Your son should not be harassed by a teacher for any reason, but especially if he was found not guilty. It is hard to sue schools but whether or not you can depends on how the school conducted the investigation. Report the harassment to the principal of the school and copy the superintendent.
An attorney reviewing this case will have many questions about the situation, what happened in the investigation, and if the school is to blame more than the girl. Only then could you decide if you have a legal action against the school and if you want to pursue it.
Answered on Apr 13th, 2013 at 7:40 PM