Meridian Analysis
What power did Trump actually use, and can Canada undo it by itself? Not easily. On 9 September, President Donald Trump signed five proclamations under Section 338 of the Tariff Act of 1930, a Depression-era law that lets a president bar the entry of goods from a country found to discriminate against US commerce. The bans cover most Canadian alcoholic beverages, whey, molasses and larger motorcycles, and take effect on 29 September. A separate set of changes to an existing tariff list, including the removal of cement and toilet paper from goods facing extra duties, takes effect on 15 September.
The White House says the bans answer Canada’s own retaliatory tariffs, which took effect just after midnight on 8 September on roughly $20 billion of US exports, including steel, dairy and agricultural equipment. Those Canadian tariffs followed the collapse of trade talks on 21 August, when Prime Minister Mark Carney, who leads the Canadian government, ended negotiations after calling US demands “uneconomic” and “unfair”.
Why does a 1930 law matter now?
Section 338 has sat largely unused for decades, overshadowed by newer trade tools built after the Second World War. It gives a president unusually direct authority: rather than raising tariffs, which still allow goods to cross the border at a cost, it lets the government block entry altogether. That is a sharper instrument than a tax, and one that does not require a finding from an independent agency or a vote in Congress. Trump had already applied Section 338 once this year, imposing tariffs on Canada in August; this second use goes further by cutting off the goods themselves.
The administration has paired the import bans with a procurement order: it has directed the General Services Administration, the federal agency that manages government purchasing, to strike Canadian-origin products from federal supply schedules covering more than $50 billion in spending. That means Canadian goods will not just face a harder time reaching US store shelves — they will be locked out of federal contracts as well.
What is actually being blocked, and why these products?
The list is narrower than “all Canadian goods.” It targets categories the White House and the US Trade Representative’s office, led by Jamieson Greer, have pointed to for months: alcohol, dairy-adjacent products such as whey, and motorcycles above a certain size. The choice tracks a long-running complaint from Washington that Canadian provinces discriminate against American alcohol. Canadian provinces began pulling US alcohol from shelves at the start of 2025, and the Distilled Spirits Council, a US trade association representing distillers, has said the dispute has already cut US spirits exports to Canada sharply. The same council supplies the trade data the US government cites on Canadian whisky sales into the American market, though the precise scale of that trade remains disputed enough that firm figures are not settled.
This is layered on top of tariffs already in place. The US had imposed 50% tariffs on about $20 billion of Canadian products — a slice of the roughly $382 billion in goods Canada sent to the US the previous year. The new bans do not replace those tariffs; they sit alongside them, closing off entirely a set of categories that were merely taxed before.
Who decides whether this holds, and who can push back?
Under Section 338, the decision to impose or lift the ban rests with the president alone. There is no independent review built into the mechanism, and no automatic sunset date beyond what the proclamations themselves specify. That concentration of authority is precisely what makes the tool attractive to an administration seeking to move quickly, and precisely what critics of executive trade power object to.
Canada’s options are narrower than they might appear. Dominic LeBlanc, the Canadian minister responsible for US trade relations, said on 9 September that Canada was still assessing the measures and remained open to negotiation. That points toward the likeliest route back from the current standoff: a resumed negotiation that could see both the US bans and Canada’s retaliatory tariffs unwound in parallel, rather than a legal challenge to Section 338 itself, which affords the president wide discretion.
Escalation is also visible outside the immediate ban list. Trump threatened Bombardier, the Canadian aerospace manufacturer, over the trade dispute on 7 September, two days before signing the proclamations — a sign the dispute is not confined to the named product categories and could widen further if talks do not resume.
What does not change on 29 September?
The bans apply to specified categories, not to Canada–US trade as a whole. Goods outside alcohol, whey, molasses and larger motorcycles continue to move under the tariff regime already in force, including the changes to the tariff list that took effect on 15 September, which removed some products such as cement and toilet paper from extra duties even as the administration added others. The result is not a blanket embargo but a targeted tightening, layered onto a trade relationship that has been hardening since Section 338 tariffs first went on in August.
What to watch next
The first hard test comes on 29 September, when the import bans take legal effect. Whether Canada has resumed substantive talks with Washington before that date, and whether either side moves to widen or narrow the list of affected goods, will show whether this is the peak of the dispute or another step in a longer escalation.