18.12—Amicus curiae.
A brief of an amicus curiae may be filed only with the written consent of all parties, or by leave of the administrative law judge granted upon motion, or on the request of the administrative law judge, except that consent or leave shall not be required when the brief is presented by an officer of an agency of the United States, or by a state, territory or commonwealth. The amicus curiae shall not participate in any way in the conduct of the hearing, including the presentation of evidence and the examination of witnesses.