49 CFR 511.75: Persons not attorneys.

(a) Any person who is not an attorney at law may be admitted to appear in an adjudicative proceeding if that person files proof to the satisfaction of the Presiding Officer that he or she possesses the necessary legal, technical or other qualifications to render valuable service in the proceeding and is otherwise competent to advise and assist in the presentation of matters in the proceedings. An application by a person not an attorney at law to appear in a proceeding shall be submitted in writing to the Docket Section, not later than thirty (30) days prior to the hearing in the proceedings. The application shall set forth the applicant's qualifications to appear in the proceedings.

(b) No person who is not an attorney at law and whose application has not been approved shall be permitted to appear in the Administration's proceedings. However, this provision shall not apply to any person who appears before the NHTSA on his or her own behalf or on behalf of any corporation, partnership, or association of which the person is a partner, officer, or regular employee.