A federal appeals court panel grilled the Justice Department attorney and challengers over the legality of President Trump's tariffs.

The U.S. Constitution gives the power to impose taxes — including tariffs — to Congress. But lawmakers have gradually relinquished power over trade policy to the White House. And Trump has made the most of the power vacuum, raising the average U.S. tariff to more than 18%, highest since 1934, according to the Budget Lab at Yale University.

The Trump administration’s tariffs are facing a major challenge in front of federal judges. Meanwhile, Mexico got a 90-day reprieve from higher rates.