WASHINGTON, D.C.: U.S. President Donald Trump's ability to unilaterally impose far-reaching tariffs has given rise to skepticism among a majority of the Supreme Court judges.

This could well be the most significant legal test of Trump's presidency yet.

Three conservative justices have questioned the emergency law that gives Trump nearly limitless power to set and change import duties, with potentially trillion-dollar implications for the global economy.

The court's three liberal justices also appeared uncertain, so at least two conservative votes could limit Trump's tariff power under the law. It likely would not end it altogether, however.

The case is the first significant item on Trump's agenda to come before the nation's highest court, which he helped shape by naming three of the nine justices in his first term. The conservative majority has so far been reluctant to check his extraordinary flexing of executive power through short-term orders, ranging from high-profile firings to significant cuts in federal funding. That could change with a more detailed ruling in the tariff case, though it may be weeks or months before a verdict is handed down.

The Constitution says Congress has the power to levy tariffs. However, the Trump administration has argued that an emergency law allows the president to regulate imports, including imposing tariffs.

Justice Neil Gorsuch believed that it could shift too much congressional power to the president on an issue that helped spark the American Revolution.

"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, and added, "power to reach into the pockets of the American people" must be "done locally, through our elected representatives."

Chief Justice John Roberts raised questions about whether the emergency-power law allowed for tariffs on "any product, from any country, in any amount, for any length of time."

Justice Amy Coney Barrett also pressed the government on the broad range of Trump's actions. "Spain? France? I mean, I could see it with some countries, but explain to me why so many countries needed to be subject to the reciprocal tariff policy."

Regulating Commerce or Raising Money?

Solicitor General D. John Sauer said lopsided trade deals are a "global problem," and Trump's tariffs are primarily about regulating foreign commerce to be fairer, rather than raising money that would encroach on Congress's taxation power. "The fact that they raise revenue is only incidental," he said.

Within hours, though, Trump said his tariffs would help slash the deficit. He called the case one of the most important in the country's history and said a ruling against him would be catastrophic for the economy.

The case focused on two rounds of tariffs. The first was imposed in February on imports from Canada, China, and Mexico after Trump declared a national emergency over drug trafficking. The second was a broader set of "reciprocal" tariffs on most countries announced in April.

At the Supreme Court, much of the debate centered on the "major questions doctrine," a legal principle that has already blocked significant policies of former President Joe Biden, including his $500 billion student loan forgiveness plan.

Those challenging the tariffs argued they should be struck down under the same doctrine, since they would have a much larger economic impact, raising about $3 trillion over the next 10 years.

The government countered that the tariffs are different because they are part of Trump's foreign policy, an area where courts should not second-guess the president.

Some justices appeared to agree. Justice Brett Kavanaugh said limiting the president's ability to respond to an emergency by removing key tools seemed unusual. Chief Justice John Roberts also expressed concern about restricting presidential powers in foreign affairs too much.

The challengers argued, however, that the tariffs function like a domestic tax because Americans essentially pay the cost.

Attorney Neal Katyal, representing small businesses opposing the tariffs, warned that if the court sided with Trump, Congress would permanently lose control over tariff policy. He said no future president would agree to give that power back.

If Trump ultimately loses the case, the consequences could be complex, especially if the government is required to refund money already collected. So far, the Treasury has taken in nearly $90 billion from tariffs imposed under emergency powers.

Even so, tariffs are unlikely to disappear. Trump could still impose them under other laws, though those laws place stricter limits on how quickly and how aggressively he could act.