WASHINGTON — The Supreme Court has made it easier to sentence minors to life in prison without the possibility of parole if they are convicted of murder.

The current case involved a Mississippi inmate and a crime committed when he was 15. Brett Jones stabbed his grandfather to death during an argument about Jones' girlfriend in 2004. He was convicted of murder in the 68-year-old's death and sentenced to life without parole.

Justices were considering whether a minor has to be found to be incapable of being rehabilitated before being sentenced to life without parole.

In a 6-3 decision Thursday that split the justices along ideological lines, the court said no.

"In such a case, a discretionary sentencing system is both constitutionally necessary and constitutionally sufficient," the court's conservative justices wrote.

The ruling reflects a change in course driven by a more conservative group of justices. Over the years through a series of rulings, justices have struck down the death penalty for juvenile offenders and limited life-without-parole sentences to those juveniles convicted of murder who are so incorrigible there is no hope for rehabilitation.

In a dissent, Justice Sonia Sotomayor accused her colleagues of gutting earlier decisions that said life without parole sentences for people under age 18 should be rare.