WASHINGTON — U.S. President Donald Trump’s key tool for deploying tariffs faces a critical legal test in the Supreme Court — one which could upend his plans to realign global trade.

During Wednesday’s court hearing, the Trump administration’s lawyer faced pushback from Supreme Court justices over whether the national security statute Trump used to hit nearly every nation with devastating duties can be used for tariffs at all.

Trump used the International Emergency Economic Powers Act of 1977, known as IEEPA, for his so-called “Liberation Day” tariffs and fentanyl-related duties on Canada, Mexico and China.

Supreme Court justices questioned the Trump administration’s lawyer Wednesday over the fact that the text of IEEPA does not mention tariffs, and asked him how the president could use

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