Justice Kennedy's fiat.

JUSTICE ANTHONY KENNEDY, writing for a 5-4 majority of the Supreme Court, declared it unconstitutional to execute people for crimes committed when they were under 18. Our "evolving standards of decency" supposedly forbid such executions.

Now it is certainly possible that a criminal might be too young to be considered fully culpable for his actions. Justice Kennedy cited studies showing that many minors display a "lack of maturity." (For this we need studies?) Figuring out whether a particular criminal was mature enough to deserve severe punishment can be tricky. That's why we have juries. Jurors are certainly capable of weighing a defendant's age as they deliberate over whether to impose the death penalty. Eighteen states have decided that it would be better to impose a blanket rule that minors will not be executed. One can think of good arguments for or against such a rule. That's why we have state legislatures: to decide such questions.

Justice Kennedy decided, however, that the 18 states that bar capital punishment for young murderers, and the 12 that bar capital punishment altogether, added up to a "national consensus" against executing the young. Having invented this "consensus," Kennedy then declared that it was unconstitutional for 20 states to continue to fall outside it. In support of his reasoning--if that's the word for it--he cited the "overwhelming weight of international opinion against the juvenile death penalty." He mentions two international conventions. The fact that the United States did not ratify one of them, and ratified another with the qualification that it retained the right to impose the juvenile death penalty, counted for nothing with Kennedy.

We do not believe that foreigners' opinion about any topic tells us anything about what the Constitution says about that topic. But the problem with Kennedy's opinion is not that it gives too much weight to foreign opinion. As Judge Bork notes (page 17), Kennedy is merely using foreign opinion to bolster a result he favors. The fact that most countries reject third-trimester abortion is not causing the Court to rethink its abortion jurisprudence. Since European governments reject capital punishment altogether, doesn't Kennedy have the premises in place to declare it unconstitutional? Such a ruling, however, would risk a public backlash. As much as Kennedy wants to show the world how much his "standards of decency" have "evolved," he does not want to take that risk. So Justice Kennedy and his majority are not declaring the death penalty unconstitutional. Yet.