The Constitution grants Congress the power to “lay and collect Taxes, Duties, Imposts and Excises” and to “regulate Commerce with foreign Nations.” Tariffs are a tax, and the Framers of the Constitution expressly contemplated the exclusive grant of taxing power to the legislative branch; when Patrick Henry expressed concern that the President “may easily become king,” James Madison replied that this would not occur because “[t]he purse is in the hands of the representatives of the people.”

Federal appeals court strikes down major chunk of Trump’s tariffs (Politico)