Illinois is a "four corners" state in which determining a duty to defend relies totally upon the wording of the lawsuit and the policy. No facts extrinsic to the pleadings or the policy wording are allowed to impinge upon the court's analysis of the duty to defend. This rule, followed in several states, often results in rulings that put defendants and their insurers at the mercy of the plaintiff pleading a lawsuit against the defendant.

A plaintiff can instruct his lawyers to plead the lawsuit in terms of intentional tort—assault, battery, trespass, etc.— rather than negligence. Thus, reviewing the four corners of the lawsuit and the policy, the insured can never receive defense from its insurer whose policy would not include coverage for intentional acts. Similarly, a plaintiff's lawyer whose client was injured by an intentional tort will plead a suit against the aggressor in terms of negligence so that the aggressor's insurer will defend and eventually indemnify the aggressor.

In Landmark American Insurance Co. v. O'Malley, 2014 WL 2978213 (N.D.Ill.), Landmark sued insurance brokers Michael O'Malley, O'M and Associates LLC and Peter Hilger, seeking a declaration that Landmark has no duty to defend them in two underlying lawsuits, one in Michigan and one in Tennessee, and the defendants responded with an opposite motion.