In a 6-3 decision, the US Supreme Court held that the International Emergency Economic Powers Act (IEEPA) does not authorize the President to impose tariffs.

The decision says the Constitution’s framers specifically vested the power to lay and collect taxes and duties exclusively with the Legislative Branch (Article I, Section 8). The government conceded that the President possesses no inherent peacetime authority to impose tariffs without Congress.

Chief Justice Roberts’ majority opinion applied the “major questions doctrine,” asserting that a delegation of the core congressional power of the purse requires “clear congressional authorization”. The Court ruled that such a massive delegation of economic and political power cannot be read into ambiguous or vague statutory text. Gorsuch, and Barrett also leaned on that reasoning.

Roberts wrote that the stakes here “dwarf those of other major questions cases,” noting the government’s own claims that the tariffs involved trillions of dollars.

Shares of Nike are a pretty good barometer on how the market sees tariffs holding up.