New Delhi, Feb. 21 -- Stocks rallied on Friday after the Supreme Court repudiated the signature pillar of President Donald Trump's trade agenda, but the market's relief is likely to be short-lived. Instead, investors should prepare for a new round of economic uncertainty.

In a 6-3 decision, the court said that Trump broke the law by using the International Emergency Economic Powers Act, or IEEPA, to place tariffs on most of America's trading partners. While IEEPA allows the president to limit trade in many ways, the court said, it didn't give the president tariff powers.

Behind almost every public statement and Truth Social post in which he threatened to bludgeon a trading partner, IEEPA was the power that Trump relied on. Now, that aut...