820 ILCS 185/55: Retaliation.

(a) It is a violation of this Act for an employer or entity, or any agent of an employer or entity, to retaliate through discharge or in any other manner against any person for exercising any rights granted under this Act. Such retaliation shall subject an employer or entity to civil penalties pursuant to this Act or a private cause of action, or both.

(b) It is a violation of this Act for an employer or entity to retaliate against a person for:

(1) making a complaint to an employer or entity, to a co-worker, to a community organization, before a public hearing, or to a State or federal agency that rights guaranteed under this Act have been violated;

(2) causing to be instituted any proceeding under or related to this Act; or

(3) testifying or preparing to testify in an investigation or proceeding under this Act.