Trump Invokes a Dormant 1930 Law to Hit Canada With 50% Tariffs on Autos, Alcohol and Dairy

A Tariff Law Nobody Had Ever Actually Used

Section 338 of the Tariff Act of 1930 empowers the president to impose duties of up to 50% on goods from a country found to discriminate against US commerce. It has been on the books since the Smoot-Hawley era — the tariff package historians blame for deepening the Great Depression by triggering a wave of retaliatory tariffs worldwide — but no administration had ever actually used it to impose a tariff before this month, despite it being considered and threatened at various points, including against France in the 1930s and reportedly discussed as a lever against Japan in the late 1930s. President Trump's July 20 proclamations against Canada mark its first confirmed use for an actual tariff.

Three Separate Proclamations, One Target

Rather than a single blanket order, the White House issued three distinct Section 338 proclamations on July 20, 2026, each targeting a specific Canadian export category: motor vehicles, alcoholic beverages, and dairy products. Each imposes an additional 50% duty on top of existing tariffs. The White House and USTR describe the action as covering close to $20 billion in annual Canadian exports to the US.

The Administration's Case

In his statement, Ambassador Greer laid out three specific grievances: Canada has taken US alcohol products off Canadian retail shelves; Canada has given European Union dairy exporters better market access than US dairy exporters receive; and Canada has capped vehicle exports to Canada from US automakers that have reshored production to the United States. Greer characterized these as discriminatory measures that justify using Section 338's offsetting-duty authority, which is written into law specifically to let the president respond to a foreign country's unequal treatment of US commerce without needing a new act of Congress.

Landing in the Middle of a Bigger Tariff Reset

The Canada action did not happen in isolation. It landed on July 20, just days before two other major US tariff tracks reached their own turning points: the Section 122 global 10% tariff — a separate presidential authority capped by law at 150 days — expired automatically at 12:01 a.m. on July 24, 2026, and a new set of Section 301 tariffs (10% to 12.5%) tied to a forced-labor enforcement investigation, announced July 23, took effect on 60 economies plus the EU on July 24. Trade lawyers tracking the overall tariff picture describe Section 338 as functionally different from both: unlike Section 122, it has no 150-day statutory cap, and unlike Section 301, it does not require a lengthy investigation process before being invoked, since it is designed as a direct response to a specific instance of discriminatory treatment.

What Comes Next

The tariffs are scheduled to take effect on August 19, 2026, giving Canadian exporters and US importers roughly a month's notice. Canada had not announced a retaliatory response as of this writing. Because Section 338 has never been tested, its durability against a future legal challenge — similar to the one that reached the Supreme Court over broader tariff authority earlier this year — is untested, though its narrower, discrimination-specific design may make it harder to challenge than the broader emergency powers used under Section 122.