Juveniles who kill present a dilemma for legislatures and courts. By committing the ultimate offense, juvenile murderers frequently engender the same sense of outrage that accompanies similar crimes perpetrated by adults. At the same time, their age and level of development may suggest a reduced degree of culpability that should temper society’s usual retributive response. Policy makers have been caught between these two conflicting impulses, with the result that the U.S. Supreme Court increasingly has become the ultimate arbiter. This trend was evident again in the Court’s most recent term, as it considered two cases that addressed the constitutionality of imposing mandatory life sentences without the possibility of parole on juvenile murderers.

The cases that brought the issue to the Supreme Court were Miller v. Alabama and its companion case, Jackson v. Hobbs (1). Fourteen-year-old Evan Miller and a friend smoked marijuana and drank alcohol with an adult neighbor, then robbed him and beat him to death with a baseball bat. Kuntrell Jackson, also 14 years old, joined two older boys in a convenience store robbery in which the clerk was shot and killed by one of his accomplices. Both cases were tried in adult criminal courts, and both defendants were convicted of murder. Alabama and Arkansas, where the crimes were committed, have minimum mandatory sentences of life without parole for murder, and both boys were sentenced to spend the rest of their lives in prison. Each appealed, asking the Court to rule that juveniles who were convicted of homicide could not be sentenced to life without parole.

That any juveniles would be sentenced to life without parole highlights the changes in the juvenile justice system over the last half century. As a result of the “child saver” movement of the late 19th and early 20th centuries, juvenile offenders generally were dealt with in a court system separate from the one that adjudicated charges against adults (2). In principle, juvenile courts were more concerned with rehabilitation of the offender than with punishment, and procedures in juvenile courts for much of their history were a good deal less formal than those in criminal courts. Beginning in the 1960s, however, the U.S. Supreme Court in a series of landmark cases questioned whether juvenile courts were much less punitive in practice than their adult counterparts. As a consequence, the justices required increased procedural protections for juveniles, including the rights to legal representation, notification of the charges, confrontation of accusers, avoidance of self-incrimination, and proof of guilt beyond a reasonable doubt (3,4).

Despite the Supreme Court’s doubts about whether juvenile courts were living up to their benevolent ideals, the juvenile system still differed significantly from adult courts in one important respect: the term of confinement that could be imposed ended when the juvenile turned 21 years old (5). Although the possibility always had existed of transferring juveniles who committed more heinous crimes to adult courts, the discretion to do so resided in the hands of juvenile court judges themselves and was exercised sparingly (5). However, in the 1980s and 1990s, a growing number of states amended their laws to mandate transfer to adult court for certain offenses or to give prosecutors the option of filing charges in adult court without prior judicial review (6). Along with transfer to adult criminal proceedings came susceptibility to the same punishments to which adults are subject, including prolonged sentences of confinement, up to and including life in prison, and the death penalty. Indeed, it was the imposition of the death penalty for crimes committed by juveniles that first drew the U.S. Supreme Court into this arena.

In Thompson v. Oklahoma in 1988, the Supreme Court ruled that a death sentence for a crime committed when an offender was less than 16 years old constituted cruel and unusual punishment and was thus precluded by the Eighth Amendment to the Constitution (7). The Court relied on the consensus among states that had established a minimum age for capital punishment (Oklahoma had not) that 16-year-olds were the youngest defendants who could be sentenced to death and noted that younger offenders had not been executed for at least 40 years. The Court also commented that “inexperience, less education, and less intelligence make the teenager less able to evaluate the consequences of his or her conduct, while, at the same time, he or she is much more apt to be motivated by mere emotion or peer pressure than is an adult.” However, a year later, the Court declined to extend its holding in Thompson to offenders who were 16 or 17 at the time of the crime, allowing them to continue to be sentenced to death (8).

By 2005, however, the Court’s view had changed, and in Roper v. Simmons the justices found that death sentences for all persons under the age of 18 at the time of their offense were unconstitutional (9). What had happened in the intervening 16 years? The majority noted both that execution of offenders for crimes committed when they were 16 or 17 had been rare and that five states had abolished the death penalty for juveniles since 1989. Hence, the Court looked to “the evolving standards of decency that mark the progress of a maturing society” to conclude that execution was no longer an acceptable punishment for juvenile offenses. In addition, it cited evidence of juveniles’ greater impulsivity and vulnerability to peer pressure and noted that their character tended to be less well formed compared with adults. With regard to character, the Court took notice that DSM-IV precluded the diagnosis of antisocial personality disorder below the age of 18 precisely because of the fluidity of character structure in adolescents.

Just five years after Roper, in Graham v. Florida, the justices turned their attention to other severe sentences imposed on juveniles, specifically exploring whether juveniles could be sentenced to life without parole for crimes other than homicide (10). Graham had been convicted in adult court of an armed robbery with assault and battery, committed when he was 16 years old, and he was initially placed on probation. However, after several additional offenses and probation violations, the trial judge concluded that he was incorrigible and sentenced him to life in prison. Florida had abolished parole for newly convicted offenders, leaving Graham with executive clemency as his only option for ultimate release. Graham asked the Court to extend its reasoning in Roper beyond the death penalty, and in its analysis the Court took up the invitation. The majority opinion reiterated the Court’s previous conclusions about the developmental immaturity of juveniles, and relying on briefs written by the American Medical Association and the American Psychological Association, noted in addition that “developments in psychology and brain science continue to show fundamental differences between juvenile and adult minds.” On that basis, the Court struck down Graham’s sentence as a violation of the Eighth Amendment but explicitly did not reach the question of whether life without parole might be acceptable for juveniles who murder.

As the pace of litigation quickened, it took only two years after Graham for the question of life without parole for juvenile murderers to reach the Court in the persons of Evan Miller and Kuntrell Jackson. Justice Kagan wrote the majority opinion in the combined cases, joined by the three other liberal justices and Justice Kennedy, the Court’s swing vote. The majority noted two lines of relevant precedent. The first, including Roper and Graham, had “adopted categorical bans on sentencing practices based on mismatches between the culpability of a class of offenders and the severity of a penalty.” A second set of cases had struck down mandatory imposition of the death penalty on the grounds that defendants were entitled to have potentially mitigating circumstances considered, including (pre-Roper) “the mitigating circumstances of youth.”

Applying Roper and Graham, the Court once more invoked the reduced culpability of juveniles, noting the by-now familiar triad of impulsivity, susceptibility to peer pressure, and character traits in flux. Justice Kagan also argued that the deterrent effect of harsh sentences was reduced for juveniles, because they were less likely to consider the consequences of their actions, again recruiting the empirical literature on adolescent development for support. Moreover, she held, the sentence of life without parole, which guaranteed that the juvenile would die in prison, was similar enough to the death penalty that the cases banning mandatory death sentences came into play as well. “Such mandatory penalties,” wrote Justice Kagan, “by their nature, preclude a sentencer from taking account of an offender’s age and the wealth of characteristics and circumstances attendant to it.”

However, in contrast to Graham, in which the Court categorically blocked the imposition of a sentence of life without parole in nonhomicide cases, here the Court struck down only mandatory use of these sentences. The majority held that this conclusion was sufficient to deal with the cases before the Court and that it did not have to reach the question of whether all juvenile life-without-parole sentences were constitutionally infirm. As an indication of the majority’s view on the subject, though, Justice Kagan added the following comment, “[G]iven all we have said in Roper, Graham, and this decision about children’s diminished culpability and heightened capacity for change, we think appropriate occasions for sentencing juveniles to this harshest possible penalty will be uncommon. . . . Although we do not foreclose a sentencer’s ability to make that judgment in homicide cases, we require it to take into account how children are different, and how those differences counsel against irrevocably sentencing them to a lifetime in prison.”

In their separate concurring opinion, Justices Breyer and Sotomayor indicated that they would go a step further, with particular relevance to the circumstances of Kuntrell Jackson’s case. These two justices would bar life without parole for juvenile offenders “who did not kill or intend to kill,” even if they were involved in a crime in which a killing occurred. On the other hand, there were also three dissenting opinions, coauthored by overlapping sets of the four conservative justices. Taken as a group, they challenged the relevance of the precedents relied on by the majority and objected to classifying as “cruel and unusual” sentences that had been authorized in a large majority of states and had recently been imposed on several thousand offenders. However, with Justice Kennedy again in the majority, as he was in Roper and Graham, the conservative justices once more came up at least one vote short.

Whereas some U.S. Supreme Court decisions appear to close the book on the issue in contention, Miller at best seems to represent an unstable equilibrium in the development of the Court’s reasoning on punishment of juveniles—and perhaps adults. Justice Kagan marshaled a battery of arguments against life-without-parole sentences for juveniles but ultimately allowed their use as long as they are not mandatory. The apparent contradiction did not escape the notice of Justice Alito in dissent, “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.”

Nor, given the logic of Miller and its forebears, should their rationale be limited to sentences of death and life without parole. If the malleability of juvenile character speaks against sentences that would preclude an adolescent from ever rejoining society, why does the same argument not apply to extremely lengthy sentences? Do the reduced culpability and possibility of change inherent in adolescence not militate equally powerfully against sentences of 40 or 50 years in prison, arguably the functional equivalent of a life sentence, especially in a state like Florida where parole is not an option (11)? Indeed, similar arguments could be envisioned regarding adults with sentences of many decades to life without possibility of parole, since adults too are capable of change. How far the Supreme Court is willing to go in this direction is unclear, but it is inconceivable that the appellate defense bar will not test the limits of this line of cases.

More fundamentally, as Chief Justice Roberts noted in his dissent, Miller represents a challenge to the dominant ethos in sentencing policy since the last quarter of the 20th century. “For most of the 20th century, American sentencing practices emphasized rehabilitation of the offender and the availability of parole. But by the 1980’s, outcry against repeat offenders, broad disaffection with the rehabilitative model, and other factors led many legislatures to reduce or eliminate the possibility of parole, imposing longer sentences in order to punish criminals and prevent them from committing more crimes.” By emphasizing the rehabilitative potential of juvenile offenders, the Court’s decision in Miller appears to nudge sentencing of juveniles back toward an older ideal, one that motivated the founding of the juvenile justice system in the first place. With rehabilitative goals reinstated, it may prove difficult to restrict their impact to the juvenile system, since many of the same arguments regarding rehabilitative potential can be offered for adults as well.

Thus Miller is a way station on the Court’s road to an uncertain endpoint in the constitutionalization of sentencing policy. Should the balance of the Court tip with future appointments in a more conservative direction, the rational of Miller may well be repudiated or at least not carried to its logical conclusion. At the moment, though, Miller represents an invitation to advocates to attempt to induce the Court to extend its rationale and impose additional constitutional limitations on sentencing options.

The author reports no competing interests.