Uncertainty for UK firms after US tariff ruling, experts say

British exporters celebrating Friday's Supreme Court ruling against Donald Trump's emergency tariffs should check their relief at the door. Within hours of the decision, the US president announced plans to reimpose the struck-down levies using 'even stronger' legal authority whilst slapping a new 10% global tariff on all imports. What looked like a judicial reprieve has morphed into something far more dangerous: a protectionist escalation with UK firms caught in the crossfire.

The Supreme Court's decision invalidated tariffs imposed under the International Emergency Economic Powers Act, including the entire suite of 'Liberation Day' levies introduced last April. For UK businesses, that technically eliminates the additional 10% duty Trump had imposed on British goods. Technically.

Trump's immediate response stripped away any illusion of victory. He vowed to reinstate the nullified tariffs through alternative legal mechanisms whilst adding a fresh 10% levy across all trading partners. The message was unambiguous: the legal setback changes nothing, and retaliation is coming.

The Deals That Weren't Worth the Paper

What makes this particularly brutal for British business is the fate of negotiated exemptions. The UK government had secured carve-outs for steel, aluminium, pharmaceuticals, automobiles and aerospace—sectors that account for the bulk of UK-US trade by value. Those deals, painstakingly negotiated, were meant to provide certainty.

A White House official made clear on Friday that countries with existing trade agreements, including the UK, India and the EU, now face the 10% global tariff regardless of their negotiated rates.

The kicker? Those same countries are expected to maintain all the concessions they agreed to under those now-worthless deals. Washington wants one-way compliance: British concessions stand, American promises evaporate.

The British Chamber of Commerce's assessment was diplomatic but pointed. The Supreme Court decision 'does little to clear the murky waters for business', according to head of trade policy William Bain. He noted that Trump retains 'other options at his disposal' to reimpose the invalidated 10% tariff on British goods—a polite way of saying the legal authority exists, and the president has shown every willingness to use it.

The £96bn Refund That Probably Isn't Coming

Then there's the question of money already collected. US customs has pulled in over $130bn (£96.3bn) under the now-invalidated IEEPA tariffs, according to official data. Supreme Court Justice Brett Kavanaugh himself described the likely refund process as a 'mess'—hardly reassuring language from someone intimately familiar with how these administrative tangles unfold.

Trump was even blunter. The refund question, he said, would be 'fought in the courts for the next five years'. Translation: don't hold your breath.

For UK exporters, the refund picture is murkier still. Many of these tariffs were paid by US importers, who then passed costs along the supply chain. Whether British companies that absorbed those expenses indirectly will see a penny back remains anyone's guess. The Chamber of Commerce has raised this precise concern, questioning whether UK exporters will receive any share of potential refunds when American importers were the ones who technically paid.

The financial exposure here is significant. Whilst the UK accounts for a fraction of that $130bn total, British firms have been paying elevated duties for months on goods that courts have now declared were illegally taxed. Recovery mechanisms are unclear, time-consuming, and—if Kavanaugh's assessment is accurate—unlikely to provide swift relief.

False Comfort from Whitehall

The UK government's response has been notably optimistic, perhaps excessively so. A spokesperson insisted the UK 'enjoys the lowest reciprocal tariffs globally' and that 'under any scenario we expect our privileged trading position with the US to continue'.

That confidence seems misplaced given the White House's explicit statement that negotiated rates no longer apply. Trump isn't threatening to reconsider British exemptions—he's already announced he's scrapping them whilst keeping British concessions in place.

The 'privileged trading position' the government references appears to be unraveling in real time, regardless of Whitehall's expectations.

What's striking here is the asymmetry. The sector-specific tariffs the Supreme Court didn't touch—covering steel, aluminium, pharmaceuticals, automobiles and aerospace—remain in force. Those happen to be the exact sectors where the UK had negotiated exemptions. So the court ruling removes tariffs that weren't sector-specific (where Britain had less protection) whilst leaving in place the targeted levies where Britain thought it had secured carve-outs, which are now potentially worthless.

Manufacturing body Make UK captured the mood accurately: British businesses need 'clear, practical guidance on how the ruling will be implemented, alongside progress on resolving the remaining tariffs'. That guidance isn't forthcoming because the administration itself hasn't settled on which legal authority it will invoke to reimpose what it just lost.

The coming weeks will clarify whether Trump can successfully reimpose tariffs through alternative statutory routes. The president claims 'stronger' legal tools are available; trade lawyers will be scrutinising which authorities he invokes and whether courts might strike those down too. Meanwhile, UK exporters face a uniquely uncomfortable position: unable to collect on a court victory, stripped of negotiated protections, and waiting to see which legal mechanism delivers the next round of levies. Court wins mean little when the other side controls the rulebook and has already announced they're rewriting it.