The Justice Department disputes an importer’s claim at the U.S. Court of International Trade that changes to the de minimis tariff exception cannot be made by executive action alone, arguing that the International Emergency Economic Powers Act authorizes the president to override “privileges” created by other statutes. Detroit Axle, a Michigan company that sells Chinese-made auto parts, in May sued the Trump administration after it ended de minimis benefits for goods from China valued at $800 or less. The company...