Donald Trump is the first president to use the International Emergency Economic Powers Act to impose tariffs, teeing up likely legal battles that will test his executive authority.

Trump has long proposed raising tariffs—or taxes on imported goods that the businesses importing them pay the U.S. government—before the election, and said in November he’ll impose a 25% tariff rate on all imports from Mexico and Canada on the first day of his presidency and will impose an additional 10% tariff rate on all imports from China on top of other tariffs.

Prices could rise for certain goods — including gas, cars and groceries — and the economy could tip into recession.