Section R. 408.21423 - InterventionRule 423.
(1) A petition for leave to intervene may be filed at any stage of a proceeding before commencement of the hearing.(2) The petition shall set forth the interest of the petitioner in the proceeding and show that the participation of the petitioner shall assist in the determination of the issues in question, and that the intervention shall not unnecessarily delay the proceeding.(3) The board or the hearings officer may grant a petition for intervention to such an extent and upon such terms as the board or the hearings officer determines.Mich. Admin. Code R. 408.21423