Trump Vows 50% Tariff on Canadian Goods Using A Depression-Era Law

On Monday, July 20, 2026, President Trump signed three proclamations imposing an additional 50% ad valorem tariff on roughly $20 billion of Canadian imports, effective 12:01 a.m. ET on August 19, 2026 (30 days out). This further inflames trade tensions between the two neighbours.

The novel feature is the legal authority. The administration invoked Section 338 of the Tariff Act of 1930. This never-before-used provision lets a president impose duties of up to 50% on a country found to be discriminating against U.S. commerce, without congressional approval. Cato’s Scott Lincicome called it “the nuclear option for Trump tariffs,” noting, “we crossed the Rubicon.” This matters because the Supreme Court struck down Trump’s earlier IEEPA-based emergency tariffs, but Section 338 has never been litigated — so its legal durability is untested.

Why they’re doing it

The stated rationale is retaliation for three specific Canadian “discriminatory” measures against U.S. exports:

• Alcohol — some provinces pulled U.S. alcohol products off Canadian shelves.
• Dairy — Canada gave better market access to EU dairy than to U.S. dairy (the supply-management quota issue).
• Motor vehicles — Canada maintained a 25% tariff on U.S. vehicles not eligible for CUSMA duty-free treatment and capped U.S. vehicle exports from reshoring automakers. The proclamation notes Canadian imports of U.S. vehicles fell ~22% (roughly US$25.9B to US$20.3B year-over-year) under that scheme.
• Goods covered by separate duties on industries, including autos and steel, will also be spared.

A senior official framed it as holding Canada “accountable” for being one of the only countries — alongside China — to retaliate substantially against earlier U.S. tariffs. The timing is pointed: it lands the day before U.S., Canadian and Mexican officials were to meet in Mexico on CUSMA, and a week before the opening of the Gordie Howe Bridge.

Sectors most affected

Despite being triggered by autos/alcohol/dairy, the covered product list is very broad and hits many consumer and industrial goods:

• Alcohol and dairy: wine, liquor, milk products
• Building materials: cement, plywood
• Consumer goods: clothing, furniture, footwear (hockey skates/sticks), cut flowers and bulbs, diaries and notebooks
• Machinery, electrical equipment (e.g., refrigeration), and some food products and technology

Key exemptions: energy products, potash, fish, and critical minerals are carved out. The new 50% duty also does not stack on goods already covered by Section 232 tariffs (autos, steel, aluminum), so it’s additive to the existing tariff wall rather than doubling it on those sectors.

How it fits with USMCA/CUSMA

Crucially, for the items on the new tariff list, there will be no exemptions for exporters shipping under the rules of the existing North American trade pact between the US, Canada and Mexico. The Office of the US Trade Representative estimated that $20 billion in imports — about 5% of total Canadian goods sent to the US last year — would be hit. Overriding the protections under CUS is a significant escalation.

The context: at the mandatory six-year joint review on July 1, 2026, the US declined to renew CUSMA in its current form (Canada and Mexico both wanted a 16-year extension). That didn’t terminate the agreement — it remains legally in force through 2036 unless a party withdraws with six months’ notice — but it pushed the deal into a rolling annual review cycle, which analysts are calling a “zombie USMCA”.

PM Carney’s response was to call this “the latest in a series of unilateral U.S. trade actions… in direct violation of CUSMA”, stressing that Canada has “merely matched” the US auto tariffs as is its right, while signalling Canada has made detailed proposals to modernize CUSMA and stands “ready to intensify those discussions in the coming weeks”. So both the legal basis (Section 338 as a domestic workaround) and the CUSMA-override design suggest that the US is using tariffs as leverage in the annual review process rather than treating CUSMA obligations as binding. Given the 30-day runway to August 19, this reads as much as a negotiating instrument as a fixed policy — there’s a clear window for a deal before it bites. The president has made such threats before, only to pull back after negotiations or because of market concerns.

As quoted in Bloomberg News, “This is definitely a big escalation. We always knew that things would probably get worse before they got better,” said William Pellerin, an international trade lawyer based in Canada at McMillan LLP. “With respect to the United States, every time we get close to a deal or things look like they might be settling in, the temperature gets raised.”

Bottom Line

Monday’s action threatens to further strain relations with Canadian Prime Minister Mark Carney, who joined Trump to view the World Cup final in New Jersey on Sunday. Last week, Trump threatened to impose higher tariffs to punish Canada for the wildfire smoke that blanketed US cities, including New York and Washington.