Nitrogen Gas Approved as Backup Execution Method

Oklahoma Gov. Mary Fallin signed a bill on Friday that would allow the state to perform executions with nitrogen gas if lethal injection is ruled unconstitutional or becomes unavailable.
Fallin's office said in a press release that nitrogen causes a quick loss of consciousness and then death from lack of oxygen.
CNN affiliate KFOR says it's never been used in an execution in the United States.
Robert Dunham, executive director of the Death Penalty Information Center, told the Washington Post that the same "painless" argument had been used to advance the use of lethal injections.