Westfield Insurance Co. v. Sistersville Tank Works, Inc. (Signed Opinion)
Annotate this Case
The Supreme Court concluded that under the continuous-trigger theory, when an insurance claim is made by alleging a progressive injury caused by chemical exposure or other analogous toxic, injurious substance, damages that are caused, continuous, or progressively deteriorating throughout successive policy periods are covered by all the occurrence-based policies in effect during those periods.
This case involved claims against a standardized commercial general liability (CGL) policy alleging that long-term exposure to chemicals caused a disease to develop over a number of years before being diagnosed. The exposure to the chemicals and the development of the disease, however, happened across numerous CGL policy periods. Insurer denied coverage under its CGL policies and filed a complaint for declaratory relief. The district court granted a judgment in favor of Insured, finding that Insurer owed Insured a duty to defend and indemnify under all of its policies. The Supreme Court answered a certified question that, under the continuous-trigger theory, when a claim is made alleging a progressive injury caused by chemical exposure or other analogous harm, every occurrence-based policy in effect from the initial exposure, through the latency and development period and up to the manifestation of the bodily illness, is triggered and must cover the claim.
Some case metadata and case summaries were written with the help of AI, which can produce inaccuracies. You should read the full case before relying on it for legal research purposes.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.