Lawyers for Mr. Smith are likely to object to this human experiment on the basis that it violates the Eighth Amendment’s proscription against “cruel and unusual punishments.” It is true that Mr. Smith’s lawyers appealed to the court for this method of execution. But that was only because of the twisted logic of the U.S. Supreme Court’s death penalty jurisprudence, under which condemned prisoners must plead for their preferred alternative method of putting someone to death — and which Mr. Smith’s lawyers did after the nightmare of his failed lethal injection execution. He invoked nitrogen, the alternative available under Alabama statutes, a method the state enacted in March 2018 after the Hamm execution fiasco. But under the Supreme Court’s guidelines, the alternative must be not only “feasible” and “readily implemented,” but also one that “significantly reduces a substantial risk” of suffering.

Under the Eighth Amendment, execution by nitrogen is surely unusual because it has never been used as a method of execution in this country or elsewhere, as far as we know. It is also likely to cause needless agony and suffering in the execution chamber. Plus, the threat of a second attempt at execution under circumstances of human experimentation is unconscionably cruel.

The recent track record in the federal courts is not comforting, though. The conservative supermajority at the Supreme Court, especially, has recently been lifting stays of execution imposed by the lower federal courts at a frightening pace, in unsigned opinions, without explanation. Their inexplicable behavior in death penalty cases has given rise to an alarming shadow docket. Some of the justices have become, if anything, the nation’s executioners.

Of course, that does not mean we can throw up our hands. Moments like these present an opportunity for the justices to step up and lead the country to a higher plane — to what the court, in its Eighth Amendment rulings, has so often called “the evolving standards of decency that mark the progress of a maturing society.” It is often at junctures like these that righteous magistrates come forward to resist inhumanity — like the Portuguese consul general in Bordeaux, France, Aristides de Sousa Mendes, who defied expectations and issued visas for refugees fleeing the country in June 1940, saving thousands of lives.

Let us hope that the justices exercise their license to practice in the ways exemplified by Sousa Mendes. Let us hope they demonstrate cleareyed analysis and prevent this human experimentation. In the meantime, it will fall on the rest of us to show the world that this is not what we stand for.

Bernard E. Harcourt is a professor of law and political theory at Columbia. He began his legal career representing people on Alabama’s death row and continues to represent people sentenced to death and life imprisonment without parole. He is the author, most recently, of “Cooperation: A Political, Economic, and Social Theory.”