710 ILCS 35/4

(a) Except as otherwise provided in Section 6, a mediation communication is privileged as provided in subsection (b) and is not subject to discovery or admissible in evidence in a proceeding unless waived or precluded as provided by Section 5. (b) In a proceeding, the following privileges apply: (1) A mediation party may refuse to disclose, and may prevent any other person from disclosing, a mediation communication. (2) A mediator may refuse to disclose a mediation communication, and may prevent any other person from disclosing a mediation communication of the mediator. (3) A nonparty participant may refuse to disclose, and may prevent any other person from disclosing, a mediation communication of the nonparty participant. (c) Evidence or information that is otherwise admissible or subject to discovery does not become inadmissible or protected from discovery solely by reason of its disclosure or use in a mediation.