Under a 94-Year-Old Law, Trump Hits Canada with 50% Duties

Section 338 of the Tariff Act of 1930 has mostly sat untouched for its entire existence. On Monday, President Trump signed three proclamations invoking it anyway, imposing 50 percent tariffs on a wide range of Canadian imports.^[1] The move escalates a trade dispute with America's largest trading partner and reaches for a legal authority modern presidents have barely touched.

According to the White House, Canada's own retaliatory measures triggered this response,^[2] specifically Canadian boycotts of American alcohol and dairy that followed earlier rounds of U.S. tariffs on Canadian goods. Administration officials describe the new duties as leveling the field for American producers. "President Trump is offsetting the burden and disadvantage on U.S. commerce from Canada's discriminatory treatment," the White House fact sheet reads.

The list of goods affected runs long: dairy products, alcohol, wine, hockey sticks, cement, construction materials, clothing, furniture, technology products. Three separate proclamations exist because each one covers a different category. Thirty days from signing, the tariffs take effect.

Section 338 lets the president impose duties on countries found to be discriminating against U.S. commerce, and it dates back to 1930, part of the Smoot-Hawley Tariff Act, the same legislation widely blamed for deepening the Great Depression by setting off retaliatory tariffs from trading partners around the world. Built as a retaliation tool from the start, Section 338 has been left alone by successive administrations, who reached instead for more modern authorities under Sections 201, 232, and 301 of later trade laws.

Reaching for it now says something beyond trade policy. It signals a willingness to use legal tools considered too blunt, or too risky, for ordinary disputes, and it suggests the administration views the relationship with Canada as having deteriorated past the point where those old constraints still apply.

Canada hasn't formally responded yet, though officials are expected to weigh in within days.^[3] The two countries have been locked in an escalating cycle of tariffs and counter-tariffs since early in Trump's second term, with every round drawing some retaliation from Ottawa. Should Canada answer these new 50 percent duties with measures of its own, the next rung on this ladder gets steep fast.

Real money is at stake here. Canada ranks as the top U.S. trading partner by volume, and the goods named in these proclamations feed directly into American construction and manufacturing supply chains. Cement and lumber touch housing costs. Technology tariffs ripple through electronics supply chains. Canadian dairy and agricultural producers, already dealing with earlier tariff rounds, now face another 50 percent wall on top of it.

American companies that depend on Canadian materials will feel this too. Tariffs get paid by the importer, not the foreign government, a fact that tends to get lost in the political noise around announcements like this one. Businesses bringing in Canadian construction materials will face higher costs, and they'll either eat those costs or pass them along.

Trade lawyers see the 30-day window before tariffs kick in as deliberate. It leaves room for diplomacy, or, put more cynically, room for Canada to make concessions before the duties land. How Ottawa reads that window, and whether it speeds up its own retaliatory planning instead, will shape what August looks like.

Legal questions hang over all of this too. Trade authority scholars note that Section 338 has never faced a real test in modern federal courts, and its scope and procedural rules are far less defined than newer trade statutes. A legal challenge from Canadian companies or importers hit by the tariffs isn't out of the question.

For now, these tariffs stand as the most aggressive unilateral move the administration has made against Canada this term. Thirty days, and counting.

This article was researched, drafted, and edited with the assistance of Claude (Anthropic) via the Cowork platform. The Nautisk discloses AI assistance in its content production in accordance with editorial standards and the NY FAIR News Act.