Trump’s tariff powers, explained: What the US Supreme Court is weighing

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In a pivotal hearing that could reshape the balance of power between the White House and US Congress, the US Supreme Court on Wednesday scrutinised President Donald Trump’s sweeping global tariffs, imposed under a 1977 emergency law. The justices heard nearly three hours of arguments over whether the president overstepped his authority by using emergency powers to levy duties that critics say amount to taxes—a power reserved for Congress under the US Constitution, the New York Times reported.

A sceptical bench

From the outset, several conservative justices expressed unease with the administration’s defence. Justice Amy Coney Barrett questioned why the tariffs, framed as emergency measures, applied to allies like Spain and France. Chief Justice John Roberts noted that while tariffs are tied to foreign affairs, “the vehicle is imposition of taxes on Americans,” a role that has “always been the core power of Congress.” Justice Neil Gorsuch pressed Solicitor General D. John Sauer, who argued for the administration, on whether Congress could “abdicate all responsibility to regulate foreign commerce” and simply hand that authority to the president.

The tax question at the heart of the case

Much of the argument centred on whether tariffs are functionally taxes. Neal Katyal, representing small businesses challenging the policy, argued that “tariffs are taxes” that “take dollars from Americans’ pockets,” and that the founders clearly vested taxing power in Congress. Sauer countered that the tariffs were regulatory tools meant to influence foreign behaviour, not to raise revenue. “They are not revenue-raising tariffs,” he said, insisting their financial impact was incidental. But Justice Gorsuch was unconvinced, remarking that “the power to reach into the pockets of the American people is just different.”

A test of presidential power

The hearing’s undercurrent was the scope of executive authority. Justice Sonia Sotomayor listed the countries targeted by Trump’s tariffs, questioning whether the 1977 International Emergency Economic Powers Act “gives without limit” the ability to impose taxes. Roberts likewise warned that letting presidential powers eclipse Congress’s core authority “neutralizes” the balance between branches. Justice Brett Kavanaugh, however, voiced concern that curbing those powers could undercut the president’s tools for managing global crises, noting tariffs on India tied to the Russia-Ukraine conflict.

Legal alternatives and congressional intent

The justices also examined whether other statutes, like Section 122 of the 1974 Trade Act, could have justified the tariffs instead. Katyal argued those laws include clear limits—15 percent caps and 150-day timeframes—showing that Congress never intended the 1977 emergency law to be used this broadly. Justice Samuel Alito asked whether the Court should consider the president’s authority under other provisions, hinting that the administration’s case may be vulnerable under IEEPA alone.

Reviving an old doctrine

The case also revived talk of the “nondelegation doctrine,” a once-dormant legal theory that restricts Congress’s ability to delegate its powers. Conservative justices, including Alito and Gorsuch, appeared open to reexamining it. When Alito joked that Katyal—who served in the Obama administration—might become “the man who revived” the doctrine, Katyal replied, “Heck yes, Justice Alito,” arguing that allowing such open-ended authority would turn delegation into “legislative abrogation.”

What’s next

A decision is expected before summer but could come sooner given the case’s expedited schedule. If the Court limits Trump’s tariff authority, it could not only upend his trade policy but also set new constitutional boundaries on how presidents use emergency powers. For now, the justices seem poised to decide not just the fate of one trade programme—but how far a president can go in taxing Americans in the name of national security.