After IEEPA: Section 301 as the New Core of U.S. Tariff Policy and Its Implications for Korea

On February 20, 2026, the U.S. Supreme Court held, by a 6-3 majority, that the International Emergency Economic Powers Act (“IEEPA”) does not authorize the President to impose tariffs. The ruling invalidated the legal basis for the Trump Administration’s IEEPA-based tariff measures, including the so-called “trafficking tariffs” imposed on imports from Canada, Mexico, and China, as well as the broader “reciprocal tariffs” imposed on imports from almost all U.S. trading partners. The decision, however, should not be understood as a general judicial repudiation of presidential tariff authority. Its holding was confined to IEEPA and did not directly address tariffs imposed under other trade statutes, including Section 122 of the Trade Act of 1974, Section 301 of the Trade Act of 1974, and Section 232 of the Trade Expansion Act of 1962. Accordingly, the central question after the IEEPA decision is not whether U.S. tariff policy will recede, but how it will be reconstructed under alternative statutory authorities. In this respect, Section 301 is emerging as one of the principal legal vehicles for the next phase of U.S. tariff policy. Unlike the IEEPA, Section 301 authorizes the U.S. Trade Representative (“USTR”) to take action, including the imposition of duties or other import restrictions, when the statutory requirements are satisfied. These requirements may be met where a foreign act, policy, or practice is unjustifiable and burdens or restricts U.S. commerce, or where it is unreasonable or discriminatory and burdens or restricts U.S. commerce. This shift became visible shortly after the Supreme Court ruling. On March 11 and 12, 2026, USTR initiated two major Section 301 proceedings: one concerning structural excess capacity and production in manufacturing sectors of 16 economies, and another concerning the alleged failure of 60 economies to impose and effectively enforce prohibitions on the importation of goods produced with forced labor. Korea is included in both investigations.