Sometimes called known loss, “anti-Montrose” provisions are typically found in an insurance policy’s insuring agreement and aim to collapse coverage for a continuing/progressive injury/damage into a single policy year. These provisions have been included since the 2001 revision of the Insurance Services Office (ISO) standard policy, (form CG 00 01).
The California Supreme Court’s seminal decision in Montrose Chemical Corporation v. Admiral Insurance Company was the impetus for the crafting of the language. In Montrose, the issue was whether a commercial general liability (CGL) carrier was obligated to defend lawsuits alleging continuous and progressive damage and injury resulting from hazardous chemicals the insured manufactured before and during the policy period at issue. The California Supreme Court answered the question in the affirmative, ruling that with respect to successive third-party liability policies, “bodily injury and property damage that is continuous or progressively deteriorating throughout several policy periods is potentially covered by all policies in effect during those periods.” In other words, the court ruled the “continuous injury” trigger applies to third-party liability cases involving continuous or progressively deteriorating losses.