27 CFR 771.31: Attorneys and other representatives.

An applicant, licensee, or permittee may represent himself, or be represented by an attorney, a certified public accountant, or any other person, specifically designated in a duly executed power of attorney that shall be filed in the proceeding by the applicant, licensee, or permittee. The applicant, licensee, or permittee shall file waivers, if applicable, under the Privacy Act of 1974 and 26 U.S.C. 6103(c) (confidentiality and disclosure of returns and return information). The Director of Industry Operations may be represented in proceedings by an attorney in the Office of Chief Counsel who is authorized to execute and file motions, briefs, and other papers in the proceeding on behalf of the Director of Industry Operations, in the attorney's own name as “Attorney for the Government.”