The US Supreme Court decided today, in a 6–3 opinion, that the International Emergency Economic Powers Act (IEEPA) does not authorize the president to impose tariffs.

The IEEPA generally allows a president to take certain economic actions — such as blocking, prohibiting, or restricting transactions involving foreign property — when responding to an “unusual and extraordinary” foreign threat declared a national emergency. Acting pursuant to such declarations, in 2025 the Trump administration imposed a series of tariffs (IEEPA tariffs) on a broad range of imports to address what it identified as two “unusual and extraordinary” threats: the influx of illegal drugs from Canada, Mexico, and China and significant trade imbalances.

Continue reading for our analysis of the decision and the steps importers should consider now to preserve potential refund claims.