620 ILCS 5/51
The Department, or any officer thereof, and any employee thereof generally or specifically designated by it for such purpose shall have power to hold and conduct investigations, inquiries and hearings concerning any matters covered by the laws of this State pertaining to aeronautics, pursuant to such rules, rulings, regulations, orders, and decisions as the Department may establish or issue. In the conduct of any investigation, inquiry or hearing, neither the Department nor any officer nor employee thereof conducting the same shall be bound by the technical rules of evidence, and no informality in any proceeding or in the manner of taking testimony before the Department, or any officer or employee thereof, shall invalidate any order, decision, rule, ruling or regulation made, approved or confirmed by the Department. All hearings conducted by the Department shall be open to the public.
Each officer thereof and each employee thereof designated by it to hold any inquiry, investigation or hearing, shall have the power to administer oaths and affirmations, certify to all official acts, issue subpoenas, and compel the attendance and testimony of witnesses, and the production of papers, books, accounts and documents, either in person or by deposition in the manner provided in Section 53.
Hearings shall be held either by the Department or by an officer thereof or by any employee designated by it for such purpose. All evidence presented at hearings held by the Department or under its authority shall become a part of the records of the Department. In all cases in which the Department bases any action on reports of investigations or inquiries not conducted as hearings, such reports shall be made a part of the records of the Department.
620 ILCS 5/51