SCOTUS declares unconstitutional juvenile death penalty in Roper

In a 5-4 decision authored by Justice Anthony Kennedy, the Supreme Court has held in Roper v. Simmons that the death penalty "is a disproportionate punishment for juveniles," and thus the Eighth Amendment prohibits the execution of a murderer who committed his crime before age 18.  Justice Kennedy's opinion for the Court is here, Justice Stevens' concurrence is here, Justice Scalia's dissent is here, and Justice O'Connor's dissent is here.  Another 80+ pages of SCOTUS wisdom for our reading pleasure.  SCOTUS Blog already has a brief report on the case here, and I hope to provide some additional commentary on this notable ruling soon.

UPDATE: The first part of Justice Kennedy's opinion for the Court closely tracks the Court's 2002 decision in Atkins prohibiting the execution of persons with mental retardation:

As in Atkins, the objective indicia of consensus in this case — the rejection of the juvenile death penalty in the majority of States; the infrequency of its use even where it remains on the books; and the consistency in the trend toward abolition of the practice — provide sufficient evidence that today our society views juveniles, in the words Atkins used respecting the mentally retarded, as "categorically less culpable than the average criminal." 536 U. S., at 316.

And Justice Kennedy's discussion of "theory" considerations also track Atkins and concludes with this interesting explanation of the Court's reversal of Stanford and its 1989 approval (per Justice Scalia) of the juvenile death penalty:

To the extent Stanford was based on review of the objective indicia of consensus that obtained in 1989, it suffices to note that those indicia have changed.  It should be observed, furthermore, that the Stanford Court should have considered those States that had abandoned the death penalty altogether as part of the consensus against the juvenile death penalty; a State’s decision to bar the death penalty altogether of necessity demonstrates a judgment that the death penalty is inappropriate for all offenders, including juveniles. Last, to the extent Stanford was based on a rejection of the idea that this Court is required to bring its independent judgment to bear on the proportionality of the death penalty for a particular class of crimes or offenders, it suffices to note that this rejection was inconsistent with prior Eighth Amendment decisions.  It is also inconsistent with the premises of our recent decision in Atkins.