Section 625 ILCS 5/18c-3207 - Zones of Rate Flexibility(1) Zone for Motor Carriers of Passengers. Notwithstanding any other provisions of this Sub-chapter, the Commission may not investigate, suspend, revise, or revoke any single-line rate proposed by a motor carrier of passengers, or joint rate proposed by one or more such companies, applicable to any transportation on the grounds that such rate is unreasonably high or low if: (a) The rate was published in accordance with provisions of this Chapter, Commission regulations and orders;(b) The Commission was properly notified that the carrier or carriers wish to have the rate considered pursuant to this subsection; and(c) The net of all increases and decreases, during the calendar year in which the rate is to become effective, is not more than 25%.(2) Zone for Rail Carriers. Notwithstanding any other provision of this Sub-chapter the Commission may not investigate, suspend, revise, or revoke any rate proposed by a rail carrier on the grounds that such rate is unreasonably high or low if: (a) The rate was published in accordance with provisions of this Chapter and Commission regulations;(b) Commission was properly notified that the carrier wished to have the rate to be considered pursuant to this subsection; and(c) The net of all increases and decreases, during the calendar year in which the rate is to become effective, is not more than the amount specified under 49 U.S. Code 10707a and 10708.(3) Commission to Adopt Regulations. The Commission may adopt regulations specifying procedures for determining whether a rate published by a carrier falls within the zone of rate flexibility.