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.

Oral arguments over President Donald Trump's power to impose tariffs kicked of on Thursday before a U.S. appeals court, after a lower court said he exceeded his authority with sweeping levies on imported goods.

For months President Donald Trump has been slapping higher tariffs on practically every country’s exports to the United States, citing emergency economic powers. Now, just as he’s about to enact a new round of tariffs,