Supreme Court Justice Anthony M. Kennedy wrote two related opinions for the divided court, and it appeared from Tuesday’s arguments that he retained the pivotal role. (Damian Dovarganes/AP)

A majority of the Supreme Court on Tuesday seemed troubled by imposing mandatory life sentences on juveniles convicted of murder but struggled to balance proper punishment for young killers with the chance for redemption.

It was the court’s latest review of how juvenile criminals should be treated differently than adults. The justices previously have ruled out the death penalty for juveniles who kill and said life sentences without the possibility of parole are improper for juveniles whose crimes do not result in a death.

Justice Anthony M. Kennedy wrote both opinions for the divided court, and it appeared from Tuesday’s arguments that he retained the pivotal role.

The cases came from two 14-year-olds who were sentenced to life without parole for their roles in separate killings.

Evan Miller, a victim of abuse so severe that, his lawyer said, he had tried to kill himself five times, was convicted along with another juvenile of killing a neighbor, 52-year-old Cole Cannon, and setting afire Cannon’s trailer in Lawrence County, Ala.

The U.S. Supreme Court heard the cases of two 14-year-olds who were sentenced to life without parole for their roles in separate killings. (J. Scott Applewhite/AP)

Kuntrell Jackson of Blytheville, Ark., was with two other youths who attempted to rob a video store. One of the others used a sawed-off shotgun to kill 28-year-old clerk Laurie Troup.

Bryan Stevenson of the Equal Justice Initiative in Montgomery, Ala., represented both boys.

“We’re not suggesting that states should not be able to impose very harsh punishments and very severe sentences on even children who commit these kinds of violent crimes,” Stevenson told the court.

But he said the court recognized in the previous decisions that “deficits in maturity and judgment and decision making” make children less culpable for their crimes than adults.

“It is unusual, and it’s our judgment that it would be cruel, to declare these children fit only to die in prison,” he argued.

Alabama Solicitor General John C. Neiman Jr. told the court that 39 states allow life sentences for youths who kill. “Imposing life-without-parole sentences on aggravated-murder offenders like Evan Miller is in line with the national consensus, is morally justified and is consistent with legitimate penological goals,” he said.

There are 2,300 inmates serving life-without-parole sentences for murders committed before they were 18. But only 79 nationwide were 14 or younger at the time of their crimes, and about 90 percent of those are serving mandatory sentences.

The cases seem to give the justices a number of options if they do not agree with the states.

Justice Ruth Bader Ginsburg asked Stevenson whether it would be enough to ban mandatory life-without-parole sentences and let the judge consider mitigating circumstances.

Stevenson said it would not be enough, which prompted a rebuff from Kennedy.

“If you take that off the table, then you leave us with nothing but saying that the sentence is never permitted or that it’s always permitted,” Kennedy said.

Stevenson agreed that he was arguing for a categorical ban. But he said the court could also set some age limits. “We think that there is a basis for concluding, unquestionably, that a child under the age of 15 should not be exposed to life without parole based on this court’s precedents and on the data that’s presented,” he said.

He added that the court could also say that “subjecting any child under the age of 18 to life without parole where there is no ability to consider age is fundamentally at odds with what this court has now constitutionally recognized” in its previous cases.

“Do I just consult my own preferences on this matter?” asked Justice Antonin Scalia, who was Stevenson’s most persistent questioner. “Something like 39 states allow it. I mean, the American people, you know, have decided that that’s the rule. They allow it. And the federal government allows it.”

Justice Samuel A. Alito Jr. asked why it would make sense to say that someone just shy of his 18th birthday could not be given life in prison for “the worst possible string of offenses.”

Justice Steven G. Breyer went the opposite direction in questioning Neiman. “What’s the minimum age, in your opinion, or is there any constitutional minimum at all, in respect to which you could give for a murder a child life without parole?” he asked.

Justice Elena Kagan suggested that each juvenile’s case should be considered individually. Just as an adult cannot be given the death penalty without such an individualized sentencing, she said, perhaps no juvenile should be given life without parole without the same kind of consideration.

And the cases give the justices the potential for finding a difference between sentencing someone like Miller, who actively participated in the murder of his victim, and Jackson, who did not pull the trigger and whose role in the slaying is murkier.

“I do see a world of difference between the Miller killing and the Jackson killing, vis-a-vis the individual defendants’ personal liability,” Justice Sonia Sotomayor said.

The two cases are Miller v. Alabama and Jackson v. Hobbs .