Trump Revives the 1930 Smoot-Hawley Tariff Act for Canada — After SCOTUS Narrows His IEEPA Authority

With the Supreme Court narrowing his tariff powers under IEEPA and the temporary tariff stopgap expiring, President Trump is turning to a 95-year-old provision of the 1930 Smoot-Hawley Tariff Act to impose additional tariffs on Canada. It is the most consequential invocation of that authority since the interwar period.

The Trump administration is reaching back to 1930 for legal authority. According to reporting synthesized by Axios in mid-July, President Trump is invoking a rarely used discretionary provision of the Smoot-Hawley Tariff Act to impose additional tariffs on Canada, framing the move as a response to alleged Canadian discrimination against US exports. The White House has not yet published the underlying determination in the Federal Register, but Cabinet-level statements this week have made the intent explicit.

The choice of legal instrument is what makes the move consequential beyond the immediate US-Canada dispute. Since 2017, the administration favored Section 232 (national security) and, more recently, Section 122 and IEEPA (International Emergency Economic Powers Act). Recent Supreme Court decisions have narrowed the executive IEEPA-based tariff powers, and a temporary tariff stopgap authority is expiring. Smoot-Hawley discretionary retaliation provision — unused in any serious form for decades — provides a new legal foothold that has not yet been directly tested in court under modern administrative law standards.

The bilateral implications are immediate. Canada is the largest single trading partner of the United States, and USMCA (the successor to NAFTA) is now under stress it was not designed to bear. Ottawa has previously matched US tariff actions with proportional retaliation; whether Canada does so this time will depend in part on whether the political calculus in Ottawa reads the Smoot-Hawley invocation as a durable strategic shift or a negotiating move. Pew polling reported by Axios in late June found the share of Canadians describing the United States as a reliable partner has fallen from 83% in 2022 to 35% today — a shift that constrains what any Canadian government can politically absorb.

The broader question is one of legal architecture. Congressional tariff authority under Article I was delegated to the executive incrementally over nine decades. The recent Supreme Court narrowing of IEEPA, combined with expiring stopgaps and the reach back to Smoot-Hawley, suggests the administration is testing what authority remains and how far it can be stretched. Legal challenges are likely; the outcomes will determine what tariff tools any future president — of either party — retains.

For federal contractors and firms with cross-border supply chains, the immediate practical consequence is planning uncertainty. Tariff schedules built around IEEPA-based orders may be superseded by Smoot-Hawley-based orders with different rates, different affected categories, and different enforcement postures. The interagency guidance has lagged the executive action — a pattern that has characterized much of the second administration trade policy. In the interim, companies with material Canadian sourcing or export exposure should treat the current environment as durably unstable rather than transitional.

Sources: Axios — Top July 17 (Smoot-Hawley invocation) · Axios — Trump foreign policy sinks US trust (Pew) · FDD — Trump Foreign Policy Tracker · Axios — Politics & Policy