Where does tariff authority come from? The Constitution gives Congress the power to lay duties on imports; since the 1930s Congress has delegated conditional slices of that power to the president through specific statutes: Section 232 of the Trade Expansion Act of 1962 (tariffs when the Commerce Department finds imports threaten national security), Section 301 of the Trade Act of 1974 (responses to other countries' unfair trade practices, on a USTR investigation), Section 201 (temporary safeguard tariffs after a U.S. International Trade Commission injury finding), and — until the Supreme Court held in V.O.S. Selections (February 20, 2026) that the International Emergency Economic Powers Act of 1977 does not authorize tariffs at all, striking down the «reciprocal» tariff program and remapping the administration's remaining options onto the investigation-based lanes.
How each process runs
- Section 232: Commerce investigates (with the Defense Department's input), reports to the president within roughly 270 days; the president has 90 days to act, and actions may last indefinitely — steel and aluminum tariffs under this authority have run since 2018.
- Section 301: USTR investigates foreign practices, allowing public comment, then chooses remedies — tariffs, negotiated settlements, or both; the China-tariff rounds of 2018–2019 ran on this track.
- Section 201: the ITC finds serious injury; the president decides remedy — the 2018 washing-machine safeguard was this route's most recent headline use.
- IEEPA: no investigation or time limits — the president declares a national emergency under the National Emergencies Act and acts; speed is its appeal and litigation its price.
What Congress kept for itself
Everything else: tariff schedules legislatively set, and the constitutional floor that delegation cannot hand over an unguided taxing power. Two live constraints police the line. First, the major-questions style of statutory reading — post-West Virginia v. EPA (2022) — under which sweeping economic action needs clear congressional authorization, the reasoning that carried the day in the 2026 tariff decision. Second, the nondelegation doctrine itself, revived at the margins by some justices' separate writings. Trade-law watchers should read the emerging opinions as a remapping: each ruling narrows or confirms a lane.
How do tariffs end?
Four ways: presidential revocation; statutory expiration (201 safeguards sunset after four years absent extension); negotiated settlement (Section 301 tariffs traded for commitments); or congressional override — which the trade statutes provide only in specific procedures like the Section 232 disapproval resolution, unused in practice. Court invalidation is the newest exit, and the February 2026 IEEPA ruling made it real: importers now press refund claims for duties paid under the invalidated authority while the administration re-imposes tariffs through the surviving 232 and 301 lanes.
What businesses should track
The Federal Register notices announcing each investigation, product list, and exclusion process — exclusion requests under 232 and 301 are their own administrative practice, decided product by product. Court dockets in the trade cases, since vacatur can unwind duties prospectively while refunds hinge on scope. And each statute's calendar: comment periods in 301 cases are where importers put their data into the record that later litigation and negotiations both use.
FAQ
Can the president set tariffs alone?
Only within delegated lanes — 232 national-security findings, 301 unfair-practice responses, 201 safeguards — 232 and 301 remain; the IEEPA lane was closed by the Court in February 2026.
What is the IEEPA case about?
The Court answered it February 20, 2026, in V.O.S. Selections: IEEPA does not authorize tariffs, invalidating the «reciprocal» duties.
Do tariffs expire?
Safeguards do (four years); 232 and 301 actions can run indefinitely absent settlement or revocation.
For more context, read How Congress Kills a Federal Rule in 60 Days.
For more context, read executive order.
For more context, read section 1115 waiver.