Lawsuits over bullying? Whatever happened to defending yourself with your fists?
Two points: First, the criminal bullies are just another reason to home school.
Second, what?, you're going to sue some third-grader's parents if he takes your third-grader's lunch money? Teach your kid to fight. If he gets kicked out of school, so what.
If it's a matter of an older bully, say, a 12-year-old picking on a 7-year-old, the answer is similar, only it doesn't involve the kids, because your kid can't win. You should, by the way, teach him to fight back as best he can.
You visit the 12-year-old's father and tell him that if the bullying doesn't stop tomorrow, you'll be there tomorrow night and he'll get the same treatment. If 12-year-old doesn't have a father, well, you'll have to play it by ear.
Point is, you don't resolve with lawsuits what you can reasonably resolve with your fists.