Abba/S………..
The original post suggests that the Principal put hands on the child and tossed him out the door. Why then talk to the principal?
I apologize I thought it was only Rabbi.I find it hard to believe that a Principal would come into a classroom and just grab a student by the neck and throw him out the door. Most yeshivas have a Financial Director and a Chairmen of the Board who you can complain to instead of the principal. Why not give the Rabbi the benefit of the doubt and have the child checked out by a medical professional. Who if abuse is seen, must, by law, report it to the authorities rather then falsely accuse him of abuse.
As far as a criminal complaint, unless the student wants to press charges and you actual witnessed it, the police will do nothing.
As far as suing the rabbi or yeshiva ,you wouldn’t collect a dime from them. Maybe you will collect something from the insurance company, if they have insurance. So unless you have a pro bono lawyer this isn’t going anywhere.