Shortly after taking office, President Trump issued a series of executive orders imposing new duties on imports from dozens of countries, resulting in rapid increases and (partial) decreases in tariff rates—from 10 to 145 percent. The President claims the tariffs are necessary to combat illegal drug trafficking and trade imbalances, both of which he has declared “national emergencies.” Therefore, he relied on the International Emergency Economic Powers Act of 1977 (IEEPA) to impose tariffs on nearly every U.S. trading partner.

IEEPA gives the President broad powers to block transactions between Americans and foreign citizens when responding to an “unusual and extraordinary threat.” And for decades, Presidents have used this law to impose economic sanctions on nations or individuals. But this is the first time a President has imposed tariffs under IEEPA.

The new tariffs have imposed large costs on many owners of American businesses. Learning Resources, Inc. and hand2mind, Inc.—family-owned businesses that import and sell educational toys for children—sued the President in the U.S. District Court for the District of Columbia to block the tariffs. They argued that setting duties exceeded the President’s legal authority under IEEPA and violated the Constitution.

The district court agreed with Learning Resources and hand2mind, and it preliminarily enjoined the tariffs. Now, the administration has appealed to the U.S. Court of Appeals for the D.C. Circuit. Cato has filed an amicus brief in support of Learning Resources and hand2mind.

In our brief, we provide historical context about Congress’s constitutional role in tariff policy and IEEPA’s original purpose. Under the recent Supreme Court precedent Loper Bright v. Raimondo (2024), courts must independently determine the best reading of a statute and not defer to the executive’s interpretation. We highlight several problems with the administration’s position that show it is not the best reading of IEEPA.

First, Article I, Section 8 of the Constitution vests the power to impose tariffs solely in Congress. For more than a century, Congress set tariff rates directly—even in times of war and national crisis. The reason for this longstanding practice is clear: Congress cannot vest duty-setting power—a legislative power—with the President, just as Congress cannot vest judicial power with the President or the Speaker of the House.

Second, IEEPA’s text provides no support for the President’s tariff authority. When Congress has delegated some tariff authority to the President, it has done so clearly and explicitly, as in the Trade Expansion Act of 1962 and the Trade Act of 1974. IEEPA is different. It makes no mention of “tariffs” or “duties,” and no President has used it to impose tariffs in the nearly 50 years since it became law—until now.

Finally, the government’s position runs contrary to IEEPA’s purpose. Congress passed IEEPA to limit executive power during emergencies. Even President Franklin Roosevelt—who had an expansive theory of presidential power and was President during economic depression and a global war—never used IEEPA’s more powerful predecessor, the Trading with the Enemy Act, to modify tariffs.

It is thus ironic—and legally untenable—for a President to invoke IEEPA for tariff-setting authority that no President has ever exercised. The Court should reject the government’s position, affirm the district court’s decision, and block the imposition of these tariffs.