27 C.F.R. § 71.31
A respondent or applicant may be represented by an attorney, certified public accountant, or other person enrolled to practice before the Alcohol and Tobacco Tax and Trade Bureau under 31 CFR part 8 -Practice before the Alcohol and Tobacco Tax and Trade Bureau. The representative shall file in the proceeding a duly executed power of attorney to represent the applicant or respondent. See 26 CFR 601.501 through 601.527 (conference and practice requirements). The appropriate TTB officer shall be represented in proceedings under this part by the attorney for the Government who is authorized to execute and file motions, briefs, and other papers in the proceeding, on behalf of the appropriate TTB officer, in his own name as "Attorney for the Government".
27 C.F.R. §71.31