US trade court blocks Trump's sweeping tariffs

A US federal court has blocked President Donald Trump's sweeping tariffs, in a major blow to a key component of his economic policies.

The Court of International Trade ruled that an emergency law invoked by the White House does not give the president unilateral authority to impose tariffs on nearly every country.

The Manhattan-based court said the US Constitution gives Congress exclusive powers to regulate commerce with other nations and this is not superseded by the president's remit to safeguard the economy.

The court also blocked a separate set of levies the Trump administration imposed on China, Mexico and Canada since returning to the White House, in response to what it said was the unacceptable flow of drugs and illegal immigrants into the US.

The attorney general of New York, one of 12 states involved in the lawsuit, welcomed the decision.

"The law is clear: no president has the power to single-handedly raise taxes whenever they like," Letitia James said.