Alabama's lethal injection chamber at Holman Correctional Facility in Atmore, Ala., is shown on Oct. 7, 2002.
Dave Martin, AP

MONTGOMERY, Ala. — The Alabama Legislature delivered a bill to the governor Wednesday that will allow condemned inmates to choose execution by nitrogen.

GOP Gov. Kay Ivey has not said whether she will sign the measure, which calls this method of capital punishment execution by nitrogen hypoxia. Her spokesman, Daniel Sparkman, said Tuesday that she would review it before making her decision; she has to make a decision by March 28 or the bill will become law without her signature.

If it becomes law, it would be effective June 1, and Alabama would be the third state to allow the method:

• Oklahoma, which has not executed anyone in three years, plans to use nitrogen hypoxia as its primary method.

• Mississippi, which once used the gas chamber in executions, offers nitrogen hypoxia as an alternative.

No state has carried out an execution using nitrogen gas, according to the Death Penalty Information Center.

Nitrogen hypoxia involves removing oxygen from the atmosphere around a condemned inmate though it is unclear how such an execution would be carried out. Supporters have suggested methods ranging from a sealed chamber to a mask placed on a condemned inmate secured in a chair.

► March 21: Death sentence reinstated for Mississippi's only woman on death row
► March 15: Oklahoma says it plans to use nitrogen for executions
► December 2015: Death sentences, executions plummeted in 2015

Senate Bill 272, sponsored by GOP state Sen. Trip Pittman of Montrose, Ala., passed the Alabama House in a 75-23 vote Tuesday after a very brief floor debate.

GOP Rep. Jim Hill of Moody, Ala., who handled the bill in the House, suggested that its use in assisted suicide showed it could lead to a peaceful death. 

“There is no evidence that indicated substantial physical discomfort,” he said.

In animal euthanasia, the American Veterinary Medical Association recommends the use of nitrogen hypoxia only on small creatures like birds and says larger animals should get a sedative if they face nitrogen hypoxia.

Alabama has used lethal injection as its primary method of execution since 2002 and that would remain the default method of execution. To die by nitrogen, a condemned inmate would have to send written notice to a warden after the Alabama Supreme Court upheld the inmate's death sentence. 

Like other states, Alabama has encountered challenges securing the drugs used in lethal injection. Many manufacturers have withdrawn drugs used in executions or protested over their products use in capital punishment.

The state also faces legal battles over the use of sedative midazolam, which has been present in botched executions around the country.

The Alabama Department of Corrections referred questions Tuesday to the Alabama Attorney General's office. A message seeking comment was sent to the attorney general's office Tuesday evening and was not returned.

► September 2015: Courts, states put death penalty on life support
► June 2015: Supreme Court refuses to ban controversial method of execution

The bill states that execution by nitrogen would become the state’s primary method of capital punishment if lethal injection “is declared unconstitutional or otherwise becomes unavailable.”

Rep. Laura Hall, a  Democrat from Huntsville, Ala., called nitrogen hypoxia “basically suffocating.” Hypoxia is the medical term for low oxygen in the bloodstream and bodily tissues, which can result in organ damage and eventual death.

► March 2015: Pharmacists' group opposes execution drugs
► November 2014: Utah revives plan for executions by firing squad

“What’s going to make this (method) better than the other ones we have?” Hall asked Hill.

“I can’t answer that better than you can, Ms. Hall,” Hill said. 

Contributing: The Associated Press. Follow Brian Lyman on Twitter: @lyman_brian

Alabama Senate Bill 272