With tariffs ruling, Supreme Court reasserts its power to check Trump​

After siding with US President Donald Trump in two dozen cases in the past year in ways that boosted his power and let him quickly transform US policies on immigration, military service, federal employment and beyond, the US Supreme Court finally reached its limit.

The court on Friday upended one of Trump's top priorities in his second term as president, deciding in a blockbuster ruling that his imposition of sweeping global tariffs on nearly every US trading partner exceeded his powers under federal law.

The ruling, authored by conservative Chief Justice John Roberts, did not waffle in its scope or effect, or leave questions about the legality of the tariffs to another day. It unswervingly struck them down, making no mention of the consequences for refunds, trade deals or the Republican president himself.

'Legal cover'

In doing so, the court also reasserted its role as a check on the other branches of government, including the president, after a year when numerous critics and legal scholars had increasingly voiced doubts.

"The court has shown it will not necessarily provide legal cover for every plank of Trump's platform," said Peter Shane, an expert in constitutional law and the presidency at New York University School of Law.

The justices in the 6-3 decision upheld a lower court's ruling that Trump's use of a 1977 law called the International Emergency Economic Powers Act - or IEEPA - did not grant him the power he claimed to impose tariffs, something no president had previously tried to do under the statute.

In no uncertain terms, Roberts wrote in the ruling that Trump's argument that a particular phrase in the law's text gave him power to impose tariffs was wrong.

"Our task today is to decide only whether the power to "regulate ... importation," as granted to the president in IEEPA, embraces the power to impose tariffs. It does not," Roberts wrote.

"The decision shows that the Supreme Court is serious about policing the scope of power delegated to the president by Congress," said Jonathan Adler, a professor at William & Mary Law School in Virginia.

"The president cannot just pour new wine out of old bottles," Adler added. "If there are problems current statutes do not address, the president must ask Congress for a newer vintage."

The court has a 6-3 conservative majority, but the ruling was not split along ideological lines. Roberts and fellow conservative justices Neil Gorsuch and Amy Coney Barrett - both appointed by Trump in his first term - joined the court's three liberal members to strike down his tariffs. Three other conservative justices dissented.

Trump pulled no punches in rejoinder, casting the decision in extraordinarily personal terms and reserving special wrath for the Republican appointees including his own who ruled against him, calling them "fools" and "lapdogs" for Democrats.

"They're very unpatriotic and disloyal to our Constitution," Trump told reporters, adding, "It's my opinion that the court has been swayed by foreign interests."

Emergency requests

For most of 2025, the Supreme Court in case after case sided with Trump's emergency requests to lift orders by lower-court judges blocking some of his boldest policies, while litigation challenging them played out.

Those actions on the court's so-called emergency - or "shadow" - docket are usually handled without extensive briefing or oral arguments, in contrast with the court's regular work where cases are assessed over months before a definitive ruling is issued. The tariffs case was argued in November.

Acting in 28 cases on an emergency basis, the court has used multiple legal paths to rule in favour of Trump in 24 of them during his second term, while another was declared moot.

The decisions let him fire federal employees, take control of independent agencies, ban transgender people from the military and deport migrants to countries where they have no ties, among other actions.

Those victories for Trump followed a landmark ruling in 2024 - also authored by Roberts - granting him broad immunity from criminal prosecution on his 2020 election subversion charges.

That decision - and the repeated wins for Trump since - raised doubts among numerous critics and court watchers about the independence of the top US judicial body and its willingness to confront a president aggressively pushing the limits of his power and apt to verbally attack judges who get in his way.

Trump, for instance, called last year for the impeachment of one judge who ruled against him in a major deportation issue, labelling him among other things a "Radical Left Lunatic" - an outburst that prompted a rebuke from Roberts.

At the same time, since early in his second term, questions have swirled over whether Trump's administration has defied unfavourable orders by the federal judiciary, which could provoke a constitutional crisis.

The decisions in favour of Trump frustrated the court's liberals. Justice Ketanji Brown Jackson even observed in one opinion that "this administration always wins."

Still, some experts had urged patience, noting that the court's recent permissiveness toward Trump might change once it resolved the legality of a major policy after extensive deliberation. That happened on Friday.

The shadow docket decisions "were never evidence of the court being particularly sympathetic to or solicitous of the Trump administration," Adler said. "This case, on the other hand, is the first time the court has considered one of the Trump administration's policy initiatives on the merits."

The court is due to hear arguments on 1 April over the legality of another contentious Trump policy, his directive to restrict birthright citizenship in the United States, in another case that could draw pushback from the justices.

Previous losses

During Trump's first term as president, the court handed him some significant losses in pivotal cases, including blocking his plans to add a citizenship question to the national census questionnaire and end a deportation protection for immigrants - known as "Dreamers" - who entered the United States illegally as children.

University of California, Berkeley law professor John Yoo highlighted the fact that the tariffs ruling was joined by justices appointed by both Republican and Democratic presidents.

"The decision belies the attacks from the left that the Supreme Court - particularly its conservative majority - simply rubber-stamps the Trump administration's policies," said Yoo, a former clerk to conservative Justice Clarence Thomas.

Shane noted that the tariffs case did not require the court to wade into the wisdom of Trump's policy or the soundness of his discretion - and may not undermine Trump's power going forward.

"The ruling does suggest that, on pure questions of law that do not put the court in the position of smacking down Trump's motives or second-guessing his judgment, there is a majority that will not rubber-stamp his action," Shane said.