Reuven S. Avi-Yonah (Michigan, Google Scholar), Regulatory Taxation And The Tariffs, U. of Mich. L. & Econ. Research Paper (forthcoming 2026):

In Learning Resources Inc. v. Trump , the Supreme Court will decide whether the president has the authority under the International Emergency Economic Powers Act (IEEPA) to impose tariffs. The statute authorizes the president to “by means of instructions, licenses, or otherwise . . . regulate . . . nullify, void, prevent or prohibit, any . . . importation or exportation of . . . any property in which any foreign country or a national thereof has any interest.”  On its face, this seems to grant the president adequate authority to impose a tariff, because a tariff is intended to “regulate” importation, and a power to “prohibit” implies a power to “reduce” by means of the tariff. This paper defends this interpretation of the IEEPA.