Ill. Admin. Code tit. 62, § 1848.8 – Intervention

a) Any person may petition for leave to intervene at any stage of a proceeding under 62 Ill. Adm. Code 1847.
b) A petitioner for leave to intervene shall incorporate in the petition a statement setting forth the interest of the petitioner and, if he had a statutory right to initiate the proceeding, a showing of why his interest is or may be adversely affected.
c) The Department or the hearing officer shall grant the petition to intervene where the petitioner:
1. 1) Had a statutory right to initiate the proceeding in which he wishes to intervene; or
2. 2) Has an interest which is or may be adversely affected by the outcome of the proceeding.
d) If neither subsection (c)(1) nor (c)(2) above apply, the hearing officer or the Department shall consider the following in determining whether intervention is appropriate:
1. 1) The nature of the issues;
2. 2) The adequacy of representation of petitioner's interest which is provided by the existing parties to the proceeding;
3. 3) The ability of the petitioner to present relevant evidence and argument; and
4. 4) The effect of intervention on the agency's implementation of its statutory mandate.
e) Any person granted leave to intervene in a proceeding shall participate in such proceeding as a full party or, if permitted by the Department or the hearing officer, in a capacity less than that of a full party. If an intervener wishes to participate in a limited capacity, the extent and the terms of such participation shall be at the discretion of the Department or the hearing officer and shall be defined by the Department or the hearing officer.