Alabama recently joined Oklahoma and Mississippi in authorizing executions by nitrogen gas, a method that has never been used before anywhere in the world.
Oklahoma was the first state to adopt a measure allowing the state to use nitrogen gas to execute people if lethal injection drugs cannot be obtained. After the botched execution of Clayton Lockett in 2014, Oklahoma halted executions. State representative Mike Christian reportedly saw a documentary about killing humans that included a segment on nitrogen inhalation, and he and two others with no scientific or medical knowledge presented a report on nitrogen to the state legislature, which held hearings on that report and then passed the bill. Governor Mary Fallin signed it into law in 2015.
Despite the absence of scientific evidence on executing people with nitrogen, Mississippi passed a similar law in 2017, and on March 22, 2018, Alabama Governor Kay Ivey signed legislation making Alabama the third state in the country to allow executions by nitrogen gas.
Nitrogen has killed people in industrial and medical accidents and in suicides. The gas itself is not poisonous but it kills by replacing oxygen.
Nitrogen is not used for terminal patients in states where medically assisted dying is legal. Dr. Charles D. Blanke, a medical oncologist and professor at Oregon Health and Science University who has studied data on physician-assisted dying, told the New York Times that pulmonary medicine and anesthesiology experts he consulted expressed concerns that carbon dioxide could build up and cause feelings of suffocation.
The American Veterinary Medical Association has declared that nitrogen gas is inappropriate for euthanizing animals. Its 2013 guidelines provide, "Current evidence indicates this method is unacceptable because animals may experience distressing side effects before loss of consciousness." Responses to the gas vary according to species; a 70-pound pig that inhaled nitrogen gas would take seven minutes to die.
There are different grades of nitrogen, with different purities and regulations; observers would need protection, and nitrogen would have to be cleared from the room before anyone could enter to declare death and remove the body.
"If and when states begin carrying out executions with nitrogen, it will amount to the same type of experimentation we see in the different variations of lethal injection," said Jen Moreno, a lawyer who is an expert on lethal injection at the Berkeley Law Death Penalty Clinic, told the New York Times.