The Supreme Court continues its “race to the bottom” on matters of criminal punishment. In Miller v. Alabama, a 5-4 majority used the cases of two minors convicted of murder to invalidate the rule of 28 states and the federal government, which prescribed a mandatory sentence of life-without-parole for all minors convicted of aggravated murder. The majority relied on the 2005 Roper decision, which invalidated the death penalty for minors, and the 2010 Graham decision, which invalidated life imprisonment without parole for minors convicted of non-homicide offenses. The majority contended that those cases “led to” the most recent decision.

As Chief Justice John Roberts’s dissent made clear, the past decisions did not compel the newest intrusion on legislative decision-making. Both Roper and Graham at least paid lip service to the theory that “death is different,” so that there could be limits on a state’s use of death as punishment, or its punishing offenses that did not cause death. Indeed, the Chief Justice blasted the “bait-and-switch.” The Roper Court found capital punishment unnecessary for juveniles because “the punishment of life imprisonment without possibility of parole is itself a severe sanction.” In other words, although Roper expressly recognized the deterrent value of life-without-parole for juveniles and condoned its imposition, the Court now cites Roper as absolutely barring that sentence. Now that the Court has held the limitations imposed by the Eighth Amendment are due not to the fact that “death is different,” but that “children are different,” and must receive a sentencing “discount” compared to adults, there is no logical stopping point until the Court forbids ever sentencing a minor.

Justice Elena Kagan, the author of this week’s opinion, abandoned the pretense that the Court won’t restrict punishments any further. She “predicts” that although some defendants may still receive a life-without-parole sentence, the punishment will become “uncommon.” The Chief Justice correctly observed this prophesy will be self-fulfilling; once the sentence becomes “unusual,” the majority will hold that it violates the Eighth Amendment.

Although Roberts’s legal analysis is flawless, he shines best in his philosophical response to the mantra that deference to “evolving standards of decency” always compels reductions of punishment. “Mercy towards the guilty can be a form of decency,” he wrote, “and a maturing society may abandon harsh punishments that it comes to view as unnecessary or unjust. But decency is not the same as leniency. A decent society protects the innocent from violence. A mature society may determine that this requires removing those guilty of the most heinous murders from its midst, both as protection for its other members and as a concrete expression of its standards of decency. As judges we have no basis for deciding that progress toward greater decency can move only in the direction of easing sanctions on the guilty.”

Whether greater decency may involve maximizing justice as well as mercy may become the defining criminal law question for the next generation.