Washington: The US Supreme Court ruled on Friday that Donald Trump overstepped his authority in imposing a broad range of tariffs that disrupted global trade, striking down a key tool the former president had used to advance his economic agenda.

In a 6-3 decision, the conservative-majority court said the International Emergency Economic Powers Act (IEEPA) "does not authorise the President to impose tariffs."

While Trump has long used tariffs as a bargaining tool, he made unprecedented use of emergency economic powers last year to impose new duties on nearly all US trading partners.

These included “reciprocal” tariffs aimed at trade practices Washington deemed unfair, as well as separate duties targeting major partners Mexico, Canada and China over issues such as illicit drug flows and immigration.

The court noted that "had Congress intended to convey the distinct and extraordinary power to impose tariffs" under IEEPA, "it would have done so expressly, as it consistently has in other tariff statutes."

The ruling does not affect sector-specific tariffs Trump imposed separately on steel, aluminium and other goods. Investigations that could lead to additional sectoral tariffs are still ongoing.

The Supreme Court’s decision upholds earlier rulings by lower courts that the tariffs Trump imposed under IEEPA were unlawful. A lower trade court had blocked most of the across-the-board levies in May, but the ruling had been stayed pending the government’s appeal.

AFP