The Supreme Court of the United States appeared to catch the president off-guard by ruling 6-3 that he cannot rely on the International Emergency Economic Powers Act (IEEPA) to impose sweeping tariffs.

In a lengthy judgment handed down on Friday, the court said: “The president asserts the extraordinary power to unilaterally impose tariffs of unlimited amount, duration, and scope. In light of the breadth, history, and constitutional context of that asserted authority, he must identify clear congressional authorisation to exercise it.

“IEEPA’s grant of authority to ‘regulate… importation’ falls short. IEEPA contains no reference to tariffs or duties. The government points to no statute in which Congress used the word ‘regulate’ to authorise taxation. And until now no President has read IEEPA to confer such power.

“We claim no special competence in matters of economics or foreign affairs. We claim only, as we must, the limited role assigned to us by Article III of the Constitution. Fulfilling that role, we hold that IEEPA does not authorise the president to impose tariffs.”

In a statement yesterday, the European Commission said the EU “expects the US to honour its commitments” set out in the EU-EU joint statement of August 2025.

“In particular, EU products must continue to benefit from the most competitive treatment, with no increases in tariffs beyond the clear and all-inclusive ceiling previously agreed,” it said.

“Tariffs are taxes, driving up costs for both consumers and businesses, as recent studies clearly confirm.

“When applied unpredictably, tariffs are inherently disruptive, undermining confidence and stability across global markets and creating further uncertainty across international supply chains.”

Ireland’s foreign affairs and trade minister, Helen McEntee, said on Friday: “I note today’s US Supreme Court ruling on US tariffs. The decision focuses on whether the US Administration may have exceeded presidential authority when it imposed broad import duties under the 1977 International Emergency Economic Powers Act (IEEPA).

“While the ruling does not affect tariffs introduced under other legal bases, including Section 232 of the Trade Expansion Act, it is a significant development in the wider global trading environment.

“Open, stable and predictable trade remains essential for economic growth, investment and jobs in Ireland.

“I remain in close contact with the European Commission on this issue. I understand they are engaging directly with the US administration to seek clarity on how they intend to respond.

“My Department will continue to monitor developments closely and assess any potential implications for Irish trade, businesses and jobs.”