For years, when faced with damage or injury spanning several policy periods, excess general liability insurers have argued that all potentially applicable underlying policies must be exhausted before the excess drops down to provide coverage (“horizontal exhaustion”). Insureds, on the other hand, insist that they are entitled to immediately access an excess policy for any given policy year, if that year’s underlying policy has exhausted (“vertical exhaustion”). Vertical exhaustion not only enables insureds to directly tap into the excess insurance for which they paid substantial premiums, but also enables the insured to moderate risk given that different lower level policies might (1) be needed for other claims, (2) have larger self-insured retentions, or (3) have other less favorable coverage provisions. Allowing an insured to proceed via vertical exhaustion would also eliminate the heavy administrative and logistical burden that could result from having to pursue and exhaust all underlying coverage on multi-year claims.
In Montrose Chemical Corp. v. Superior Court, 2020 WL 1671560 (April 6, 2020), the California Supreme Court has come down in favor of policyholders and vertical exhaustion. The Montrose case involved contamination that allegedly occurred between 1947 and 1982 and different liability insurance towers (comprised of primary and excess layers) for each year. The insured, Montrose, maintained a tower of insurance coverage, year by year, and faced claims asserting damage that spanned several decades. Montrose sought coverage from excess insurers under a vertical exhaustion approach. Not surprisingly, Montrose’s excess insurers insisted that horizontal exclusion was required and that Montrose was required to exhausted all other policies with lower attachment points in every single involved policy period. The California Supreme Court ruled in Montrose’s favor, holding that the insured may insist upon full coverage from an excess insurer once the layer directly below it has exhausted. The Court reasoned that the burden of spreading the loss among insurers is one that is appropriately borne by insurers, not insureds.