US Supreme Court Voids IEEPA Tariffs, Igniting Fresh Trade Turbulence for Container Lines

The US Supreme Court has invalidated the tariffs President Donald Trump imposed under the International Emergency Economic Powers Act, ruling 6-3 that the 1977 law does not authorise the president to levy import duties — a power the Constitution assigns to Congress.

The decision, delivered on 20 February by chief justice John Roberts with justices Sotomayor, Kagan, Gorsuch, Barrett and Jackson, voids the broad “reciprocal” duties announced on Liberation Day in April 2025 and the country-specific levies tied to fentanyl enforcement on imports from China, Canada and Mexico. Tariffs enacted under separate authorities remain in force, including the 50% levy on steel and aluminium under Section 232.

For container shipping, the ruling redraws the near-term tariff landscape but not in the direction many importers had hoped. Within hours of the decision, Trump signed an executive order imposing a 10% global tariff under Section 122 of the Trade Act of 1974, subject to a 150-day time limit without congressional approval. By 21 February he had announced an increase to 15% — the statutory maximum — effective 24 February. The order exempts energy, pharmaceuticals, automobiles, aerospace, critical minerals and USMCA-compliant goods, carve-outs that materially affect which containerised trade flows will see duty changes.