Coverage disputes between primary liability insurers and excess liability insurers over multiple-vehicle accidents often boil down to a question of simple math: Was there just one accident, which triggers excess coverage, or were there multiple accidents, which usually places the responsibility for coverage with the primary insurer?

Dallas attorney R. Brent Cooper recently took that math question to the U.S. Court of Appeals for the Fifth Circuit on behalf of a primary liability insurer in a dispute over a serious multi-vehicle accident, and they agreed with his argument that it was a single incident—a ruling that saved his client more than $1 million.

Cooper represents Mid-Continent Casualty Co., a primary insurer that was sued by excess liability insurer Evanston Insurance Co. in a coverage dispute over the number of accidents that took place under an insurance policy.