Alabama is looking to become the first state to ever execute a prisoner by forcing them to breathe pure nitrogen. On Friday, a court filing from the Alabama attorney general’s office indicated that it wanted to put Kenneth Eugene Smith, 58, to death by nitrogen hypoxia—which deprives inmates of oxygen and suffocates them. Although this method is touted as more “humane,” Scientific American reported that there is little evidence showing how long the process takes or how much a person might suffer. Only three states have authorized the use of nitrogen hypoxia for execution—Alabama, Oklahoma, and Mississippi—but none have used it yet to carry out a death sentence. Smith was convicted 1988 for a murder-for-hire killing of a preacher’s wife and was set to be executed last year by lethal injection, but it was botched due to issues of inserting an IV into his veins. “No state in the country has executed a person using nitrogen hypoxia and Alabama is in no position to experiment with a completely unproven and unused method for executing someone,” the Equal Justice Initiative told the Associated Press.