A 1977 law that gives the President power to regulate certain economic activity during a declared national emergency. In 2025 it was used to impose the "fentanyl" tariffs on Canada, Mexico and China and the worldwide "reciprocal" tariffs. On February 20, 2026, the Supreme Court ruled in Learning Resources v. Trump that IEEPA does not authorize tariffs. CBP stopped collecting them on February 24, 2026, and began refunding IEEPA duties paid by importers of record in April 2026. The ruling does not affect Section 232 or Section 301 tariffs, which still apply.