Well, bullies sometimes don’t stop at bullying other children. I have known many kids who were “troubled” and if a teacher was tough on them (challenging them or giving them a zero b/c they didn’t do their work) the student would call (and tell the higher ups inthe school as well as their peers) the teacher a racist, sexist, pervert, or would say that the teacher touched them inappropriately (if the teacher touched them on the shoulder so that they would sit down and discontinue being disruptive) or said something inappropriate to the student (by calling the student “honey” or “dear” or “sweetheart” as many do of a certain generation). So, a kid that is nasty b/c s/he’s having a bad day is one thing, a kid who seems to have a lot of bad days and physically and/or emotionally beats up on and/or manipulates another student or a teacher to get his/her way (or so that the bad shadow is no longer cast on them) needs special attention that most private schools and many public schools are not equiped to handel. If the parents aren’t getting their children help, then the school has every right to expel the student. I believe private schools tolerate a lot more than public schools (at least in my experience).