• The US Supreme Court ruled 6–3 that President Donald Trump unlawfully used the International Emergency Economic Powers Act (IEEPA) to impose sweeping tariffs, holding that the statute does not authorise the unilateral levying of trade duties.
• The decision invalidates key elements of Trump’s tariff programme — including country-specific “reciprocal” tariffs and certain 25 percent duties linked to fentanyl concerns — while leaving in place measures enacted under separate trade laws, such as steel and aluminium tariffs.
• Trump criticised the ruling and signalled plans to introduce new tariffs under alternative legal authorities, as businesses welcomed the judgment and calls mounted for refunds of billions of US$ collected under the now-struck-down measures.

The US Supreme Court handed President Donald Trump a significant legal defeat on Friday, ruling that he overstepped his authority by using emergency powers legislation to impose broad tariffs on imports.

In a 6–3 decision, the justices concluded that the 1977 International Emergency Economic Powers Act (IEEPA) does not grant a president the power to levy tariffs. The judgment nullifies a substantial portion of the trade duties introduced under Trump’s second term, though several measures enacted under different statutes remain intact.

Delivering the majority opinion, Chief Justice John Roberts wrote that the president had claimed “extraordinary power” to impose tariffs without limit as to scale or duration. However, he noted that the administration failed to identify any statutory basis demonstrating that Congress intended IEEPA to authorise such measures. The court therefore determined that the law does not permit the unilateral imposition of tariffs.

Roberts was joined by the court’s three liberal members as well as conservative justices Neil Gorsuch and Amy Coney Barrett. In dissent were Clarence Thomas, Brett Kavanaugh and Samuel Alito.

Reacting at the White House, Trump denounced the ruling as a “disgrace”, accusing the majority of acting in a manner he described as unpatriotic and suggesting they had been influenced by foreign interests. He signalled that he would pivot to alternative statutory authorities to reintroduce duties, announcing plans for a 10 percent global tariff, which he characterised as lower than the current rates imposed on most countries.

Financial markets responded positively to the judgment, with shares rising despite the president’s insistence that his tariff regime had bolstered the economy.

The decision leaves untouched certain sector-specific duties, including tariffs on steel and aluminium imposed under different trade laws. However, it dismantles two central pillars of Trump’s broader trade programme: country-specific “reciprocal” tariffs, ranging from 34 percent on China to a 10 percent baseline for many other nations, and a 25 percent duty on selected imports from Canada, China and Mexico introduced in response to what the administration described as inadequate efforts to curb fentanyl trafficking.

Businesses that challenged the measures welcomed the outcome. Victor Schwartz, head of New York wine and spirits importer VOS Selections, said the tariffs had been “arbitrary” and harmful to commercial stability. He added that the judiciary had consistently recognised the duties as unconstitutional overreach.

Importers that paid the now-invalidated tariffs may seek reimbursement from the Treasury Department. While the court did not provide guidance on how refunds should be handled, Kavanaugh, writing in dissent, observed that the fiscal implications for the federal government could be substantial. He also suggested that the ruling would not significantly curtail presidential tariff powers beyond the specific context of IEEPA.

Advocacy group We Pay the Tariffs called for a swift and automatic refund mechanism, arguing that small firms could not endure prolonged administrative delays or costly litigation simply to recover sums unlawfully collected.

Under the US Constitution, the authority to set tariffs rests with Congress. IEEPA permits a president to regulate imports and exports during a declared national emergency arising from an unusual and extraordinary threat, but it makes no explicit reference to tariffs. Prior to Trump, no president had relied on the statute to impose them.

The case consolidated two lower court rulings that had found against the administration. It also revived debate over the so-called “major questions doctrine”, previously invoked by the court when it struck down former President Joe Biden’s student loan forgiveness plan. In Friday’s judgment, Roberts referenced the doctrine, although that portion of his reasoning did not command a majority. The court’s liberal justices, who had earlier dissented in the student loan case, agreed the tariffs were unlawful but on different grounds.

Several companies joined the legal challenge, including Plastic Services and Products, which manufactures pipes and fittings, and two educational toy retailers. A coalition of states led by Oregon also brought suit.

According to US Customs and Border Protection data, tariffs imposed under IEEPA had generated roughly US$130 billion by mid-December. Trump has claimed far higher figures, citing projected gains from trade agreements negotiated by his administration.