I had my kids in karate at age 4.

Maybe mine aren't as unteachable as most, but they definitely could learn what is allowed and when in self-defense. It might on the karate school.

They sparred with tons of kids in class, and they each had to use their karate to some extent in defense of themselves or others.

The only times they would get angry and dangerous when sparring is when they were sparring each other. Anything that they would see as an accident if done by a non-relative was always seen as intentional if done by a sibling.

Only one of them ever threw the first punch. He was getting mocked by a group of kids from about 6th grade to about 11th grade. Always telling them to stop. One day in lunch at the high school he decided he had enough. He told the kid he was done putting up with it, and if he said one more thing, he was going to punch him in the face.

The kid said it, got punched, and then no one ever said anything again.

There was a school security guard that saw the whole thing. Either he decided the other kid deserved it, or he decided he didn't want to have to deal with my son. Probably the former, but the latter isn't outside the realm of possibility.