One point I forgot to make

about the Supreme Court’s decision in the juvenile death penalty case. When the Court looks to European standards on these sorts of issues, it is not looking to any meaningful societal consensus. The abolition of the death penalty in Europe generally occurred in the face of public opinion that favored the penalty, and (based on the polls I’ve seen) probably still does. And it’s doubtful that decisions to ratify international covenants on the subject involve much public consideration either.
Thus, when our robed masters find confirmation in Europe of their views about what is decent and what is “cruel and unusual,” they are relying on the views of a very narrow segment of European opinion — essentially the prejudices of the folks with whom they schmooze on their summer junkets to the continent.