Your son is entitled to defend against this accusation in an internal administrative appeal. The school will, on your request, advise you of the details and requirement for accessing the admin appeal process, including the critical (and short) time deadlines. It is important to exercise the right to admin appeal as the accusation he is facing can have severe consequences for his future. You may want to engage legal counsel to signal to the school that this matter is not going to be received lightly.
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