235 ILCS 5/8-6
The Department, or any officer or employee designated in writing by the Director thereof, for the purpose of administering and enforcing the provisions of this Act, may hold investigations and hearings concerning any matters covered by this Act. In holding or conducting any hearing or investigation authorized under this Act, the Department or any officer or employee of the Department designated, in writing, by the Director thereof, may examine any books, papers, records or memoranda bearing upon the manufacture, importation, sale or use of alcoholic liquors by any licensee, and may require the attendance of such licensee or of any officer, agent or employee of such licensee, or of any person having knowledge of such facts, and may take testimony and require proof for its information. In the conduct of any investigation or hearing, neither the Department nor any officer or employee thereof shall be bound by the technical rules of evidence, and no informality in any proceeding, or in the manner of taking testimony, shall invalidate any assessment, order, decision, rule or regulation made or approved or confirmed by the Department. The Director of Revenue or any duly designated officer or employee of the Department shall have power to administer oaths to such persons; and the Department shall have the power to issue subpoenas and subpoenas duces tecum, and the Department, or any other party to a proceeding pending before the Department, may apply to the circuit court to compel the attendance and testimony of witnesses and the production of books, papers, records and memoranda, by an attachment for contempt as provided for such purposes in civil cases.
The Department or any officer or employee thereof, or any party in an investigation or hearing before the Department, may cause the depositions of witnesses within the State to be taken in the manner prescribed by law for like depositions in civil actions in courts of this State, and to that end compel the attendance of witnesses and the production of books, papers, records and memoranda.
The books, papers, records and memoranda of the Department, or parts thereof, may be proved in any hearing, investigation or judicial proceeding by a reproduced copy thereof under the certificate of the Director of Revenue. Such reproduced copy shall, without further proof, be admitted into evidence before the Department or in any judicial proceeding.
235 ILCS 5/8-6