The US Supreme Court issued this decision on 20/2, according to the WSJ. The White House has not yet commented on the ruling.

During arguments regarding the case, judges expressed skepticism about the legality of the tariffs Trump imposed, Reuters reported. They cited the International Emergency Economic Powers Act (IEEPA), a 1977 law designed for use in national emergency situations.

Previously, the Trump administration appealed lower court rulings, arguing that the president had exceeded his authority.

Trump cited the IEEPA to impose what he termed "reciprocal" tariffs on imported goods from almost all US foreign trade partners, aiming to reduce trade deficits.

He also utilized the same act to impose tariffs on Trung Quoc, Canada, and Mexico, asserting that the smuggling of fentanyl and other illegal drugs into the US constituted a national emergency.

Chief Justice John Roberts authored the 20/2 ruling. Roberts referenced a previous Supreme Court decision, stating that "the President must demonstrate clear authorization from Congress" to justify asserting the power to impose tariffs—a special and unusual authority. The Chief Justice emphasized that in this case, "Trump failed to do so."

According to Roberts, if Congress intended IEEPA to grant the President the specific and special power to impose tariffs, they would have explicitly stipulated it, as they consistently do in other tariff laws.

The Chief Justice of the US Supreme Court also clarified that Congress holds the power to enact and collect taxes, tariffs, duties, and excises. Roberts affirmed that the Trump administration's arguments, claiming an emergency to create a loophole in the Constitution's principle of separation of powers, failed to convince the court.

"Therefore, the government must concede that the President has no inherent authority to impose tariffs in peacetime. After all, the United States is not at war with every nation in the world," Roberts wrote in the ruling.