To the supreme court for this decision.
Honestly, I see nothing wrong with minors (read: individuals under the age of 18) being able to purchase or own violent video games. Hell, most kids my the time they're 13 have probably played/seen something that involved extreme violence, whether it be TV, movies, games, etc. The same principle could be said for sexual topics in video game media, but that's another matter entirely.
Not to mention, there's no harm in allowing kids/teens to play violent games; I for one played Resident Evil 4 (an M rated shooter) when I was only 15, and it had no ill effects on me what so ever (except I'm now a serial killer ). I've also been watching R rated movies and South Park since I was a kid, like so many other of my peers. Thus lessoning restrictions on violent games is a good thing, cause minors are already use to such forms of media.