Washington invoked Section 338 today, a rarely-used statute, in direct response to Canada's own countermeasures. It's the sharpest escalation yet in a dispute that's now run for most of the year.

The United States banned imports of a range of Canadian goods — including dairy products, motorcycles, and alcoholic beverages — effective today, September 29, invoking Section 338 of the Tariff Act of 1930. It's the first time the U.S. has expressly cited this statute to impose trade measures, and it marks a sharp escalation beyond the tariff-for-tariff exchanges that have defined the dispute since July.

How we got here

The dispute traces back to July, when President Trump announced 50% tariffs on a broad range of Canadian goods, citing what he described as discriminatory treatment of U.S. products. Those tariffs took effect August 22 after trade talks broke down days earlier. Canada matched them dollar-for-dollar with its own countermeasures on September 8, covering roughly $27.6 billion in U.S. imports across steel, dairy, appliances, agricultural equipment, pulp and paper, and electronics. Today's import ban is Washington's direct response to that Canadian retaliation.

Section 232 tariffs — the national security-based measures the U.S. has used on steel, aluminum, and autos — remain in place on top of this, and since September 15 the two sets of tariffs have been stacking rather than replacing one another.

What's actually banned

Unlike a tariff, which raises the cost of importing a good, a Section 338 ban prohibits importation outright — there's no price at which a U.S. buyer can still bring in the affected Canadian dairy products, motorcycles, or alcohol. For Canadian producers in those specific categories, this closes the U.S. market entirely rather than simply making it more expensive to access.

The bigger picture

Both countries' measures now apply even to goods that are CUSMA-compliant, and neither side's tariffs carry an expiry date — a marked departure from earlier rounds of this dispute, where measures were sometimes framed as temporary or tied to a specific negotiating deadline. With the U.S. also declining to renew USMCA when Canada and Mexico proposed doing so back in July, and bilateral rather than trilateral talks now the stated approach, there's no clear mechanism currently in place for de-escalation. For Canadian businesses in the newly banned categories, the practical question isn't how to absorb a higher cost anymore — it's finding alternative markets for products that can no longer legally enter the U.S. at all.