Michigan Governor Rick Snyder has signed a law changing sentencing rules for juvenile defendants convicted of murder and other serious crimes.
Legislation signed Tuesday brings Michigan into compliance with a 2012 U.S. Supreme Court ruling that struck down mandatory life imprisonment for juveniles.
Prosecutors can still seek life sentences without parole, but they can't be mandatory on judges.
If juveniles don't get life without parole, judges now have to sentence them to a minimum of at least 25 years and a maximum of at least 60 years.
The law doesn't apply retroactively to more than 300 Michigan inmates under 18 when they committed their crimes.
The Michigan Supreme Court will hear arguments Thursday on whether those prisoners should get new sentences that could someday lead to their parole.