In the most consequential legal defeat of Donald Trump's second presidency, the US Supreme Court ruled 6-3 on Friday that his sweeping global tariffs were illegal — a landmark judgement with trillion-dollar implications for trade, the economy, and the limits of executive power.
Chief justice John Roberts wrote for the majority, joined by liberal justices Sotomayor, Kagan, and Jackson, along with conservatives Neil Gorsuch and Amy Coney Barrett. Justices Clarence Thomas, Samuel Alito and Brett Kavanaugh dissented.
The Court's core finding was blunt: Trump violated the Constitution's separation of powers when he unilaterally used the International Emergency Economic Powers Act (IEEPA) — a 1977 emergency statute — to impose broad import taxes on virtually every US trading partner.
"The president asserts the extraordinary power to unilaterally impose tariffs of unlimited amount, duration, and scope," Roberts wrote. "In light of the breadth, history, and constitutional context of that asserted authority, he must identify clear congressional authorization to exercise it."
That authorisation, the Court concluded, doesn't exist in IEEPA. The law allows presidents to 'regulate importation' during national emergencies, but it never mentions the words 'tariff' or 'duty.' The majority held that 'regulate' cannot be stretched to include taxing authority — when Congress wants to delegate tariff powers, it uses explicit language, caps rates and sets durations. IEEPA does none of that.
Roberts anchored the ruling in the Constitution itself: "The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises." The executive branch has no inherent peacetime tariff authority. "The United States, after all, is not at war with every nation in the world," he wrote pointedly.
The Court also invoked the major questions doctrine — the same legal principle used to block Biden-era policies on student loan forgiveness and vaccine mandates. When a president claims sweeping authority over a matter of massive economic and political consequence, Congress must have said so clearly. Here, it didn't.
For global markets, the reaction was immediate. The S&P 500 and NASDAQ 100 climbed to session highs following the announcement. US Treasury yields edged up. Investors interpreted the ruling as a reduction in trade policy uncertainty — one of the most persistent drags on business confidence since Trump's 'Liberation Day' announcement nearly a year ago.
What Was Struck Down
The ruling invalidates Mr Trump's most far-reaching tariff actions, specifically those imposed under IEEPA:
- The 'Liberation Day' reciprocal tariffs announced 2 April 2025, which hit virtually all US trading partners with duties as high as 50%
- Tariffs as high as 145% on Chinese imports
- Separate IEEPA-based tariffs on Canada and Mexico, imposed ostensibly over fentanyl trafficking
Crucially, the ruling does not affect sector-specific tariffs imposed under other laws — the 50% duties on steel and aluminum, levies on automobiles and auto parts, and other product-specific measures imposed under Section 232. Those remain in force.
The Money Problem
The financial fallout may dwarf the legal drama. According to US customs and border protection's own published data, the federal government collected US$133.5bn (billion) in IEEPA tariff revenue from over 301,000 importers across 34 million import entries through December 14, 2025. The pace hasn't slowed — the US Treasury's Monthly Treasury Statement recorded US$27.7bn in customs receipts in January 2026 alone. The Penn-Wharton Budget Model at the University of Pennsylvania, cross-referencing Census Bureau import data across 11,000 product categories and 233 countries, puts the total IEEPA haul at US$179bn as of 19 February 2026— all of it now potentially subject to refund. To put that in scale: $179 billion exceeds the combined fiscal 2025 budgets of the department of transportation (US$127.6bn) and the department of justice (US$44.9bn) — and the government collected it in under a year.
The Supreme Court, however, gave no guidance whatsoever on repayments. The majority opinion was silent on whether and how the government must return the money, leaving the question to lower courts. Dissenting justice Kavanaugh, while disagreeing with the majority's legal reasoning, acknowledged the practical crisis ahead: handling refunds would likely be a 'mess'. The administration had already warned during proceedings that mass repayments could have 'devastating consequences' for the US economy.
Importers including Costco had sought injunctions to prevent their payments from being 'liquidated' — finalised in a way that could complicate refunds — but those requests were denied, though courts noted the administration had promised refunds if required.
Global Fallout
The ruling has immediate international dimensions. The EU said it was 'analysing carefully' and remained "in close contact with the US Administration." Brussels emphasised that "businesses on both sides of the Atlantic depend on stability and predictability." The UK expressed confidence that its 'privileged trading position' with Washington would survive, pledging to engage with
US officials on the path forward.
For India, the picture is nuanced. Washington had imposed 25% tariffs on Indian exports under IEEPA in 2025, later doubled to 50% over New Delhi's continued purchase of Russian oil. Those were subsequently reduced to 18% after an interim trade framework was negotiated on 3rd February. The Supreme Court ruling technically invalidates the original IEEPA-based tariffs, but the interim agreement creates a baseline. Indian trade observers see the ruling as strengthening India's negotiating hand heading toward a comprehensive bilateral trade agreement, though Section 232 duties on steel, aluminum, and automobiles continue to apply.
Mr Trump's Response and His Remaining Arsenal
Mr Trump, never one to accept a loss quietly, said he has a 'backup plan.' That's not entirely bluster — the ruling doesn't foreclose tariffs; it only strikes down this particular legal vehicle.
The Constitution delegates taxing power to Congress, but Congress has in turn granted the executive branch several alternative tariff authorities. Each comes with more constraints than IEEPA, but they're real:
Section 232 (Trade Expansion Act of 1962) — Allows the president to impose tariffs for national security reasons, with no cap on rates or duration. But it requires a Commerce Department investigation (up to 270 days) and is designed for specific sectors, not blanket country-wide tariffs. Mr Trump already used this for steel, aluminum, and autos.
Section 301 (Trade Act of 1974) — Allows USTR to impose tariffs against countries engaging in discriminatory trade practices. No rate cap, but requires investigation and consultation with the target country. This is how Mr Trump hit China with hundreds of billions in tariffs during his first term, and Biden expanded them.
Section 201 (Trade Act of 1974) — Permits tariffs if imports are causing serious injury to domestic industries. Capped at 50%, limited to 8 years, and requires an ITC investigation with public hearings.
Section 122 (Trade Act of 1974) — Allows tariffs to address balance-of-payments problems. No investigation required — but rates are capped at 15% and duration at 150 days, after which Congress must approve an extension. Never been used before.
Section 338 (Smoot-Hawley Tariff Act of 1930) — A Depression-era provision allowing tariffs on countries that discriminate against US commerce. Capped at 50%, no investigation required. Also never been used. Legal challenges would be likely if Mr Trump invoked it.
Treasury Secretary Scott Bessent has already signaled the administration will pursue these alternatives to preserve as much of the tariff architecture as possible. The problem: none offer the speed, flexibility, or breadth of IEEPA. Mr Trump's strategy of rapidly raising and lowering tariffs as a negotiating lever — his preferred approach — becomes far harder under laws that require months of investigation before duties can take effect.
The Bigger Picture: A Constitutional Correction
This ruling represents a significant inflection point. For the past year, the Supreme Court's conservative supermajority had largely been handing Mr Trump emergency victories — allowing deportation flights to proceed, greenlighting firings of independent agency heads, and permitting deep spending cuts while legal battles continued. Friday's ruling breaks that streak decisively.
It does so by applying the same logic conservatives used against Biden's executive overreach: agencies and presidents cannot claim transformative powers from ambiguous statutory language, especially on questions of fundamental economic significance. The court in 2023 killed Biden's student loan plan on that basis. The same doctrine now clips Trump's tariff powers.
The Bottom Line
The Supreme Court has drawn a clear constitutional line: the power to tax — including through tariffs — belongs to Congress. Presidents can exercise that power only when Congress has explicitly said so and within the boundaries Congress has set. Emergency law, however broadly worded, is not a blank check to remake global trade policy.
Trump's tariff agenda isn't dead. But it will now have to operate through slower, more constrained legal channels — making the whipsaw tactics that characterised his first year back in office considerably harder to execute. And looming over everything is the refund question: US$179bn in collected duties, a potential legal and administrative crisis that lower courts will have to untangle without guidance from the Supreme Court.
For an administration that bet heavily on tariffs as both economic policy and geopolitical leverage, Friday's ruling is — as Trump himself once predicted — a very terrible blow.
