The Supreme Court is giving the green light for Alabama to conduct the nation’s first-ever execution by nitrogen gas, rejecting arguments that the new, untested method constitutes cruel and unusual punishment under the Eighth Amendment to the Constitution.

On Wednesday, the high court rejected 58-year-old inmate Kenneth Eugene Smith’s request to stop his execution scheduled for Thursday. The brief order gave no reasons and had no noted dissents. Smith’s execution marks the inaugural use of  nitrogen gas inhalation, known as nitrogen hypoxia, as an alternative form of capital punishment to lethal injection. 

The decision marks the culmination of legal battles over Smith’s future. In May of 2023, the Supreme Court rejected Alabama’s bid to put Smith to death by lethal injection. It had previously allowed the method to be used on Smith, but in November of 2022, the Alabama authorities failed to conduct it successfully after struggling for hours to find a vein to administer the deadly drug to Smith. 

That botched execution prompted a new round of litigation over whether Alabama could instead execute Smith using nitrogen gas, a method which Smith himself initially suggested. Last week, Smith sought a preliminary injunction against Alabama’s protocol in a last-ditch effort to save his life. He has repeatedly denied the charge on which he was convicted in 1988 — that he killed Elizabeth Sennett in a murder-for-hire plot.

Nitrogen hypoxia has drawn heated opposition from some doctors and human rights advocates. “The Department of Corrections, in creating these new execution methods, is trying to resolve the problem of the nastiness of killing,” a professor of human rights at Birmingham City University, Jon Yorke, told the Sun. He co-authored a complaint regarding Smith to the United Nations.

The Supreme Court, however, has affirmed that capital punishment abides by the Constitution. In the 2008 Baze v. Rees decision, Chief Justice Roberts opined that states have the right to carry out capital punishment as it sees fit, so long as such punishment does not involve “unnecessary cruelty.”