US Customs and Border Protection issues guidance on tariffs for Canadian goods

US Customs and Border Protection has begun rolling out guidance on a sweeping new tariff regime targeting Canadian goods, following three presidential proclamations issued on July 20, 2026. The agency is preparing to impose an additional 50% ad valorem duty on a wide range of Canadian products under Section 338 of the Tariff Act of 1930, a statute that has never before been deployed against Canada. The tariffs cover an estimated $20 billion in imports. Motor vehicles, alcoholic beverages, and dairy products bear the brunt of the action, which the White House says is a response to discriminatory trade practices by Ottawa that allegedly favor imports from other regions over American goods. What Section 338 actually does Section 338 is one of those dusty legal mechanisms that most trade lawyers thought would never see the light of day. Enacted as part of the Tariff Act of 1930, it grants the president authority to impose additional duties on goods from countries deemed to be discriminating against US commerce. The statute allows the president to levy duties of up to 50% on top of whatever tariffs already apply. These new duties stack onto existing tariffs and trade remedies, meaning s...