If Kenneth Eugene Smith is brought to the Alabama death chamber to face execution next week for his role in the 1988 murder-for-hire of a pastor’s wife, the state plans to use an untested and untried method to end his life, suffocating him with a stream of nitrogen gas to be delivered through a face mask.

In a federal appeals court Friday, Smith’s lawyers sought to block it, arguing that not only have Smith’s constitutional rights been violated, but that he could be subjected to an agonizing death and that most of the details surrounding the state’s new execution protocol “deserve more scrutiny.”

The use of nitrogen gas will be a capital punishment first, even though it has not only been denounced by some medical professionals but also by veterinarians who oppose its use on animals. In 2020, the American Veterinary Medical Association advised against the use of nitrogen gas as a way to euthanize most mammals, calling it “distressing.” One of the few uses of nitrogen gas in animal euthanasia is with chickens.

The United Nations’ Office of The High Commissioner for Human Rights has expressed alarm, saying in a statement that the untested method “could amount to torture or other cruel, inhuman or degrading treatment or punishment under international human rights law.”