The Roberts Court's Liberal Turn on Juvenile Justice THE Supreme Court's decision this week to ban mandatory life sentences without the possibility of parole for offenders younger than 18 is an emphatic rejection of the "get tough" juvenile justice policies of the 1980s and 1990s, which punished children as if they were adults. Writing for the majority, Justice Elena Kagan's clear statement not only recognized the political and biological principle that children are different from adults but at last also inscribed it into constitutional law. Treating children differently from adults may be a radical idea, but it's also an old one, predating the American Revolution. The political philosopher John Locke argued that children's lack of reasoning capacity, which disqualified them from participating in government, also made them less culpable for their criminal acts. By the turn of the 20th century, progressive child advocates embedded the principle that children are different from adults - and thus require individualized handling of their cases - into the foundation of the world's first juvenile courts. Today, all 50 states and the District of Columbia have juvenile justice systems that divert youthful offenders from the criminal justice system at large. In the 1980s and 1990s, though, in response to mounting concerns about juvenile crime, many states changed their laws to give prosecutors, instead of juvenile court judges, the authority to determine which court system would handle a particular child's case. As a result, prosecutors now make the vast majority of decisions to transfer juveniles to criminal court. This dramatic departure from past practices threatened to undermine the longstanding principle that children's cases should not be handled like those of adults. By the late "90s, some critics even called for the abolition of the juvenile court. In the past, juvenile court judges were faced with many difficult cases involving adolescents who committed serious and violent offenses. A small percentage of these young offenders were transferred to criminal court; in fact, the Supreme Court's first juvenile justice decision, Kent v. the United States, in 1966, addressed such a case. If Morris Kent Jr., a 16-year-old boy accused of rape and robbery, had remained in the juvenile justice system, he would have received no more than five years of treatment or punishment. If he were moved to criminal court and tried as an adult, however, he would have faced the possibility of the death sentence. Emphasizing that the "special protections and provisions of the Juvenile Court Act" were an entitlement that could not be taken away without due process, Justice Abe Fortas declared that "there is no place in our system of law for reaching a result of such tremendous consequences without ceremony - without hearing, without effective assistance of counsel, without a statement of reasons." Justice Fortas outlined specific criteria, including the seriousness of the alleged offense, history and the "likelihood of reasonable rehabilitation" that juvenile court judges were supposed to use to make this "critically important" decision. Surprisingly, the Roberts court, despite Justice Roberts's own misgivings, has been at the forefront of resuscitating the juvenile court ideal of individualized justice for children. This all started in 2005, in the final days of the Rehnquist court, with Justice Anthony M. Kennedy's landmark decision in Roper v. Simmons, which abolished the juvenile death penalty. Justice Kennedy drew on scientific research to explain why adolescents were different from adults. This research demonstrated that teenagers were immature, more susceptible to peer pressure and still developing their personalities and character. Most juvenile justice experts, however, predicted that the Roberts court would limit the decision made in Roper. All the court had to do was to use a subsequent case to declare that homicide was different from other criminal sanctions. The court has energetically resisted interpreting the Eighth Amendment, which prohibits cruel and unusual punishment, as barring life terms for adults. Even so, in 2010, in the case Graham v. Florida, the Roberts court declared that life sentences for juveniles in nonhomicide cases, without the possibility of parole, violated the amendment. This week's decision demonstrates that there is no turning back. It also reminds us why we created the juvenile court in the first place and why no state has abolished its juvenile justice system. The juvenile court, as it turns out, is also the nation's most successful legal export. Every major industrialized democracy in the world has a juvenile justice system built on the enduring idea that children are different. In his dissenting opinion in the 2012 case, Chief Justice John G. Roberts Jr. cautioned that unless the idea that "children are different" is confined, "the only stopping point for the Court's analysis would be never permitting juvenile offenders to be tried as adults." But in light of the court's history, Chief Justice Roberts should worry about whether this principle can be contained any longer. After all, it was his court that gave it new life. David S. Tanenhaus, a professor of history and law at the University of Nevada, Las Vegas, is the author of "The Constitutional Rights of Children: In re Gault and Juvenile Justice."