45 C.F.R. § 160.506 – Rights of the parties.

(a) Except as otherwise limited by this subpart, each party may—
1. (1) Be accompanied, represented, and advised by an attorney;
2. (2) Participate in any conference held by the ALJ;
3. (3) Conduct discovery of documents as permitted by this subpart;
4. (4) Agree to stipulations of fact or law that will be made part of the record;
5. (5) Present evidence relevant to the issues at the hearing;
6. (6) Present and cross-examine witnesses;
7. (7) Present oral arguments at the hearing as permitted by the ALJ; and
8. (8) Submit written briefs and proposed findings of fact and conclusions of law after the hearing.
(b) A party may appear in person or by a representative. Natural persons who appear as an attorney or other representative must conform to the standards of conduct and ethics required of practitioners before the courts of the United States.
(c) Fees for any services performed on behalf of a party by an attorney are not subject to the provisions of 42 U.S.C. 406, which authorizes the Secretary to specify or limit their fees.