Montrose Chem. Corp. v. Superior Court of State

*1312 Petitioner Montrose Chemical Corporation of California (Montrose) for many years manufactured the pesticide dichloro-diphenyl-trichlorethane (DDT). Real parties in interest are insurers that issued excess comprehensive general liability (CGL) policies to Montrose in relevant years. The present dispute concerns the sequence in which Montrose may access its excess CGL policies to cover its liability for environmental injuries caused by DDT.

Through a motion for summary adjudication, Montrose sought a declaratory judgment that it may "electively stack" excess policies-i.e., that it may access any excess policy issued in any policy year so long as the lower-lying policies for the same policy year have been exhausted. All of the excess insurers opposed Montrose's motion for summary adjudication; many of the excess insurers also sought through a cross-motion for summary adjudication a ruling that no insurer had a duty to pay a covered claim until Montrose had "horizontally exhausted" its lower-lying excess policies in all triggered policy years.

The trial court rejected "elective stacking" in favor of "horizontal exhaustion," ordering that higher-level excess policies could not…