The U.S. Supreme Court on Friday invalidated President Donald Trump’s broad tariffs on imports from nearly every trading partner. In a 6-3 decision authored by Chief Justice John Roberts, the justices held that Trump overstepped bounds set by the International Emergency Economic Powers Act, or IEEPA, of 1977.

Roberts emphasized the major questions doctrine in his opinion. That principle requires clear congressional authorization for executive actions carrying vast economic and political weight. “The president must ‘point to clear congressional authorization’ to justify his extraordinary assertion of the power to impose tariffs,” Roberts wrote. “He cannot.”

The ruling marks a sharp rebuke to Trump’s trade strategy since he returned to the White House in January 2025. Trump quickly expanded tariffs, citing national security threats from trade imbalances. He targeted goods from China and allies alike, sparking a global trade war. Financial markets tumbled. Ties with partners frayed. Trump defended the levies in a November speech, declaring without them “the rest of the world would laugh at us because they’ve used tariffs against us for years and took advantage of us.”

Business groups and officials from 12 states—most led by Democrats—brought the challenge. They contended the Constitution assigns tariff and tax powers to Congress alone. The tariffs had already generated more than $175 billion in revenue, according to the Penn-Wharton Budget Model. Projections called for trillions more over the next decade. Those funds could now face refund demands.

The court’s conservative majority split on the issue. Justices Neil Gorsuch and Amy Coney Barrett joined Roberts and the three liberals—Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson—in the majority. Justices Clarence Thomas, Samuel Alito and Brett Kavanaugh dissented.

Trump had anticipated a possible defeat. After November oral arguments, he told reporters his team would pursue a “game two” plan if needed. The decision disrupts that approach. Importers may now seek billions in repayments. Global markets reacted swiftly Friday, with U.S. stock futures dipping in after-hours trading.

Congress holds exclusive authority over tariffs under Article I of the Constitution, the challengers argued successfully. IEEPA grants the president emergency powers over foreign transactions during declared crises. But the court found no explicit tariff provision there. Roberts noted the administration’s broad interpretation would cede congressional prerogatives.

Trump’s first term saw similar tariff battles. Courts upheld some under different statutes. This time, with IEEPA at center stage, the high court drew a line. The ruling arrives amid Trump’s renewed push on trade deficits. He blamed countries like China for exploiting U.S. openness.

States including California, New York and Washington led the lawsuit. Business plaintiffs ranged from manufacturers to retailers battered by higher costs. The tariffs hiked prices on steel, electronics, autos and consumer goods. Economists warned of inflation risks and supply chain snarls.

Legal experts called the outcome a win for separation of powers. “This reins in executive overreach on trade,” said Georgetown law professor Jennifer Hillman. Trump administration officials vowed quick study of next steps. Congressional Republicans signaled support for new legislation to back tariffs legally.

The decision hands Congress use in upcoming budget fights. Tariff revenue had padded federal coffers. Without it, deficits loom larger. Trump returns to the campaign trail next week with trade front and center. His allies decry the ruling as judicial interference in America First policy.