KINGSTON, Jamaica — The US Supreme Court ruled Friday that President Donald Trump did not have the authority to impose sweeping tariffs under a 1977 emergency powers law.

According to CNN, in a 6–3 decision, the court held that the International Emergency Economic Powers Act (IEEPA) does not authorise a president to levy tariffs, even during a declared national emergency.

Chief Justice John Roberts, writing for the majority, said Congress must clearly grant tariff authority and place careful limits on its use, something it did not do in IEEPA.

“When Congress grants the power to impose tariffs, it does so clearly and with careful constraints,” Roberts wrote. “It did neither here.”

Roberts emphasised that the court was not weighing economic policy or foreign affairs strategy, but rather fulfilling its constitutional role to interpret the law.

“We claim no special competence in matters of economics or foreign affairs,” he wrote. “We claim only … the limited role assigned to us by Article III of the Constitution.”

The ruling leaves unresolved what will happen to approximately $134 billion in tariffs collected by the federal government from more than 301,000 importers.

The majority opinion did not address whether the government must refund the money or how such repayments would be handled. That question will likely be decided by lower courts.

Justice Brett Kavanaugh criticised the majority for offering no guidance on refunds, writing that the process of returning billions of dollars could be a “mess.” Administration officials had warned that large-scale repayments could have serious economic consequences.

The case is one of the most consequential economic disputes to reach the court in years. It challenged Trump’s so-called “Liberation Day” tariffs, as well as steep duties imposed on imports from China, Mexico and Canada. Some tariffs reached as high as 145 per cent on Chinese goods.

Trump relied on IEEPA, a Cold War–era statute that allows presidents to “regulate … importation” during national emergencies. His administration argued that the term “regulate” plainly included the authority to impose tariffs. Challenging businesses countered that the words “tariff” and “duty” do not appear in the statute.

The decision aligns with a series of recent rulings limiting executive authority on major economic and political questions. In 2023, the court blocked a student loan forgiveness plan advanced by President Joe Biden, citing the so-called “major questions doctrine,” which requires clear congressional authorisation for sweeping policy changes.

Lower courts had unanimously ruled against Trump’s use of emergency tariff powers, including the United States Court of International Trade, which concluded that IEEPA did not authorise the duties.

Although the ruling curtails the use of emergency powers for tariffs, presidents retain other statutory authorities to impose trade barriers. Those alternatives, however, include time limits and procedural requirements that make them more constrained than the broad approach taken under IEEPA.

The immediate focus now turns to the practical question left unanswered by the high court: whether and how the federal government will return tens of billions of dollars already collected from American importers.

That process, as Kavanaugh warned, could prove complicated and costly.