ATMORE, Alabama — The U.S. Supreme Court ruled Thursday that Alabama can proceed with using nitrogen gas to put a man to death, refusing to block what would be the nation’s first execution by a new method since 1982.

Alabama plans to put a face mask on 58-year-old Kenneth Eugene Smith and replace the air he is breathing with nitrogen to cause oxygen deprivation.

Smith’s lawyers have argued that the state is trying to make him the test subject for an untried execution method. The Alabama attorney general’s office said the execution method will render him unconscious within seconds and kill him within minutes

He is one of two men convicted in a 1988 murder-for-hire slaying of a preacher’s wife. The other was executed in 2010.