WASHINGTON — The Supreme Court on Monday rejected Alabama’s offer to execute a death row inmate by lethal injection despite a lower court ruling that his preference for lethal gas was a viable alternative method.

The court’s decision not to accept the state’s case leaves the lower court’s ruling standing.

Kenneth Smith, sentenced to death for murdering Elizabeth Sennett in 1988, opposed being executed by lethal injection because of the pain it would cause him. He alleged that he would violate his right to be free from cruel and unusual punishment under the Eighth Amendment to the Constitution.

A lethal injection chamber in Alabama.File Dave Martin / AP

Smith suggested that lethal gas (nitrogen hypoxia) be used instead.

The Atlanta-based US Court of Appeals for the 11th Circuit ruled in favor of Smith in November, saying that because the state approved the use of lethal gas, Smith could seek an alternative method of execution.

The appeals court ruling was issued the same day the state unsuccessfully tried to execute Smith by lethal injection. Officials called off the execution after struggling to insert an IV before the death sentence expired at midnight. The Supreme Court, which allows executions to take place regularly, had previously allowed the execution to take place.

Conservative Justices Clarence Thomas and Samuel Alito said they would have ruled in favor of the state.

«When the question is whether the Eighth Amendment requires a state to replace its chosen method with an alternative method of executing the plaintiff, it is simply irrelevant, without more, that the state’s statutes authorize the use of the alternative method to be carried out.» . sometime in the indefinite future,» Thomas wrote.

Alabama officials say that while the deadly gas was approved as a method of execution in 2018, an execution protocol has not been finalized. He gave inmates 30 days to choose an alternate method, an option Smith did not choose at the time, the state says.

Smith’s lawyers say the state is already planning to execute other death row inmates using lethal gas.

The case follows a 2015 Supreme Court ruling that rejected a challenge to the lethal injection protocol used by Oklahoma.

The court then made it clear that if an inmate wants to challenge the method of execution, he must show that there is a feasible alternative that can be easily implemented.

In a follow-up case in 2019, the court ruled against a convicted murderer in Missouri who sought to die with lethal gas rather than lethal injection because of a rare medical condition, saying prisoners were not guaranteed «a death without pain».

Death penalty advocates have been critical of lawyers making last-minute claims in an effort to delay executions. During oral argument in the 2015 case, conservative Justice Samuel Alito referred to it as «guerrilla warfare against the death penalty.»

Has been nine executions in the United States so far this year, according to the Death Penalty Information Center.