A presidency by tariff

When Donald Trump once again reached for tariffs, he did so with familiar language and an unfamiliar legal theory.

The stated goals were sweeping. He pointed to illegal drugs flowing from Canada, Mexico and China. He spoke of “large and persistent” trade deficits that had hollowed out American manufacturing. He declared national emergencies. And then, invoking the International Emergency Economic Powers Act, or IEEPA, he imposed tariffs across a wide swath of imports—duties of 25% on most Canadian and Mexican goods, 10% on Chinese imports that later rose dramatically, and a baseline tariff of at least 10% on goods from virtually all trading partners.