305 ILCS 5/10-13.2: Hearings not subject to technical rules of evidence or procedure.

In the conduct of any hearing or investigation, neither the Illinois Department nor a person duly authorized to conduct such hearing or investigation, shall be bound by the technical rules of evidence, common law or statutory, or by technical or formal rules of procedure, but shall conduct the hearing or make the investigation in such manner as seems best calculated to conform to substantial justice and the spirit of this Code. No informality in any proceedings, or in the manner of taking testimony, shall invalidate any order or decision made by the Illinois Department pursuant to such hearing or investigation.