One quick addendum to my previous commentary on this week’s decision in Graham v. Florida the use of foreign law by U.S. courts: Toward the very end of Justice Kennedy’s majority opinion, in part D where he gratuitously nods to world opinion about juvenile life-without-parole (LWOP) sentences, he takes issue with one of the lesser arguments we make in our brief, that no international treaty prohibits such sentences. (See page 31 of the Graham opinion — note that Cato itself is not mentioned because we were one of 13 groups signing the brief — and pages 14–16 of our brief.) Kennedy says that the issue of whether international law prohibits the United States from imposing the juvenile LWOP sentences is beside the point, that the proper question to ask is whether such sentences are “cruel and unusual.”

Well, yes, that’s the correct standard under the Eighth Amendment, and I’m glad that Justice Kennedy did not side with opposing amici and those in the legal academy who argue that various international conventions (or customary international law) do require such a prohibition. But Kennedy’s point here raises a further question: why is what someone in France or Japan or Brazil or Saudi Arabia says on the matter relevant to what is cruel and unusual under U.S. law?