Awhile back california tried to ban* the sale of 'violent' games to minor (under 18). The supreme court just ruled that this law is unconstitutional as it violates the first amendment right to free speech. The decision was 7-2
http://www.cnn.com/2011/US/06/27/scotus.video.games/
Specifically they said the law was too broad and that there was a tradition of exposing children to violence (like in fairy tales) and that this law infringed on a parents right to make that choice. Unfortunately that means that a more narrow and speciic law could be written that would not be covered by this precedent.
Of course most retailor still enforce the ESRB ratings on the grounds that they can refuse service to anyone on any non-discriminatory grounds, which means no M rated games for minors at major retailors.
Anyway, just thought you guys would want to know.
*california likes to try and ban everything