Donald Trump signed an executive order on Monday to impose a 50% tariff on most imports from Canada, marking one of the most aggressive protectionist measures of his second term against a historical ally.
The new taxes will come into effect on August 19, 30 days after the presidential proclamation.
“They need us to survive. Without us, there is no way they can survive,” replied the president when questioned on the topic.
The measure not only strains the bilateral relationship between Washington and Ottawa but also sends a direct warning to the rest of the world: no trading partner of the United States is safe from a similar tariff escalation.
The legal basis: A regulation from 1930 never before used
To justify the tariffs, the Trump administration turned to the Section 338 of the Tariff Act of 1930, a little-known provision that allows the president to impose duties of up to 50% when another country discriminates against American products.
This rule had never been used for that purpose, which opens the door to possible legal challenges, but it also represents a new legal avenue following the setback Trump experienced in the Supreme Court, which in February 2026 overturned his broad tariffs based on emergency powers.
According to economist Stephen Brown from Capital Economics, the government may be testing whether this law "could be used to impose tariffs on other countries in the future."
Experts from the Cato Institute had already warned that the statute could be "susceptible to abuse by a protectionist government."
What products are affected?
The new tariffs are added to the general rate of 10% that Trump imposed in February 2026, increasing the total burden on many Canadian products.
Energy, potash, critical minerals, and fish are excluded.
However, the measure covers goods that have so far been protected by the treaty between Mexico, the United States, and Canada (USMCA), such as automobiles, dairy products, wine, cement, and hockey sticks.
In addition, goods diverted through third countries to evade tariffs will be subject to an additional levy of 40%.
The justification of Washington
The White House claimed that Canada maintains "harmful" trade practices for the United States: restrictions on access to dairy products, high tariffs on agricultural goods, taxes on digital services, and previous trade retaliations.
The U.S. Commercial Representative, Jamieson Greer, summarized it in an interview with CNBC: “We have a tariff that is, again, a natural consequence of Canada’s retaliations.”
Although Trump had threatened Canada last Friday on Truth Social with new tariffs due to the smoke from wildfires in Manitoba, Saskatchewan, and Ontario, the White House ultimately justified the decision in strictly commercial terms.
The response from Ottawa
The Canadian Prime Minister, Mark Carney, accused Washington of violating the USMCA.
“This is the latest in a series of unilateral trade actions by the United States that began with the imposition of a series of tariffs in direct violation of the Agreement between Canada, the United States, and Mexico,” it stated in a release, according to the EFE agency.
Carney left the door open for negotiations: "Canada has put forward a series of detailed and comprehensive proposals to resolve this dispute and modernize the CUSMA. We are prepared to intensify those conversations in the coming weeks."
A warning for the entire world
What is at stake goes beyond the bilateral dispute.
According to CNN, if the government manages to broadly define what constitutes "discrimination" against American products, it would have a new legal avenue to impose high tariffs on any country whose policies it deems unacceptable.
This escalation occurs after Trump's refusal to renew the T-MEC in its current format on July 2, when he opted for a mechanism of annual reviews until 2036.
The treaty facilitates approximately two trillion dollars in annual trade among the three countries.
The trade attorney Greg Husisian from the firm Foley & Lardner was straightforward:
"Other countries will continue to have to take this kind of threat seriously. This confirms that President Trump will keep using the threat of tariffs to achieve foreign policy objectives for the remainder of his presidency."
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