Third-party complaints can be relied upon to establish a defense duty.

An Illinois Appellate Court applying Illinois law found that the trial court had properly relied on third-party complaints, rather than just the original complaint, in determining that a CGL insurer had a duty to defend where the third-party complaints were reviewed solely to determine whether there was a potential for the allegations to fall within the ambit of the insurance policy. The plaintiff sought coverage as an additional insured when one of its subcontractor’s employees filed a personal injury action. The policyholder sought a defense as an additional insured under the subcontractor’s policy, which didn’t provide coverage for direct acts of the policyholder. While the main complaint contained allegations of direct negligence against the policyholder, third-party complaints in the same action by other parties alleged liability as a result of the subcontractor’s acts. Considering the allegations as a whole, the court found a defense was owed due to the possibility that the policyholder could be held vicariously liable for the subcontractor’s acts. Illinois Emcasco Ins. Co. v. Waukegan Steel, No. 1-12-0735 (Ill. App. Ct. Sept. 13, 2013).