US Supreme Court tariff ruling could deepen trade policy uncertainty

By Roland Paris

Published by Chatham House, February 22, 2026

The Supreme Court’s decision to invalidate Donald Trump’s emergency tariffs may have removed one instrument from his tariff toolkit, but it has done nothing to make US trade policy more predictable. If anything, it may herald even greater volatility.

Trump retains several alternative instruments now that tariffs imposed under the International Emergency Economic Powers Act (IEEPA) have been ruled unlawful. Each entails procedural hurdles, evidentiary thresholds, time limits and litigation risks. Yet, as Justice Brett Kavanaugh observed in his dissenting opinion, “the Court’s decision might not prevent Presidents from imposing most, if not all, of these same sorts of tariffs under other statutory authorities.”

That Trump, visibly angered by the ruling, quoted Kavanaugh’s statement not just once but twice suggests that he is not reconsidering his long-held belief in the benefits of tariffs. He has already pledged to introduce a new global tariff of 15 per cent, while signalling that further measures may follow.

For US trade partners – including several that negotiated agreements intended to reduce IEEPA tariffs on their exports – the outlook is unclear. The uncertain status of those arrangements, together with the prospect of new tariffs, now adds an additional layer of unpredictability to an already unstable picture.

Canada, for its part, gains little from the removal of the IEEPA tariffs, since goods compliant with the US–Mexico–Canada Agreement were already exempt. Meanwhile, the tariffs inflicting real pain on key Canadian sectors – including autos, steel, aluminium and lumber – remain in place because they rest on different statutory authorities. And any new US global tariffs may prove more damaging than the IEEPA measures if they eliminate existing exemptions.

The logic of Canadian prime minister Mark Carney’s speech at Davos, in other words, remains unchanged: the US is no longer a predictable or reliable partner, leaving its jilted allies with little choice but to diversify their trade partnerships and invest in their own resilience.

US Supreme Court tariff ruling could deepen trade policy uncertainty