United States Supreme Court Justice Anthony Kennedy, writing for a majority of the court which included Justices Stevens, Ginsberg, Breyer, and Sotomayor held on May 17, 2010 in Washington, D.C. that sentencing ajuvenile offender to life imprisonment without the possibility of parole for a nonhomicide crime violates the U.S. Constitution's prohibition of cruel and unusual punishment. Stevens wrote a concurrence that Ginsberg and Sotomayor joined. Chief Justice Roberts concurred in the result. Justice Thomas dissented, joined by Justice Scalia for all of his opinion and Justice Alito for Parts I and III. Alito also filed his own dissent.
Kennedy reasoned that to determine whether a punishment is cruel and unusual, courts must look to the evolving standards of decency that mark the progress of a maturing society. The Constitution's ban on cruel and unusual punishments requires that punishment for crime should be graduated and proportioned to the offense. SCOTUS has considered proportionality challenges two ways. In non-death-penalty case , the court has examined whether a term-of-years may be too long given all the circumstances in a particular .In death penalty cases, overruling some categories of punishment have been considered. This case is the first categorical proportion challenge in a noncapital case. That the Feds and many states allow life sentences for juvenile offenders doesn't address the immorality of this practice. Only the U.S. does this; other countries don't.
I had not known that Florida did not have parole. The Chief Justice's opinion pieces together a ruling in this case from prior decisions as opposed to the majority's building a new analytic framework. Stevens's opinion was a snippy attack on Thomas's.