A court has ruled that Donald Trump’s tariffs are illegal, potentially opening the door for the administration to have to repay billions of dollars in duties.

The US Court of Appeals for the Federal Circuit on Friday evening ruled that it was against the law for Mr Trump to use emergency powers to unilaterally impose import taxes on America’s trading partners.

The 7-4 ruling raises doubts about deals the president has struck with the European Union, Japan, South Korea and other major trading partners to lower the tariff rates from those originally set on April’s Liberation Day.

It also potentially delegitimises tariffs Mr Trump has imposed on China, Canada and Mexico in order to pressure the countries to stop the flow of fentanyl into the United States.

The court said: “The statute bestows significant authority on the President to undertake a number of actions in response to a declared national emergency, but none of these actions explicitly include the power to impose tariffs, duties, or the like, or the power to tax.”