(February 11, 2016, 2:33 PM EST) -- PORTLAND, Maine — An umbrella insurer has a duty to defend its insured against two environmental contamination suits under certain of its policies; however, the insured must prove that it exhausted the underlying policy limits before the remaining policies may be triggered, a Maine justice said Feb. 9 (Irving Oil Limited v. ACE INA Insurance, No. 09-35, Maine Business, Cumberland Co.)....