(a) Agencies within the Department of Homeland Security. A broker who represents a client in the importation or exportation of merchandise may represent the client before the Department of Homeland Security or any representative of the Department of Homeland Security on any matter concerning that merchandise.

(b) Agencies not within the Department of Homeland Security. In order to represent a client before any agency not within the Department of Homeland Security, a broker must comply with any regulations of that agency governing the appearance of representatives before it.