Law360, New York (November 23, 2015, 12:52 PM EST) -- Excess insurance policies supply coverage above underlying limits provided by primary insurance and "attach," or become liable to pay a covered claim, once the layer(s) of insurance below have been exhausted. This sounds simple enough. However, different courts have reached different opinions as to what constitutes "exhaustion" of a primary policy for purposes of triggering excess coverage. Some courts, absent explicit policy language to the contrary, consider primary coverage exhausted as long as the insured's liability is greater than the primary policy limits. Other courts do not consider a primary policy exhausted unless the primary insurer has paid out its full policy limits to the insured. The result seems to depend in part on whether there is a perceived ambiguity in how the excess policy defines "exhaustion" and in part on the court's approach to the intersection between insurance contract interpretation and public policy concerns. The outcome of a lawsuit over excess policy coverage may depend, not only on the language of the policy itself, but on where the action takes place....