Wall Street is on edge as the U.S. Supreme Court holds a pivotal hearing today (Nov. 5) to determine the legality of President Donald Trump’s wide-ranging tariff policy. The focus is on whether the International Emergency Economic Powers Act (IEEPA) gives the president sweeping authority to impose tariffs without congressional approval or required investigations—a move first used by Trump earlier this year against Canada, China, and Mexico.

A coalition of importers and a dozen states have already won in the federal courts, with judges finding the president lacked authority under IEEPA to levy tariffs. With the case now before the highest court, traders and investors worry a reversal could trigger major volatility across global markets. For importers like Learning Resources, tariff costs soared by a staggering 30-fold in a single year, threatening budgets and business models.

Notably, the White House recently adjusted China-specific tariffs in response to bilateral negotiations, demonstrating tariffs’ critical impact on global trade flows. If the Supreme Court deems the current tariff approach unconstitutional, expect intense risk-off sentiment and rapidly shifting markets as investors scramble for safety.

This landmark case goes beyond U.S.–China relations: it sets a precedent for presidential trade powers and could dramatically reshape Wall Street’s playbook. Stakeholders should stay alert—policy and legal turbulence are converging, and no one is immune.