5 U.S. Code § 501
5 U.S. Code § 501 is about Advertising practice; restrictions. It is under Part 1 (Administrative Procedure) Subchapter 1 (General Provisions) Chapter 5 (Administrative Procedure) of Title 5 (Government Organizations and Employees) of the Code.
An individual, firm, or corporation practicing before an agency of the United States may not use the name of a Member of either House of Congress or of an individual in the service of the United States in advertising the business.