28 C.F.R. § 18.10 – Rehearing.

(a) Any appellant dissatisfied with a final agency decision under § 18.9 may, within 30 days after the notice of the final agency decision is sent, request the responsible agency official to re-review the record, and present additional evidence which is appropriate and pertinent to support a different decision.
(b) If the responsible agency official finds that the appellant has:
1. (1) Presented evidence or argument which is sufficiently significant to require the conduct of further proceedings; or
2. (2) Shown some defect in the conduct of the initial hearing sufficient to cause substantial unfairness or an erroneous finding in that hearing, the responsible agency official may require that another oral hearing be held on one or more of the issues in controversy, or permit the dissatisfied party to present further evidence or argument in writing.
(c) Any rehearing ordered by the responsible agency official shall be conducted pursuant to §§ 18.5-18.8.