215 ILCS 5/12

(1) The incorporators shall adopt by-laws for the company and such by-laws may not be altered, amended, or repealed, prior to the issuance of a certificate of authority to the company, except by written consent of subscribers representing at least two-thirds of the shares subscribed, and the approval of the Director. (2) After a certificate of authority is issued to a company, the power to make, alter, amend or repeal by-laws shall be vested in the board of directors unless reserved to the shareholders by the articles of incorporation.