The Supreme Court has refused to review a 30-year prison sentence for a teen who was 12 when he killed his grandparents in South Carolina.

Lawyers for Christopher Pittman wanted the justices to examine whether the long prison term for a child violates the Constitution's ban on cruel and unusual punishment. With no possibility of parole, he will be 42 before he is released, they said.

Pittman is the only inmate serving such a lengthy sentence for a crime committed at such a young age, his lawyers said. The judge who sentenced him was prohibited by law from taking his age into account.

South Carolina contended the punishment is proportionate to the crime and said there is a national trend of increased punishment for young violent criminals.