The US Court of International Trade on Wednesday struck down President Donald Trump's tariffs imposed under the 1977 International Emergency Economic Powers Act (IEEPA).
The court ruled IEEPA did not give the president the authority to impose certain tariffs.
This affects the "fentanyl" tariffs imposed by the White House on Canada, Mexico, China since Trump returned to the White House. These tariffs were brought in to curb smuggling of the narcotic into the US.
It also affects the so-called "Liberation Day" tariffs announced on 2 April, including the universal 10% baseline tariff on all imports to the US.
However, the ruling does not affect the Trump administration's 25% "sectoral" tariffs on steel and aluminium imports and also his 25% additional tariffs on cars and car part imports, as these were implemented under a different legal justification.
A US federal appeals court decided on Thursday night that Trump's global tariffs can temporarily stay in place while it considers the White House's appeal against the trade court's judgement - but the future of the President's tariff agenda remains in the balance.