( September 9, 2025, 2:56 PM EDT) -- BOSTON — The First Circuit U.S. Court of Appeals on Sept. 8 affirmed a lower federal court’s ruling that a commercial general liability and umbrella insurer has a duty to defend its insured against an underlying customer class action alleging that the insured caused harm by adding biodiesel fuel to its home heating oil in proportions that exceeded industry standards, rejecting the insurer’s argument that the known loss and loss-in-progress policy provisions relieve it of its duty to defend....