In a significant legal setback for the administration, the Supreme Court ruled 6–3 that the statute used to justify the import duties “does not authorise the President to impose tariffs”, effectively invalidating the unilateral measures imposed on multiple countries.
Soon after, Trump signed a proclamation imposing a 10% ad valorem import duty on articles imported into the United States for a period of 150 days. The temporary duty will take effect February 24 at 12:01 a.m. Eastern Standard Time and will be treated as customs duty.The new tariffs are expected to be introduced under Section 122 of the Trade Act of 1974, which allows the president to impose import surcharges of up to 15% to address balance-of-payments concerns without seeking Congressional approval.
The court, however, did not address whether affected parties would be eligible for tariff refunds, leaving that to be determined by lower courts. Analysts estimate that demands for refunds from affected importers could run as high as $170 billion, more than half the total revenue generated from Trump-era tariffs so far.
US markets reacted positively to the verdict, with the S&P 500 rising 0.69%, the Nasdaq Composite gaining 0.9%, and the Dow Jones adding 230.81 points.

