You have to understand, the sucker punch is the coward's tool, or the bully's tool. It's essentially getting a real quick an powerful blow in, while the other guy (read: victim) has no idea there is going to be a fight. You can sucker punch anyone, there's no real trick to it. It just takes a low-life scumbag to do it.
If I were on the jury I'd vote to acquit.
Well perhaps; I've had virtually no experience fighting (except with siblings), so I'm not going to argue. I'll say the guy deserved a punch (of some sort), or, better yet if possible, a public humiliation over how bad a parent and member of society he is.