Members of the 11-judge panel of the U.S. Court of Appeals for the Federal Circuit in Washington appeared unconvinced by the Trump administration’s insistence that the president could impose tariffs without congressional approval, and it hammered its invocation of the International Emergency Economic Powers Act to do so.

On the day before President Donald Trump's next set of tariff hikes is set to materialize, a federal appeals court will grapple with the big, unanswered question underpinning the president's aggressive and unprecedented trade policies.