The term 'prohibit legally' can be summarized by the crossword solution 'ESTOP'. ESTOP is a legal term which means to prevent or stop someone from doing something, usually through a court order. It is a form of legal prohibition which is used to prevent a person from taking certain actions or to prevent them from claiming certain rights. ESTOP is often used in cases where a person has been found to have acted unlawfully or in a manner that is contrary to public policy.