(a) An interested person may make an appearance, including a personal appearance at the discretion of the OHA, and participate in any proceeding described in this part on his own behalf or by a duly authorized representative. Any document filed by a duly authorized representative must contain a statement by such person certifying that he is a duly authorized representative.

(b) The OHA may deny, temporarily or permanently, in whole or in part, the privilege of participating in proceedings, including oral presentation, to any individual who is found by the OHA—

(1) To have made false or misleading statements, either orally or in writing;

(2) To have filed false or materially altered documents, affidavits or other writings;

(3) To lack the specific authority to represent the party or participant; or

(4) To have engaged in or to be engaged in conduct that substantially disrupts a proceeding.