A US federal appeals court has declared that most of the tariffs imposed by former President Donald Trump were illegal and exceeded his authority.

The court rejected Trump’s argument that the tariffs were justified under the International Emergency Economic Powers Act (IEEPA), issuing a 7-4 ruling.

Judges said the IEEPA does not give the president the power to set tariffs, noting that only Congress has that authority. They described the tariffs as “invalid as contrary to law” and emphasized that the 1977 law was not meant to give presidents unlimited control over trade.

The ruling applies to Trump’s “reciprocal” tariffs, which targeted multiple countries worldwide, including China, Mexico, and Canada. Tariffs introduced under other laws, like those on steel and aluminum, are not affected.

The case arose after small businesses and US states challenged the tariffs. Trump’s 2024 executive orders had imposed a baseline 10% tariff on nearly all countries, plus additional reciprocal tariffs.

A lower court had also ruled the tariffs illegal, but the decision was paused pending appeal.

Trump criticized the ruling on Truth Social, calling the court “highly partisan” and claiming that removing the tariffs could “literally destroy the United States.” He argued that the tariffs were vital for economic strength and national security.

Lawyers for the administration warned that overturning the tariffs could cause a financial crisis similar to the 1929 stock market crash, insisting that the levies were important for protecting US security and foreign policy interests.

The ruling is set to take effect on 14 October unless challenged. It is expected to be appealed to the US Supreme Court, which could redefine the limits of presidential authority over trade.

With six Republican-appointed justices, including three by Trump, the case may become a major test of executive power.