65 ILCS 5/4-9-3
Every public utility shall provide equal and uniform service to all residents of any municipality adopting, or which is treated as having adopted, this article. It shall be unlawful and a sufficient ground for the forfeiture of any franchise for a public utility to grant free service, or to furnish better service, or to furnish service at a lower price or rate, quantity and quality considered, to any person, or otherwise to discriminate in the matter of rates or service between residents of any such municipality. Whenever the council receives proof that this section is being violated, they shall summon witnesses and investigate at once, and if they so find, they shall immediately institute a suit to have the franchise forfeited. However, the council shall have power by ordinance to grant a public utility the right to grant reduced rates to persons specified in the ordinance. Also, the council, by ordinance, may authorize any street railway, interurban railway, bus company or other public transportation system to transport free any member, while in uniform, of the police or fire department of the city within the corporate limits thereof, and may authorize the giving of such free transportation in other cases where there is no conflict with Section 4-8-6, or with the general law of the State, or with any act of Congress.
Any person or public utility violating this section, and any person accepting any preference specified in this section, shall be guilty of a Class A misdemeanor. Any person receiving any special favor or privilege specified in this section, shall be immune from punishment in case he testifies to any matter referred to in this section in pursuance of subpoena from the council.
65 ILCS 5/4-9-3