district judge, permanently enjoined the state from executing Jeffery Lee by nitrogen gas. Lee was scheduled to be executed Thursday at an Alabama prison.

A spokesman for Alabama attorney general Steve Marshall said the state is appealing the decision. The case will likely end up before the US supreme court, which has previously let nitrogen executions proceed.

In 2000, a jury sentenced Lee to life without parole for the 1998 murders of Jimmy Ellis and Elaine Thompson. A judge later declined to follow the jury’s recommendation and sentenced Lee to death. In 2017, Kay Ivey, an Alabama governor, signed a bill to ban such cases of judicial override, but the law only applied to future – and not past – cases. Lee’s attorneys have since asked Ivey to grant him clemency and end judicial override retroactively.

The case continued in court until last month on 29 May, when Marks ruled that Alabama could execute Lee using nitrogen gas, citing testimony from three medical experts that “air hunger” induced by such an execution did not amount to an unconstitutional level of pain.

“For Eighth Amendment purposes, the anxiety evoked by air hunger – lasting not significantly more than one to three minutes – is more an ‘inescapable consequence of death,’ than ‘superadded’ pain well beyond what’s needed to effectuate a death sentence,” Marks wrote.

Days later, on 8 June, a three judge panel of 11th circuit court of appeals judges reversed Marks’ order, writing: “Alabama’s nitrogen hypoxia protocol presents a ‘substantial risk of serious harm’ – severe pain over and above death itself’”. The appeals court ordered Marks to consider whether Lee could be executed by his preferred method of firing squad instead.

On Tuesday, Marks issued a 26-page ruling, writing that litigation is a constant in death penalty cases and that the state of Alabama can pursue two other authorized execution methods: lethal injection and the electric chair. She said Lee is “not entitled to an injunction barring the state from executing him using one of those methods …”

“Were Alabama to adopt firing squad as a method of execution, that method would likely be challenged as well. Indeed, there is likely no method – no matter how humane – that would be immune to constitutional challenge. But the constitution does not guarantee a painless death, and human life cannot be purposefully extinguished without some risk of pain. The court, the condemned, and the state must all confront that sobering reality,” Marks wrote.

Reports of the extreme pain induced by “nitrogen hypoxia” emerged after the first such execution occurred in the US in 2024. Kenneth Eugene Smith’s execution by nitrogen gas took 22 minutes, and Lee Hedgepeth, a journalist who witnessed the execution, told the BBC’s Newsday programme: “I’ve been to four previous executions and I’ve never seen a condemned inmate thrash in the way that Kenneth Smith reacted to the nitrogen gas.”

A spokeswoman for Lee’s legal team said they did not have an immediate comment.