Alabama is preparing to execute an inmate for the shooting deaths of three people during a 1994 robbery despite objections from the man’s lawyers that the state’s method of execution is unconstitutional and violates the eighth amendment.

Robert Bryant Melson, 46, is scheduled to die by lethal injection on Thursday evening at a south Alabama prison. If the execution goes ahead, it will be the 13th this year in the United States and the second in Alabama in 2017.

State prosecutors said Melson and another man who used to work at the restaurant robbed a Popeye’s in Gadsden, 60 miles north-east of Birmingham. They said Melson opened fire on four employees in the restaurant’s freezer. Nathaniel Baker, Tamika Collins and Darrell Collier were killed.

The surviving employee, Bryant Archer, crawled for help and was able to identify one of the robbers as the former worker. While he could not identify Melson, prosecutors said Melson told police he had been with the former employee that night. A shoeprint behind the store matched Melson’s shoes, they said.

Lawyers for Melson tried to halt his execution, arguing that a drug used in the state’s lethal injection has been linked to troubled executions in Alabama, Arizona and Oklahoma, where inmates could be seen twisting on death chamber gurneys. Lawyers said its use violated protections against cruel and unusual punishment.

Midazolam is supposed to prevent inmates from feeling pain before other drugs are given to stop their lungs and heart, but several executions in which inmates lurched or coughed have raised questions about its use. An inmate in Alabama coughed and heaved for the first 13 minutes of an execution held in December.

Melson’s attorneys wrote in the filing to the Alabama supreme court: “Alabama’s execution protocol is an illusion. It creates the illusion of a peaceful death when in truth, it is anything but. It should not allow Mr Melson’s execution to go forward in the face of botched executions and significant challenges to the constitutionality of Alabama’s execution protocol.”



Last week, a federal appeals court in Atlanta issued a stay of execution for Melson because of the drug issue.



But Alabama appealed and the US supreme court on Tuesday lifted Melson’s stay, allowing the execution to proceed on Thursday.

“If a stay were granted, Melson’s execution would be delayed many months, if not years. The state, the victims’ families, and the surviving victim in this case have waited long enough for justice to be delivered,” the attorney general’s office wrote in a Wednesday court filing with the 11th circuit.