50 ILCS 725/3.8

(a) No officer shall be interrogated without first being advised in writing that admissions made in the course of the interrogation may be used as evidence of misconduct or as the basis for charges seeking suspension, removal, or discharge; and without first being advised in writing that he or she has the right to counsel of his or her choosing who may be present to advise him or her at any stage of any interrogation. (b) It shall not be a requirement for a person filing a complaint against a sworn peace officer to have the complaint supported by a sworn affidavit or any other legal documentation. This ban on an affidavit requirement shall apply to any collective bargaining agreements entered after the effective date of this provision.