18 U.S.C. 203 prohibits Federal employees from receiving, agreeing to receive, or soliciting compensation for representational services, rendered either personally or by another, before any court or Federal agency or other specified Federal entity, in connection with any particular matter in which the United States is a party or has a direct and substantial interest. (Link to 18 U.S.C. 203 for more information)
18 U.S.C. 205 prohibits Federal employees from personally representing anyone before any court or Federal agency or other specified Federal entity, in connection with any particular matter in which the United States is a party or has a direct and substantial interest. Unlike section 203, this prohibition applies whether or not the employee receives any compensation for her or his representational activity. Furthermore, this section also prohibits an employee from representing anyone in the prosecution of a claim against the United States, or from receiving any gratuity, or share or interest in a claim, as a consideration for assistance in prosecuting the claim. (Link to 18 U.S.C. 205 for more information)
Violation of either of these statutes can result in criminal prosecution.