(PORT HURON) -- Michigan Attorney General Bill Schuette says a major U.S. Supreme Court decision shouldn't apply to inmates who already are serving no-parole sentences for murders committed when then they were teens. Schuette's staff this week filed a 29-page brief in the Michigan appeals court in the case of a St. Clair County man, Raymond Carp. He was 15 when he was involved in the brutal death of a woman in 2006. The Supreme Court has struck down mandatory no-parole sentences for juveniles. Schuette acknowledges that it applies to young people who are convicted in the future. But he says there should be no retroactive benefit for people already behind bars. More than 350 people are serving no-parole sentences in Michigan for crimes committed when they were under 18.