What Is Section 338, the Depression-Era Law Trump Is Using to Tariff Canada?

The Trump administration announced, delayed, and then enacted 50 percent tariffs in August against an estimated $20 billion worth of goods coming from Canada, citing Section 338 as its authority for doing so.
The White House said on its website that “Canada has been ripping off the United States for decades—and President Donald J. Trump is done letting them get away with it.”
Canadian Prime Minister Mark Carney said on Aug. 22, “We are walking away from a bad deal.”
Carney pledged that his nation would “match Washington’s new tariffs dollar for dollar in order to protect Canadian workers, farmers, families, and businesses.”…