The US Supreme Court has ruled that the White House overstepped its authority in imposing sweeping tariffs under a law reserved for national emergencies, handing a significant legal setback to the administration’s trade agenda. Experts have responded to the ruling, outlining its potential implications across markets and the US economy.
Analysts suggest that while the ruling curtails broad tariff powers, financial markets are likely to respond pragmatically, factoring in both opportunities and uncertainties in equities, bonds, and the US dollar.
Nigel Green, CEO of global financial advisory giant deVere Group, comments:
“This ruling strikes at the core of the administration’s economic doctrine. Trade confrontation was positioned as the engine of renewed domestic strength. Instead, it now faces constitutional limits, market scrutiny, and diminishing economic returns.”
He continues: “Tariffs were sold as a lever to rebalance trade and protect US industry. In practice, they have functioned as a tax on importers, many of whom passed costs directly to consumers. Corporate margins have tightened in sectors reliant on global supply chains, and investment decisions have been delayed amid policy uncertainty.”
Recent economic data underscore the fragility of the current environment. Growth has moderated from last year’s pace, while inflation measures have shown renewed firmness in categories exposed to higher import costs. Wage growth remains solid, yet household purchasing power is constrained by elevated prices in services and goods.
Green explains: “The economy’s not collapsing, but it’s losing velocity. Inflation remains persistent enough to limit policy flexibility, and business confidence is sensitive to abrupt regulatory and trade shifts. Today’s Supreme Court decision injects a new variable into that equation.”
Despite the political blow, he argues that markets are unlikely to respond with sustained panic.
“Investors differentiate between political theatre and earnings power. Equity markets are forward-looking, and they are being supported by strong balance sheets in major US corporations, continued capital expenditure in AI and tech, and expectations that policymakers will ultimately avoid extreme outcomes.”
He adds: “Large-cap equities, particularly in AI infrastructure, semiconductors, and cloud computing, continue to attract global capital. Even if tariff authority is curtailed, the structural investment cycle in advanced computing and automation remains intact.”
Bond markets, however, may react with greater nuance.
“If tariffs are rolled back or diluted, some inflationary pressure tied to import costs could ease over time, which may support the longer end of the Treasury curve. Yet persistent fiscal deficits and firm wage growth can also be expected to keep upward pressure on yields.”
Currency markets face competing forces.
“The US dollar could experience bouts of volatility. Reduced trade tension may support global risk appetite, tempering safe-haven flows into the dollar.”
He cautions against simplistic conclusions. “A judicial setback does not automatically reverse the economic trajectory. Implementation timelines, potential legislative responses, and geopolitical reactions all matter. Markets will price in probabilities.”
Corporate America, he observes, is likely to adapt quickly.
“Many multinationals have already diversified supply chains and restructured sourcing strategies in anticipation of prolonged trade friction. A recalibration of tariff authority may ease cost pressures incrementally, but strategic shifts made over the past year will not be undone overnight.”
Nigel Green concludes: “President Trump’s tariff-driven strategy is under clear strain following this ruling. The legal boundary has been reinforced, and the economic case for broad-based trade barriers has weakened. Yet financial markets are pragmatic. If the result is greater clarity, reduced policy unpredictability, and sustained investment in AI and tech, equities can advance even as the political narrative fractures. Investors should expect volatility around policy announcements and court developments, firmer scrutiny of fiscal sustainability, and selective strength in sectors with durable earnings growth.”
Stuart Kousoulou, Quantitative Trader, CMC Markets, said:
“The Supreme Court’s ruling striking down Trump’s tariffs has so far been positive for risk assets, particularly equities and global markets, by reducing a major policy uncertainty.
It also clarifies legal boundaries on trade policy, which helps long-term investment planning. However, lingering questions remain about refunds and the practical limits, small business impacts, alternative tariff authorities, along with Trump’s and the White House reply and next move.”
George Lagarias, Chief Economist at Forvis Mazars comments:
“Back to the races, but not square one. The Supreme Court’s decision, while not wholly unexpected, throws the US government’s aggressive geoeconomic strategy in disarray. The ruling casts a shadow on the US budget, as full refunds could add more than half a percentage point to the deficit. Having said that, we have long maintained that this will simply prompt the US government to shift gears, from country tariffs to product tariffs, where the President has considerably more leeway to impose without Congressional approval.
Nevertheless, the ruling may well embolden US trade partners, as the White House will find it more difficult to threaten wide tariffs in cases of non-compliance.
It’s probably good news for consumers and importer companies (who stand to benefit from possible refunds) and bad news for American long-term debt, as more bond issuance could be required to cover possible budget shortfalls.”
Lizzy Galbraith, Senior Political Economist at Aberdeen Investments, said:
“The Supreme Court has announced a full strike down of tariffs levied under the International Emergency Economic Powers Act.
IEEPA tariffs account for almost seven percentage points of the 11% implemented US weighted average tariff rate. So, the immediate impact would be for tariffs to decline substantially.
But the Trump administration will likely seek to rebuild the tariff wall to a roughly similar, though likely lower, level through an expansion of the use of Section 232 and 301 tariffs. Use of section 122 is also possible. This may well lead to a period of heightened uncertainty as policy adjusts.
“However, these measures have more constraints than IEEPA as used by President Trump. Section 232 and 301 measures are principally sectoral in nature and require trade investigations before their application. While legally durable, these tariffs could not be applied with the speed that has been typical of President Trump’s tariff policy to date.
It is possible the administration will seek to use Section 122 to quickly rebuild the tariff wall. Section 122 allows the President to levy tariffs of up to 15% to address balance of payments issues. Broad use of section 122 may well lead to further legal action, and given the 15% cap on tariffs applied under this law, it again offers less flexibility than IEEPA. Long-term use of tariffs under this measure also requires Congressional authorisation, which seems less likely given recent votes against President Trump’s tariffs on Canada.
Other questions remain. Tariffs had become a meaningful source of revenue for the US government, and the loss of IEEPA will not only affect future revenue-generating potential but raises questions of whether these funds need to be repaid. Crucially, the court ruling did not address this issue, so legal action will continue. This will act as a source of uncertainty for affected businesses and for the US fiscal outlook.
Nonetheless, despite political and practical constraints, President Trump still views tariffs as a useful tool with which to gain leverage on trade and non-trade issues. Though the loss of IEEPA leaves tariff policy meaningfully more constrained, a policy pivot away from tariffs is unlikely.”
John Wyn Evans, Head of Market Analysis, at Rathbones, one of the UK’s leading wealth and asset management groups, says:
“The US Supreme Court caught markets on the hop by ruling 6-3 in favour of declaring President Trump’s IEEPA tariffs illegal. The full implications are as yet unclear, not least because any decision about refunding tariffs already collected (around $175bn) has been deferred to a lower court.
Any decision-making process on this could be messy and drawn out. Unsurprisingly, reaction has been as you would expect along party lines with the President labelling the decision as a “disgrace”.
The ruling is something of a double-edged sword. On the positive side, it removes some of the burden from companies and consumers, as well as alleviating inflation concerns. It also helps exporters to the US. That has been reflected in firmer equity markets. On the other hand, the reduction in potential government income in the face of higher spending promises points to higher fiscal deficits, a risk reflected in an underperformance of Treasury bonds vs global peers.
However, this is by far from being the end of the tariff story. There are other ways for President Trump to impose tariffs. Various others can be imposed to address national security concerns (section 232, already in use), to remedy unfair trade practices (301, also being used) or to penalise countries that discriminate against US commerce (338). Section 122 allows universal tariffs of up to 15% for 150 days to address balance-of-payments deficits. We should be prepared for all sorts of interesting definitions of these factors. The Yale Budget Lab’s immediate assessment was that the rate of tariffs in force will fall from 16.9% to 9.1%.
Another positive factor is the fact that SCOTUS delivered this ruling. It is not in hock to the White House, as many feared. Therefore, the constitutional checks and balances that protect the country are not in complete disrepair. Indeed, we have seen more vocal opposition to Trump’s policies from within his own party recently. However, the lack of pushback from corporate USA remains a concern.”
US GDP
The headline US Q4 GDP print initially surprised, with annualised growth slowing to 1.4% from 4.4% in Q3. That said, quarter‑to‑quarter volatility is often exaggerated by annualisation. Recent GDP data have been distorted by several temporary factors, including volatile inventories of pharmaceuticals and precious metals linked to tariffs, and the government shutdown, which shaved an estimated 0.9 percentage points off growth. Some of this drag should reverse in Q1, alongside additional fiscal support from last year’s One Big Beautiful Bill Act.
More concerning is that inflation remains sticky. Core PCE rose from 2.8% to 3%, potentially tempering rate‑cut expectations. As the Fed’s preferred inflation gauge, Core PCE is less influenced by shelter costs than CPI and therefore remains relatively elevated despite slowing rental growth.
While stronger nominal GDP growth is not necessarily negative for equities – particularly for firms with pricing power – slower rate cuts and higher bond yields remain a headwind to activity and valuations. This does not yet amount to evidence of stagflation, but lower inflation without a sharp growth slowdown would be preferable. The outlook for 2026 remains broadly constructive, with improving soft data, although the “no hire, no fire” labour market could still weaken, despite better‑than‑expected initial jobless claims.”
