The Indiana Supreme Court has determined a judge wrongly considered the condition of the state's mental health system in rejecting an insanity defense for a man convicted of stabbing his grandmother to death in front of family members.

In a 3-2 decision Wednesday, the justices said it was inappropriate for the judge to consider whether Gregory Galloway may have eventually been released if he was sent to a mental health facility.

Instead, he was found guilty but mentally ill and was sentenced to 50 years in prison. If he had been found insane, Galloway would have been sent to a mental hospital instead of prison.

"It is not for the judicial branch to decide that a legally insane defendant should be convicted and sentenced to prison because of the condition of the state's mental health system," Justice Frank Sullivan wrote in the 23-page ruling. "While we sympathize with the difficulty of the trial court's decision, we cannot sustain it."