Under the Supremacy Clause of the Constitution, state collateral review courts have no greater power than federal habeas courts to mandate that a prisoner continue to suffer punishment barred by the Constitution. If a state collateral proceeding is open to a claim controlled by federal law, the state court “has a duty to grant the relief that federal law requires.” Yates, 484 U. S., at 218. Where state collateral review proceedings permit prisoners to challenge the lawfulness of their confinement, States cannot refuse to give retroactive effect to a substantive constitutional right that determines the outcome of that challenge.
As a corollary to a child’s lesser culpability, Miller recognized that “the distinctive attributes of youth diminish the penological justifications” for imposing life without parole on juvenile offenders. 567 U. S., at ___ (slip op., at 9). Because retribution “relates to an offender’s blameworthiness, the case for retribution is not as strong with a minor as with an adult.” Ibid. (quoting Graham, supra, at 71; internal quotation marks omitted). The deterrence rationale likewise does not suffice, since “the same characteristics that render juveniles less culpable than adults— their immaturity, recklessness, and impetuosity—make them less likely to consider potential punishment.” 567 U. S., at ___–___ (slip op., at 9–10) (internal quotation marks omitted). The need for incapacitation is lessened, too, because ordinary adolescent development diminishes the likelihood that a juvenile offender “‘forever will be a danger to society.’” Id., at ___ (slip op., at 10) (quoting Graham, 560 U. S., at 72). Rehabilitation is not a satisfactory rationale, either. Rehabilitation cannot justify the sentence, as life without parole “forswears altogether the rehabilitative ideal.” 567 U. S., at ___ (slip op., at 10) (quoting Graham, supra, at 74).
The Court now holds that Miller announced a substantive rule of constitutional law. The conclusion that Miller states a substantive rule comports with the principles that informed Teague. Teague sought to balance the important goals of finality and comity with the liberty interests of those imprisoned pursuant to rules later deemed unconstitutional. Miller’s conclusion that the sentence of life without parole is disproportionate for the vast majority of juvenile offenders raises a grave risk that many are being held in violation of the Constitution.
Giving Miller retroactive effect, moreover, does not require States to relitigate sentences, let alone convictions, in every case where a juvenile offender received mandatory life without parole. A State may remedy a Miller violation by permitting juvenile homicide offenders to be considered for parole, rather than by resentencing them. See, e.g., Wyo. Stat. Ann. §6–10–301(c) (2013) (juvenile homicide offenders eligible for parole after 25 years). Allowing those offenders to be considered for parole ensures that juveniles whose crimes reflected only transient immaturity—and who have since matured—will not be forced to serve a disproportionate sentence in violation of the Eighth Amendment. Extending parole eligibility to juvenile offenders does not impose an onerous burden on the States, nor does it disturb the finality of state convictions. Those prisoners who have shown an inability to reform will continue to serve life sentences. The opportunity for release will be afforded to those who demonstrate the truth of Miller’s central intuition—that children who commit even heinous crimes are capable of change.
Read the entire Opinion here - Montgomery vs Louisiana