Hard to believe, but a US court has declared Donald Trump’s global tariffs illegal. What will the White House do now? A tough challenge, but one that needs resolving.

Late last week, a US appeals court ruled that most of Trump's tariffs were unlawful, stating that the president exceeded his authority when imposing them.

The lawsuit was filed by a coalition of 12 Democratic-led states, including Oregon, New York, and California, along with small businesses. They argued that the global tariffs violated the constitutional separation of powers and went beyond the scope of the International Emergency Economic Powers Act (IEEPA).

A panel of judges in Washington upheld the Court of International Trade's decision that the president had misused his emergency powers by imposing the duties. Nevertheless, despite the ruling, the tariffs will remain in place while the case moves through the US legal system.

The decision does not apply to tariffs introduced during Trump's first term. These include duties on steel, aluminum, automobiles, and Chinese goods, which were imposed on different legal grounds.

Notably, in May 2025, the Court of International Trade sided with the plaintiffs, ruling that the tariffs were ultra vires, or beyond legal authority. The Justice Department then appealed the decision and won a temporary reprieve.

Now the White House is also preparing an appeal to the Supreme Court. If the decision on global tariffs is upheld, the tariffs may be eliminated. Experts say this would likely require refunds to importers. The most significant consequence, however, would be setting a precedent of curbing presidential power in trade policy and returning some authority to Congress.