Supreme Court struggles with legality of Trump’s tariffs, questions his authority to bypass Congress

President Trump’s fondness for tariffs ran into serious skepticism Wednesday at the Supreme Court, where the justices questioned whether Congress had truly given the executive such an expansive power to slap duties on all foreign goods.

The Constitution grants Congress the power to raise taxes and impose customs duties, but Mr. Trump says a 1977 law has delegated much of that power to the president, and he is using it as leverage in trade negotiations.

Justices on both sides of the aisle questioned his assertion.

“It’s a congressional power, not a presidential power, to tax. You want to say tariffs aren’t taxes, but that’s exactly what they are. They’re generating money from American citizens,” said Justice Sonia Sotomayor, a member of the liberal wing.

Chief Justice John G. Roberts Jr. pointed to another problem with the International Economic Emergency Powers Act that Mr. Trump is using: “The statute doesn’t use the word ‘tariffs,’” he said.

U.S. Solicitor General D. John Sauer said the law uses the term “regulate importation.” He said that has to mean the power to impose tariffs.

“If you had asked the Founders, ‘How do you regulate imports,’ they would say, ‘Of course, we tariff,’” Mr. Sauer said.

Justices are weighing a case brought by small, import-reliant businesses that have challenged Mr. Trump’s global tariffs. The president said the tariffs are intended to produce better terms of trade, with extra levies on Canada, Mexico and China to encourage them to stem the flow of fentanyl to the U.S.

Businesses said the levies on foreign goods were massive burdens that could drive them into bankruptcy.

Mr. Trump has described the case as a matter of “life and death” for the country. He said a loss would disrupt his trade negotiations.

Justices worried about the limits of presidential power and whether Congress meant to, or even could, delegate such an expansive tariff power to the White House.

Justice Neil M. Gorsuch, a Trump appointee, said that under the president’s theory of using emergency power to impose tariffs, a future president could impose a 50% tariff on gas-powered cars and auto parts to combat climate change.

He worried that if the court agreed that Congress had lent this power to the president, it would never be able to regain it. The president would veto any bill to try to reverse the powers.

“It’s a one-way ratchet toward the gradual but continual accretion of power in the executive branch and away from the people’s elected representatives,” he said.

Another Trump appointee, Justice Amy Coney Barrett, seemed taken aback by the breadth of the tariffs.

“I mean, these are kind of across the board,” she said.

Trade is the central plank of Mr. Trump’s second term, alongside immigration enforcement, and the White House is banking on the court’s 6-3 conservative majority to salvage his tariff plans.

Mr. Trump says tariffs, or duties on foreign goods brought to U.S. markets, allow him to generate revenue, gain leverage in international negotiations and protect U.S. industries and workers.

He used the International Economic Emergency Powers Act to impose a blanket tariff of 10% on all imports, as well as nation-by-nation levies that are far higher.

Mr. Trump has compelled Japan and South Korea to invest hundreds of billions of dollars into U.S. projects in exchange for lower tariff rates.

He is using a 50% tariff on Indian imports to stop New Delhi from purchasing Russian oil that funds Moscow’s invasion of Ukraine.

Mr. Sauer said the fentanyl-related tariffs prodded China last week to strike an agreement to try to limit the flow of chemicals used to manufacture the potent synthetic opioid, which claims tens of thousands of American lives each year.

Chief Justice Roberts acknowledged that the tariffs have been “quite effective” as he questioned Neal Katyal, the attorney for businesses that sued to stop some of the tariffs.

Several Republican-appointed justices seemed open to Mr. Trump’s argument.

Justice Brett M. Kavanaugh, a Trump appointee, said President Nixon implemented a global 10% levy in 1971, under an earlier law. He was trying to pressure other nations to resolve a balance-of-payments issue.

Mr. Sauer said that earlier law also spoke of regulating imports and that Congress had the earlier law and Nixon’s actions in mind as it wrote the 1977 law Mr. Trump is using.

“That’s powerful evidence of congressional acquiescence,” he said.

His arguments seemed to have gained support from some of the court’s Republican appointees.

Justices Clarence Thomas and Samuel A. Alito Jr. said there may be room for emergency tariff powers, particularly as a tool of foreign policy.

Justice Thomas postulated a situation in which a president would use tariffs to prod the release of a U.S. citizen being held hostage by a foreign power.

Mr. Katyal said the president could resort to other levers or persuade Congress to approve a tariff in that situation.

Several justices wondered whether Congress had the authority to relinquish its tariff power. One judicial theory, known as the “nondelegation doctrine,” says lawmakers cannot delegate core powers that the Constitution assigns them.

A related “major questions doctrine” holds that Congress must be explicit in granting powers.

Justice Sotomayor said the court cited the major questions doctrine in 2023 in slapping down President Biden’s student loan forgiveness plan.

“So Biden could have declared a national emergency in global warming and then gotten his student forgiveness?” she asked.

Chief Justice Roberts repeatedly returned to the issue. He said tariffs were a “major authority” of Congress and seemed to be a misfit under the International Economic Emergency Powers Act.

The Senate voted last week to terminate Mr. Trump’s tariff authority under the International Economic Emergency Powers Act, including levies on Brazil, Canada and other nations.

That legislation is unlikely to see action in the Republican-controlled House.

Both sides hope the Supreme Court will issue a swift decision in the legal fight, but the justices often take weeks, if not months, to issue opinions in complex cases.

Treasury Secretary Scott Bessent estimates that the U.S. would have to refund $750 billion to $1 trillion in tariff revenue if the court decides against Mr. Trump and the opinion doesn’t arrive until June.

The justices discussed the difficulty of unwinding the tariffs and wondered about the feasibility of issuing refunds.

Mr. Katyal, attempting to offer options to overrule the president, suggested that the justices could provide refunds to the businesses that sued or could make their ruling prospective.

The cases are Learning Resources v. Trump and Trump v. V.O.S. Selections.