Our New Amicus Brief in the Section 301 Tariff Case

The Cato Institute, Stanford law Prof. Michael McConnell and I recently filed an amicus brief before the US Court of International Trade, in litigation challenging Donald Trump’s massive Section 301 tariffs. Michael McConnell is one of the nation’s leading experts on executive power, a prominent conservative originalist constitutional law scholar, and was our lead counsel in the Supreme Court phase of the case that led to the invalidation of Trump’s IEEPA tariffs.

Here’s a summary of our brief, which I prepared for the Cato website (which will also post the brief soon):

In February 2026, the Supreme Court invalidated the massive tariffs that President Trump attempted to impose under the International Emergency Economic Powers Act (IEEPA). But that decision did not end Trump’s efforts to unilaterally impose onerous tariffs. He has sought to recreate sweeping tariffs using other statutes. Most recently, he has sought to impose massive 10-12.5% tariffs on imports from sixty US trading partners, using Section 301 of the Tariff Act of 1974. The new tariffs were enacted under the pretext of combatting goods produced by “forced labor.” Two groups of small businesses and 25 state governments, led by the state of Oregon, have filed lawsuits in the US Court of International Trade challenging the legality of the Section 301 tariffs.

Cato, Professor Michael McConnell, and Professor Ilya Somin, our B. Kenneth Simon Chair in Constitutional Studies, have filed an amicus brief opposing the new Section 301 tariffs. McConnell is a law professor at Stanford University, a former federal appellate judge, and served as lead counsel for the victorious plaintiffs in the  Supreme Court phase of the IEEPA tariff case.   Somin previously served as co-counsel in the same case. We thank Daniel Wolff, Alexander Schaefer, and Joshua Claybourn of Crowell & Moring for assistance in drafting and filing the brief.

Part I of our brief explains that Section 301 grants limited authority to impose tariffs in response to specific “unreasonable or discriminatory” government policies by “a foreign country” that “burden[] or restrict[] United States commerce.” It is not a blank check for whatever tariffs the executive branch may want to impose against dozens of countries around the world.

Part II outlines why, if there is any ambiguity about whether Section 301 authorizes these massive tariffs, the major questions doctrine requires that the issue be resolved against Defendants. That doctrine obliges Congress to “speak clearly” when it assigns to the executive “decisions of vast ‘economic and political significance.'” The impact of these massive Section 301 tariffs is as large or larger than most policies previously invalidated by the Supreme Court on major questions grounds. And the tariff power is not exempt from major questions scrutiny on the supposed ground that it is a “foreign affairs” power.

Part III shows that if Section 301 did grant the President the power he claims, it would violate the nondelegation doctrine, which constrains transfer of legislative power to the executive. If Defendants’ interpretation of Section 301 is correct, the Office of the United States Trade Representative (USTR) can impose unlimited tariffs on virtually any imports from any country at any time. Such a sweeping delegation of a core congressional power would violate the requirements that (1) Congress not make “boundless” delegations of the power to tax, and (2) that “[t]he ‘guidance’ needed is greater when an agency action will ‘affect the entire national economy’ than when it addresses a narrow, technical issue.”

The full brief is available here.

I previously wrote about the Section 301 tariffs and why they are illegal in this Dispatch article. Cato and I also recently submitted an amicus brief in the related Section 122 tariff case, which is currently before the US Court of Appeals for the Federal Circuit.