220 ILCS 5/5-101
Every public utility shall furnish to the Commission all information required by it to carry into effect the provisions of this Act, and shall make specific answers to all questions submitted by the Commission.
Any public utility receiving from the Commission any blanks with directions to fill the same, shall cause the same to be properly filled out so as to answer fully and correctly each question therein propounded, and in case it is unable to answer any question, it shall give a good and sufficient reason for such failure; and said answer shall be verified under oath by the president, secretary, superintendent or general manager of such public utility and returned to the Commission at its office within the period fixed by the Commission.
Whenever required by the Commission, every public utility shall deliver to the Commission, any or all maps, profiles, reports, documents, books, accounts, papers and records in its possession, or in any way relating to its property or affecting its business, and inventories of its property, in such form as the Commission may direct, or verified copies of any or all of the same.
Every public utility shall obey and comply with each and every requirement of this Act and every order, decision, direction, rule or regulation made or prescribed by the Commission in the matters herein specified, or any other matter in any way relating to or affecting its business as a public utility, and shall do everything necessary or proper in order to secure compliance with and observance of this Act and every such order, decision, direction, rule or regulation by all of its officers, agents and employees.
220 ILCS 5/5-101