In rolling out the most aggressive tariff regime in the US in nearly a century, President Donald Trump has leaned heavily on emergency powers that had never been used before to impose import taxes.

The president is set to raise taxes on imports arriving from many countries, including India. That’s on top of the tariffs that the White House has already announced on scores of products.

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.