President Donald Trump on Saturday announced an increase in the global tariff rate on imports into the United States to 15 per cent, escalating his trade policy just a day after the Supreme Court of the United States struck down much of his earlier tariff program.

Posting on his Truth Social platform, Trump described the court’s decision as “extraordinarily anti-American” and said his administration would raise import levies “to the fully allowed, and legally tested, 15% level” following a review of the ruling.

On Friday, the Supreme Court delivered a 6–3 judgment rejecting Trump’s authority to impose sweeping tariffs under a 1977 economic emergency powers law. In response, he initially unveiled a new 10 per cent global levy using a separate legal pathway before increasing it further to 15 per cent.

The Republican president also launched a sharp criticism of conservative justices who sided with the majority, accusing them of “disloyalty” and calling them “fools and lap dogs.”

The ruling marked one of Trump’s most significant setbacks at the high court since returning to office 13 months ago, despite the court having generally ruled in his favour in previous cases.

Saturday’s move is expected to inject fresh uncertainty into global markets, as Trump continues a trade strategy that has seen tariff levels imposed, revised, or withdrawn over the past year as part of broader negotiations with both allies and rivals.

Under US law, the newly announced duty is temporary and can remain in effect for up to 150 days. A White House fact sheet noted exemptions for sectors under separate investigations, including pharmaceuticals, as well as goods covered by the United States-Mexico-Canada Agreement.

The administration said trading partners that negotiated separate tariff agreements with Washington would also be subject to the new global rate.

High court defeat

The Supreme Court’s decision did not affect sector-specific tariffs previously imposed on steel, aluminium and other goods, nor did it halt ongoing government investigations that could lead to additional duties.

Trump praised the three conservative justices who dissented — Clarence Thomas, Samuel Alito and Brett Kavanaugh — thanking them for what he described as their “strength and wisdom.”

He alleged that the six-justice majority, including two appointees from his first term, had been influenced by foreign interests, though he did not provide evidence.

Wall Street shares rose modestly on Friday following the court’s decision, which many analysts had anticipated. Business groups welcomed the ruling, with the National Retail Federation saying it offered “much-needed certainty” for companies.

During court arguments, the administration indicated that companies would be refunded if tariffs were ultimately ruled unlawful, though the Supreme Court did not directly address that issue in its decision. Trump predicted prolonged litigation over potential refunds, while Justice Kavanaugh acknowledged the process could become complicated.

International reactions were swift. German Chancellor Friedrich Merz said he would consult European allies to develop a coordinated response before travelling to Washington in early March.

At home, Pennsylvania Governor Josh Shapiro urged the president to respect the court’s ruling and end what he described as “chaotic tariffs,” warning of the impact on farmers, small businesses and families.