(a) The affected applicant or recipient to whom a notice of hearing or a notice of an opportunity for hearing has been mailed in accordance with part 17 of this title and § 4.815, and the Director, are the initial parties to the proceeding.

(b) Other persons or organizations shall have the right to participate as parties if the final decision could directly and adversely affect them or the class they represent, and if they may contribute materially to the disposition of the proceedings.

(c) A person or organization wishing to participate as a party under this section shall submit a petition to the administrative law judge within 15 days after the notice has been served. The petition should be filed with the administrative law judge and served on the affected applicant or recipient, on the Director, and on any other person or organization who has been made a party at the time of filing. Such petition shall concisely state: (1) Petitioner's interest in the proceeding, (2) how his participation as a party will contribute materially to the disposition of the proceeding, (3) who will appear for petitioner, (4) the issues on which petitioner wishes to participate, and (5) whether petitioner intends to present witnesses.

(d) The administrative law judge shall promptly ascertain whether there are objections to the petition. He shall then determine whether petitioners have the requisite interest to be a party in the proceedings, as defined in paragraphs (a) and (b) of this section, and shall permit or deny participation accordingly. Where petitions to participate as parties are made by individuals or groups with common interests, the administrative law judge may request all such petitioners to designate a single representative, or he may recognize one or more of such petitioners to represent all such petitioners. The administrative law judge shall give each such petitioner written notice of the decision on his petition. If the petition is denied, he shall briefly state the grounds for denial and shall then treat the petition as a request for participation as amicus curiae. The administrative law judge shall give written notice to each party of each petition granted.

(e) Persons or organizations whose petition for party participation is denied may appeal the decision to the Director, Office of Hearings and Appeals, within 7 days of receipt of denial. The Director, Office of Hearings and Appeals, will make the final decision for the Department to grant or deny the petition.