Hey, kids! Wanna kill somebody?

Then the US Supreme Court has good news for you! If you're convicted of murder, not only can you not be given the death penalty, you can't even be given life in prison without parole:

Extending its ever-evolving, and ever less coherent, Eighth Amendment jurisprudence, the Supreme Court ruled today, by a 5-4 vote in Miller v. Alabama, that it is unconstitutional to establish a mandatory life-without-parole sentence for any category of murder committed by a person younger than 18 (otherwise known, if only in this context, as a “juvenile”). The Court’s ruling—majority opinion by Justice Kagan, joined by Kennedy, Ginsburg, Breyer, and Sotomayor—invalidated contrary aspects of sentencing regimes established by 28 States and the federal government.
The majority declined to address the argument that the Eighth Amendment requires a categorical bar on the discretionary imposition on a juvenile of life without parole, but it volunteered that “appropriate occasions for sentencing juveniles to this harshest possible penalty” (the death penalty already having been categorically deemed off limits) “will be uncommon.”

The emphasis is in Ed Whelan's original, but that distinction will not stand. Just watch. With Miller, SCOTUS continues down its road from the 8th Amendment prohibiting cruel and unusual punishment to the 8th Amendment prohibiting any punishment. Justice Alito's dissent is epic:

It is true that, at least for now, the Court apparently permits a trial judge to make an individualized decision that a particular minor convicted of murder should be sentenced to life without parole, but do not expect this possibility to last very long. The majority goes out of its way to express the view that the imposition of a sentence of life without parole on a “child” (i.e., a murderer under the age of 18) should be uncommon. Having held in Gra­ham that a trial judge with discretionary sentencing authority may not impose a sentence of life without parole on a minor who has committed a nonhomicide offense, the Justices in the majority may soon extend that holding to minors who commit murder. We will see.
What today’s decision shows is that our Eighth Amendment cases are no longer tied to any objective indicia of society’s standards. Our Eighth Amendment case law is now entirely inward looking. After entirely disregarding objective indicia of our society’s standards in Graham, the Court now extrapolates from Graham. Future cases may extrapolate from today’s holding, and this process may continue until the majority brings sentencing practices into line with whatever the majority views as truly evolved standards of decency.
The Eighth Amendment imposes certain limits on the sentences that may be imposed in criminal cases, but for the most part it leaves questions of sentencing policy to be determined by Congress and the state legislatures—and with good reason. Determining the length of imprisonment that is appropriate for a particular offense and a particular offender inevitably involves a balancing of interests. If imprisonment does nothing else, it removes the criminal from the general population and prevents him from committing additional crimes in the outside world. When a legislature prescribes that a category of killers must be sentenced to life imprisonment, the legislature, which presumably reflects the views of the electorate, is taking the position that the risk that these offenders will kill again outweighs any countervailing consideration, including reduced culpability due to immaturity or the possibility of rehabilitation. When the majority of this Court countermands that democratic decision, what the majority is saying is that members of society must be exposed to the risk that these convicted murderers, if released from custody, will murder again.
Unless our cases change course, we will continue to march toward some vision of evolutionary culmination that the Court has not yet disclosed. The Constitution does not authorize us to take the country on this journey.