For the two dozen or so states that automatically hand out life without parole or LWOP sentences to juveniles convicted of murder, the U.S. Supreme Court says that's unconstitutional.
In fact, the majority of justices declared: LWOP is cruel and unusual punishment under the Eighth Amendment given kids' brains and self-control are not fully developed enough to make good choices.
"What it does is it sends a signal, in my view a signal that we remain a humane society that says in the final analysis children are different than adults and need to be treated differently," University of the Pacific McGeorge School of Law professor John Myers said.
In California, life-without-parole sentences are not automatic for kids who kill, but judges do have discretion in handing that out; the ruling preserves that option.
More than 300 inmates are in our state prison for murders they committed under the age of 18. The number is 2500 nationwide.
Crime victims are outraged and say juveniles who commit adult crimes should be treated like adults.
"You're trying to tell me their brain is not developed enough to know that you don't murder? What kind of message are we sending out? Particularly to the gangs?" Crime Victims United spokesperson Harriet Salarno said.
It's unclear what the ruling means for California murderers convicted as minors, but some legal experts think lawyers could use it to get sentences changed to life with parole.
Child psychologist and State Senator Leland Yee is still pursuing legislation allowing certain LWOP killers convicted as minors to at least get a periodic review for release.
"While they may have committed adult crimes, the fact is they're still kids," Yee said.
California-native Justice Anthony Kennedy, a Republican-appointee, provided the swing vote 5-4 as he does in many high-profile cases.