Trump’s tariffs are a key plank of his economic policy, which he has said will encourage businesses to invest and produce goods in the US rather than overseas. But the high court’s decision marked a significant check on his power and a major blow to his second-term agenda.

The US president has argued his tariffs are necessary to reduce the trade deficit – the amount by which imports exceed exports – but the US trade deficit reached a fresh high this week, widening by 2.1% compared to 2024 and hitting roughly $1.2 trillion (£890bn).

Drew Greenblatt, owner of Marlin Steel Wire Products, a steel fabrication plant in Baltimore, said he was “very disappointed” by the Supreme Court’s decision.

“It is a setback for poor people in America that had a chance to climb into the middle class with great manufacturing jobs,” he told the BBC.

But John Boyd, a soybean farmer from Virginia and founder of the National Black Farmers Association, said: “This is a huge win for me and a big loss for the president.

“I don’t care how you look at it, President Trump lost on this.”

Yet Allie Renison, a former UK government trade adviser and director at SEC Newgate, said: “While it may seem like a good day for free trade, I think trade actually just got a lot messier.”

She said that businesses are now facing “much more of a patchwork approach” to tariffs under the Trump administration.

It means that US businesses will have to pay a 15% tariff to import most goods into America under Section 122 of the Trade Act of 1974.

But some products will be exempted such as critical minerals, metals and pharmaceuticals.

Meanwhile, separate tariffs on steel, aluminium, lumber and auto-motives – introduced using a different US law – remain in place, untouched by the Supreme Court’s ruling.

On Friday, a White House official said countries that previously reached trade deals with the US, including the UK, would face the global tariff under Section 122 rather than the tariff rate they had previously negotiated.

However, the UK’s deals around steel, aluminium, pharmaceuticals, autos, and aerospace sectors – which represent most of its trade with the US – were not impacted.

The UK government said it expects Britain’s “privileged trading position with the US” to continue and that it is a “matter for the US to determine” whether those deals still stand.

William Bain, head of trade policy at the British Chambers of Commerce, has said he feared that the president’s response to the Supreme Court ruling “could be worse for British businesses”.

The new 15% import tariffs are “bad for trade, bad for US consumers and businesses” and will “weaken global economic growth”, the leader of a UK business group said.

In remarks made before Trump announced the new levy rate of 15%, French President Emmanuel Macron said France will adapt, adding that the “fairest possible rules involve reciprocity, not suffering unilateral decisions”.

Likewise, German Chancellor Friedrich Merz warned of the “poison” of more uncertainty around tariffs.

Merz said he would work closely with other EU countries on a joint position ahead of his upcoming trip to the US.

“The biggest poison for the economies of Europe and the US is this constant uncertainty about tariffs. And this uncertainty must end,” Merz said.