No Coverage For Failure To Warn Of TCE Contamination Plume

The Missouri Court of Appeals, applying Missouri law, held that insurers had no duty to defend or indemnify a defense contractor in connection with a class action alleging failure to warn of groundwater contamination. Certain Underwriters at Lloyd's London v. Northrop Grumman Corp., 2025 WL 3072808 (Mo. Ct. App. Nov. 4, 2025). The court affirmed summary judgment in favor of the insurers, finding that the underlying claims arose solely from conduct post-dating expiration of the relevant policies.

The coverage dispute arose after a class of Missouri property owners sued a company operating in the defense manufacturing sector for allegedly failing to disclose and remediate trichloroethylene ("TCE") contamination. The plaintiffs claimed, among other things, that the company failed to monitor the spread of TCE, negligently remediated the plume, and failed to warn the public of the spread, despite knowing of it since at least 2004. Ultimately, all causes of action were