Ill. Admin. Code tit. 11, § 1900.825
b) If the petitioner believes the ALJ is biased or has a conflict of interest, the petitioner may file with the Board a motion to disqualify the ALJ from conducting the hearing. The motion must be in writing, accompanied by an affidavit signed and dated by the petitioner setting forth the specific grounds for disqualification. The petitioner shall serve a copy of the motion on the ALJ. Prior adverse rulings against the petitioner or its attorney in other matters shall not, in and of themselves, constitute grounds for disqualification. On satisfactory evidence submitted by the petitioner in support of the motion to disqualify, the Board shall remove the ALJ and provide for the reassignment of the case to another ALJ to continue the hearing. Any ALJ may voluntarily disqualify himself or herself upon determining that bias or conflict of interest exists. Grounds for disqualification of an ALJ shall include but not be limited to: