Donald Trump's new forced-labour tariffs hit Canada at 10% today, slapping 60 trading partners just as a temporary 10% global levy expired — and this is the smaller of Ottawa's problems. The real hammer drops Aug. 19, when 50% tariffs on roughly $20 billion of Canadian goods — hockey gear, beer, dairy, cement, electrical equipment — take effect under Section 338 of the Smoot-Hawley Tariff Act of 1930, a Depression-era law never before invoked. Prime Minister...