18 U.S.C. § 292

Whoever solicits employment for himself or another in respect to a case, claim, or award for compensation under, or to be brought under, subchapter I of chapter 81 of title 5; or Whoever receives a fee, other consideration, or gratuity on account of legal or other services furnished in respect to a case, claim, or award for compensation under subchapter I of chapter 81 of title 5, unless the fee, consideration, or gratuity is approved by the Secretary of Labor— Shall, for each offense, be fined under this title or imprisoned not more than one year, or both.