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 really given the executive such an expansive power to slap duties on all foreign goods.

The Constitution gives the power to raise taxes and impose customs duties to Capitol Hill, but Mr. Trump says lawmakers, in a 1977 law, delegated much of that power to him, and he’s using it as leverage in trade negotiations.

Justices on both sides of the aisle questioned that.

“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,” Justice Sonia Sotomayor, a member of the liberal wing, said.

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.

But U.S. Solicitor General D. John Sauer said the law does use the term “regulate importation,” and 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, which the president said are intended to prod better terms of trade, and extra levies on Canada, Mexico and China to get them to stem the flow of fentanyl to the U.S.

Businesses said the levies on foreign goods were a massive burden and could drive them into bankruptcy.

Mr. Trump has called the case a matter of “life and death” for the country, saying a loss would send his trade negotiations into disarray.

Justices, though, worried about the limits of presidential power and whether Congress meant to — or even could — delegate so expansive a tariff power to the White House.

Justice Neil M. Gorsuch, a Trump appointee, said 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 with Mr. Trump that Congress lent this power to the president, Congress would never be able to get it back. Any bill to try to undo the powers would be vetoed by the president.

“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 IEEPA to impose a blanket tariff of 10% on all imports and nation-by-nation levies that are far higher.

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

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

And Mr. Sauer said the fentanyl-related tariffs just prodded China last week to strike an agreement to change its policies to try to limit the flow of chemicals used to manufacture the potent synthetic opioid that 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 lawyer for businesses that sued to stop some of the tariffs.

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

Justice Brett M. Kavanaugh, a Trump appointee, said President Nixon used 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 Congress had it, 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 backers with some of the court’s GOP appointees.

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

He postulated a situation where 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 get Congress to approve a tariff in that situation.

Several justices wondered if Congress had the authority to give away its tariff power. One judicial theory, known as the “nondelegation doctrine,” says lawmakers cannot lend out core powers the Constitution assigns them.

There’s also the related “major questions doctrine,” which holds that if Congress does grant its powers, it must be explicit in doing so.

Justice Sotomayor said the court slapped down President Biden’s student loan forgiveness plan in a 2023 ruling citing the major questions doctrine.

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

Chief Justice Roberts also returned to the issue repeatedly, saying tariffs were a “major authority” and horseshoeing them in under IEEPA “seems to be a misfit.”

The Senate voted last week to terminate Mr. Trump’s tariff authority under IEEPA, including levies on Brazil, Canada and other nations.

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

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

Treasury Secretary Scott Bessent estimates 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 on Wednesday touched on the difficulty of unwinding the tariffs, wondering about the feasibility of refunds.

Mr. Katyal, trying to give them other options to overrule the president, suggested they could just give 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.