740 ILCS 165/2
A judgment in any jurisdiction for or against the plaintiff upon the substantive merits of any action for damages founded upon a single publication or exhibition or utterance as described in Section 1 shall bar any other action for damages by the same plaintiff against the same defendant founded upon the same publication or exhibition or utterance.
(from Ch. 126, par. 12)
(Source: Laws 1959, p. 1907.)