Section 220 ILCS 5/15-504 - Rate proceedings(a) Initiation of proceedings. The Commission may initiate a proceeding to investigate or prescribe tariffs or schedules on its own motion or complaint.(b) Suspension of tariffs. The Commission may suspend a tariff, in whole or in part, during the pendency of a proceeding to consider the reasonableness of the tariff, whether it is discriminatory, or whether it otherwise violates provisions of this Article, Commission regulations, or orders, provided the order of suspension is issued prior to the effective date of the tariff. The suspension shall remain in effect for 11 months unless the Commission order provides for a shorter period of suspension. At the end of the statutory suspension period, the suspension may be extended by agreement of the parties; otherwise, the tariff shall go into effect.(c) Burden of proof in investigation proceedings. The burden of proof in an investigation proceeding shall be on the proponent of the rate.(d) Prescription of tariffs and schedules. The Commission may prescribe tariffs if it has determined that a tariff published by a carrier is unreasonable, discriminatory, or otherwise in violation of this Article, Commission regulations, or orders. The Commission may prescribe schedules if it has determined, after a hearing, that a schedule filed by a carrier is in violation of this Article, Commission regulations, or orders.(e) Relief. The Commission may, if it finds a tariff or schedule is in violation of this Article, its regulations, or orders, or finds rates or provisions in a tariff unjust, unreasonable, or discriminatory, direct the carrier to: (1) Publish and file a supplement cancelling the tariff or file notice of cancellation of the schedule, in whole or in part;(2) Publish and file a new tariff or file a new schedule containing rates and provisions prescribed by the Commission; and(3) Repay any overcharges or collect any undercharges, and pay reparations.P.A. 89-42, eff. 1/1/1996.