820 ILCS 175/90

(a) Prohibition. It is a violation of this Act for a day and temporary labor service agency or third party client, or any agent of a day and temporary labor service agency or third party client, to retaliate through discharge or in any other manner against any day or temporary laborer for exercising any rights granted under this Act. Such retaliation shall subject a day and temporary labor service agency or third party client, or both, to civil penalties pursuant to this Act or a private cause of action. (b) Protected Acts from Retaliation. It is a violation of this Act for a day and temporary labor service agency or third party client to retaliate against a day or temporary laborer for: (1) making a complaint to a day and temporary labor service agency, to a third party client, 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.