(LANSING) -- The Michigan appeals court has heard arguments in a case that could determine whether prisoners locked up for murder when they were teens will be given a shot at parole. The issue is whether a recent U.S. Supreme Court decision should apply retroactively to more than 350 people serving mandatory life sentences with no chance of parole. The Supreme Court says that such punishments for minors are unconstitutional. Attorney General Bill Schuette says the ruling shouldn't benefit people already in prison. The state appeals court heard arguments Tuesday in the case of a St. Clair County man, Raymond Carp, who was convicted of murder committed when he was 15. The judges are William Whitbeck, Michael Talbot and E. Thomas Fitzgerald.