The ruling does not stop Trump from trying to impose tariffs under other laws, although these methods come with more limits.
The majority concluded that the Constitution “very clearly” assigns Congress the authority to impose taxes, including tariffs.
Chief Justice John Roberts wrote the majority opinion, and Justices Clarence Thomas, Brett Kavanaugh and Samuel Alito dissented.
“The president asserts the extraordinary power to unilaterally impose tariffs of unlimited amount, duration, and scope. In light of the breadth, history, and constitutional context of that asserted authority, he must identify clear congressional authorization to exercise it,” Roberts wrote. “As such, we hold that IEEPA does not authorize the president to impose tariffs.
“The tariffs at issue here may or may not be wise policy. But as a matter of text, history, and precedent, they are clearly lawful,” Kavanaugh wrote.
In April 2025, Trump imposed what he called “reciprocal” tariffs on most countries and labeled it as “Liberation Day,” citing trade deficits as a national emergency. Earlier duties targeted Canada, China and Mexico, which the administration linked to a declared emergency over drug trafficking.
The measures prompted a wave of lawsuits, including challenges brought by about a dozen predominantly Democratic-led states.
In May 2025, a federal trade court blocked Trump’s efforts to impose broad tariffs under emergency powers, citing violations of U.S. law and the creation of economic turmoil. In August 2025, the tariffs were ruled illegal by a federal appeals court that also referenced IEEPA.
Friday’s decision did not decide or specify whether companies will get refunds for the billions of dollars already paid. Some businesses, including retailer Costco, have asked lower courts to order the government to return the money, The Associated Press reported.
As of December, the Department of the Treasury had collected more than $133 billion from the tariffs imposed under the emergency law, according to federal data.
The economic impact of the tariffs has been projected at roughly $3 trillion over the next decade, according to estimates from the Congressional Budget Office. It is unclear whether the decision will impact tariffs on homebuilding inputs such as lumber, steel, aluminum and copper.
