I think martial arts is a great way for instill discipline in a child, also to see what hard work really is. It also instills confidence, and as has been seen on other forums when having to stand up to someone, which is very useful in difusing situations.

I took aikido, and the one thing I liked about it was it was a more defensive martial art. I think there was only 1 or 2 "offensive" moves, the rest of the moves required the "cooperation" of your attacker. Soemthing to think about. I have no idea about legal stuff, but I would think physics should stand up in court: "The only way I could have made that move, was for the person to attack me first".