After last week's oral arguments in a U.S. Supreme Court case concerning the sentencing of juvenile offenders, advocates on both sides say it's unclear how the court, which has changed in composition since the last major rulings on the issue, will interpret those precedents.

Observers said the justices didn't give much away during their questioning Tuesday in Jones v. Mississippi, which concerns how states should interpret and implement a previous high court ruling that declared life without parole sentences for juvenile offenders to be unconstitutional unless a defendant was found to be "permanently incorrigible."

"It's so different listening [remotely] from watching because you can't even see their facial expressions or the body language," Marsha Levick of the Juvenile Law Center said. "I don't have any sense of how they'll rule."

The case challenges the sentence of Brett Jones for killing his grandfather in 2004. After the Supreme Court's 2012 decision in Miller v. Alabama , in which the justices found that life without parole sentences should only be allowed for those found to be incapable of rehabilitation, Jones was resentenced, but the court once again decided to give him life without parole.

At oral arguments, Jones argued that the state of Mississippi, including the Mississippi Supreme Court when it heard his appeal, did not properly recognize and follow Miller. The state has refused to say that in order to sentence a juvenile offender to life without parole, the defendant must also be found to be permanently incorrigible. Making this finding, Jones attorney David Shapiro argued, is a prerequisite for imposing such a sentence.

Mississippi, meanwhile, argued via its attorney Krissy C. Nobile that the state had met its requirements under Miller since the sentencing judge considered Jones' youth alongside other factors.

Currently, several state supreme courts have split on whether or not a state court has to make that specific finding of "permanently incorrigible" to sentence a juvenile to life without parole, or whether a consideration of youth is enough.

On Tuesday, both attorneys faced pointed questions from the justices, including many questions for Shapiro from the conservative justices as to whether what he was asking for would further expand the mandate in Miller. Nobile, meanwhile, was repeatedly asked whether her position was compatible with the court's decision in Montgomery v. Alabama , which made Miller retroactive and made clear that Miller was a substantive ruling.

Observers said it was difficult to guess how the justices might come down.

"It's truly hard to tell," said Kymberlee Stapleton, an attorney at the Criminal Justice Legal Foundation, which submitted an amicus brief supporting the state.

Both Stapleton and Levick also said that the calculus was made more complicated by the changes in the court since 2012. Of the five justices who made up the majority in Miller, two, Justice Anthony Kennedy and the late Justice Ruth Bader Ginsburg, are no longer on the court.

And with the additions to the court of Justices Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett over the last four years, it is possible that the justices who did not support the conclusions in Miller will vote against further enshrining them and will have additional support for that decision.

"There are certain judges who [dissented] in Miller and Montgomery who I think are going to stick to what they said in those cases — namely Thomas and Alito," Stapleton said. "As for the other ones, it's hard."

For instance, although Justice Elena Kagan wrote the majority opinion for Miller, Stapleton said the justice seemed to be questioning during oral arguments how to read Miller and Montgomery together.

Levick, however, said she thinks there is a good chance Justice John Roberts at least will side with Jones, noting that he also voted to make Miller retroactive in the Montgomery decision.

"Roberts, it seemed to me, in Montgomery ... didn't agree with the underlying ruling, but once Miller came down, he agreed that it had the sufficient characteristics that it needed to be held retroactive," she said.

The three newest members of the court, however, remain something of a mystery, especially Justice Barrett, who was sworn in as on Oct. 27. During oral arguments, Justice Barrett questioned both attorneys about Jones' right to appeal under the Eighth Amendment, at one point asking Shapiro why his client couldn't simply argue that his sentencing judge had erred and that Jones was capable of rehabilitation.

"We did, your honor," Shapiro replied. "But the problem is that the Mississippi courts don't recognize that permanent incorrigibility is a rule."

Levick said she wasn't sure where Justice Barrett was going with her questions, or what — if anything — they might indicate.

Both Levick and Stapleton said that there are few clues in Justice Barrett's short history as a judge as to what her thinking might be on the issues involved in the case.

Mary McCord, an attorney who represented current and former prosecutors, DOJ officials, and judges in an amicus brief opposing the sentence, said that because Jones' resentencing was conducted before Montgomery was decided, the Supreme Court could rule narrowly in this case, remanding for a resentencing that reflects that decision.

"Because of the posture of this case ... it could be very limited," she said, adding that she prefers not to try to predict how the justices will come down.

Levick and Stapleton also said a ruling for Mississippi would be unlikely to erode the Miller decision itself. Levick noted that the ruling has been implemented in different ways in different states, and that if the high court found for Mississippi, that state of affairs would likely continue.

"I don't think Miller is on the chopping block here," she said. "There are a number of jurisdictions around the country that are [implementing Miller in line with Jones' argument]. ... And I think it's also true that good defense lawyers are really pushing for those determinations, and they are appealing when they don't get them, and the appellate courts are examining them."

A favorable ruling, however, would cement Montgomery and make those protections stronger and more universal across all 50 states, Levick said.

Stapleton said she worried that a ruling for Jones would grant the opportunity for parole to juvenile offenders who had been denied it for years or even decades, meaning victims' families would have to deal with parole hearings.

"Some of these cases could be 40 years old, 50 years old," she said. "It would be a huge impact on victims' families to have to go through all this again, years and years later."

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--Editing by Breda Lund.

Correction: A previous version of this story misspelled Justice Ginsburg's name. This error has been corrected.