Washington state's Supreme Court on Thursday ruled that sentencing juveniles to life in prison without the chance for parole is unconstitutional.

The court ruled 5-4 to uphold a state court of appeals ruling that a statute that allows 16- and 17-year-olds to be sentenced to life without parole violated the state's ban on cruel punishment.

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"We hold that sentencing juvenile offenders to life without parole or early release constitutes cruel punishment and, therefore, is unconstitutional," Justice Susan Owens wrote in the Supreme Court's majority opinion.

The state had challenged the court of appeals' ruling, arguing that it "subverted the constitutional authority of a duly-elected legislature to fix punishments for criminal offenses" by ruling the sentence unconstitutional.

The United States Supreme Court ruled in 2012 that life sentences for anyone under the age of 18 were unconstitutional.

The legal battle in Washington state stems from a case involving Brian Bassett, who was 16 when he was kicked out of his home by his parents. He later returned to the home and shot his parents.

He was convicted of three counts of aggravated first-degree murder for the deaths of his mother, father and brother, and he was sentenced to life without parole.

Thursday's ruling will send Bassett, as well as other individuals who have been sentenced to juvenile life without parole, back to trial for re-sentencing.