625 ILCS 5/18c-3303

Failure to Reject or Suspend, or to Invoke Sanctions, Not to be Construed as Acceptance. Failure of the Commission to reject or suspend any rate, contract, application, or other document filed with it, or to initiate enforcement proceedings or invoke sanctions against any person for action or violation of this Chapter, Commission regulations or orders, shall not be construed in any proceeding of either any administrative or judicial nature as authorization or acceptance of such document or action, or any portion thereof. Nothing in this Section shall be construed to affect the date on which a rate or tariff is lawfully in effect.