Legal Assistant. A person, working under the supervision of a lawyer, qualified through education, training, or work experience to perform substantive legal work that requires knowledge of legal concepts and is customarily, but not exclusively, performed by a lawyer; also known as a paralegal.egal assistants cannot represent a client or give legal advice. All work performed by legal assistants must be done under the supervision of an attorney, who is subject to disciplinary procedures for ethical violations committed by the legal assistant.