President Donald Trump has identified a new Canadian export to tariff: wildfire smoke.
In a July 17 post to Truth Social, Trump accused Canada of “Willful Negligence” for failing to maintain its forests and said the “incalculable” cost of smoke entering the United States should be added to tariffs. He renewed the threat days later, vowing tariffs in retaliation for the smoke drifting south.
Meanwhile, on July 20, Republican Sen. Bernie Moreno introduced the CANADA FIRE Act. If passed, it could be used to impose sanctions, visa restrictions and limits on government dealings with Canada.
Such measures raise questions about whether the United States can seek compensation for Canada’s wildfires under trade rules or other laws.
John Boscariol, a partner specializing in trade law at law firm McCarthy Tétrault, says trade measures are not intended to deal with something like wildfires.
“I’m not aware of an existing tariff authority in the United States that would allow the U.S. administration to impose tariffs on the basis of smoke drifting over from Canada,” he said.
“It’s absolutely far-fetched for the Trump administration to say, ‘We’ll impose tariffs because of the forest-fire smoke,’” he said. “But unfortunately, it’s not surprising.”
On July 20, the Trump administration did impose new 50-per-cent tariffs on a wide range of Canadian products — including wine, hockey sticks and cement — beginning Aug. 19.
But Alexander Hobbs, an international trade lawyer at the law firm Cassidy Levy Kent, notes these tariffs have been invoked on different grounds.
“The White House has specifically stated that this is not related to the wildfires,” said Hobbs.
The White House says its new tariffs — invoked under the Tariff Act of 1930 — are a response to Canada’s allegedly discriminatory treatment of American vehicles, alcohol and dairy products.
“The United States is alleging that the tariff-rate quotas under the CUSMA are not as favourable … as under the Comprehensive Economic and Trade Agreement (CETA),” said Hobbs, referencing Canada’s free trade deal with Europe.
Transboundary liability
The Trump administration could look for other ways to seek compensation for wildfire-related costs.
But Michael Gerrard, founder and faculty director of Columbia University’s Sabin Center for Climate Change Law, says it would be difficult to succeed under international law.
“There is no plausible theory under existing international law whereby the U.S. could hold Canada legally liable for wildfire smoke,” he said.
In the late 1930s, the Canadian government was ordered to pay the U.S. government US$78,000 after an international tribunal ruled that noxious fumes from a private, B.C.-based smelter had damaged property in Washington state.
That case helped establish the principle that states should not permit activities within their territory that cause serious environmental harm elsewhere, says Gerrard. But that case involved a single industrial facility, quantifiable damage and two countries that had agreed to arbitration.
Canada and the United States would both need to consent to any new arbitration.
Separately, sovereign immunity — an international legal principle codified in U.S. law — generally prevents countries from being sued in U.S. courts without their consent.
Canada and the U.S. are parties to the 1991 Canada-U.S. Air Quality Agreement, which imposes pollution targets for certain gases, including sulphur dioxide and nitrogen oxides linked to acid rain. But it does not include any commitments regarding wildfire particulate.
Canada and the U.S. also have a 2023 arrangement facilitating the exchange of firefighting resources and information. This arrangement is focused on co-operation, however, not compensation.
The management myth
The larger question at play is whether Canada is capable of preventing wildfires through better forest management and firefighting practices.
Lori Daniels, a forest ecologist at the University of British Columbia, says more than half of Canada’s forests are not actively managed. Suppressing every remote fire is impossible during hot, dry and windy conditions.
Natural Resources Canada counts 369 million hectares of forest, much of it remote boreal terrain without year-round road access. Historical data show lightning starts about 46 per cent of Canadian forest fires but accounts for approximately 83 per cent of the area burned.
The Ontario fires that produced much of the smoke that affected the U.S. are burning in spruce and pine forests over organic, moss-rich soils.
Thinning techniques — such as removing small trees and brush to reduce fire risk — can work in the drier forests of western North America, says Daniels. But applying it indiscriminately can open the canopy, admit more sunlight, dry moss and increase wind.
“That can actually make the fires worse,” she said.
However, fire management efforts still have an important role to play near communities. Daniels says increasing broadleaf trees can slow fire spread, while prescribed burning can make some populated areas and transportation corridors more resilient.
Daniels also notes that fires in Alaska and the western U.S. regularly send smoke into Canada, just as Canadian smoke travels south.
The practical response, says Daniels, is is neither to seek damages nor to fireproof entire boreal forests.
“I really think the solutions are to continue working towards adaptive management, sharing information across the border so that we can all improve and be prepared for future fires,” she said.
