In recent years, the U.S. Supreme Court has shown that it will not let the executive branch act on big economic and political questions unless Congress clearly allows it. This approach is known as the “substantial issues doctrine” (sometimes called the “major questions doctrine”). Under this rule, federal agencies—or even the president—cannot make decisions with large economic or political impact unless Congress has spoken directly.
Trump’s Use of Emergency Powers
President Trump used the International Emergency Economic Powers Act (IEEPA) of 1977 as the legal basis for many of his global tariffs. IEEPA lets the president regulate trade during a declared national emergency. Trump invoked IEEPA twice:
February 1 Executive Order: Tariffs on China, Mexico, and Canada, tied to a declared emergency over illegal immigration and drugs.
April 2 “Liberation Day” Order: Reciprocal tariffs on several countries around the world.
IEEPA was originally passed to limit presidential powers under the older Trading with the Enemy Act (TWEA), which dated back to World War I. TWEA gave the president broad control over economic transactions during wartime or emergencies. IEEPA replaced this power for most modern crises, but it was never used before to impose tariffs.
Legal Challenges and Lower Court Rulings
Legal teams have challenged Trump’s tariffs on the grounds that IEEPA does not clearly let the president set trade policy. The key question is whether these tariffs involve issues of “substantial economic and political significance.” If they do, critics say Congress must have given explicit approval.
U.S. Court of International Trade (CIT) in New York City: Last week, this court overturned many of Trump’s tariffs. The CIT found that the president did not have clear authority under IEEPA to impose these trade measures.
U.S. Court of Appeals for the Federal Circuit in Washington, D.C.: On Thursday, this court allowed Trump’s tariffs to remain in place temporarily. It will review the case until the legal arguments finish.
If the case reaches the Supreme Court, it could follow earlier decisions that limited executive power. For example:
2022 EPA Case: The Supreme Court, by a 6-3 vote, said the Environmental Protection Agency needed clear congressional authority to regulate greenhouse gas emissions.
2023 Student Loan Forgiveness Case: The Court ruled that President Biden needed explicit permission from Congress to forgive billions in student debt under the HEROES Act.
These rulings show the Court’s readiness to block major executive actions if Congress has not clearly approved them.
Government’s Defense: National Security Exception
The administration argues that the “substantial issues doctrine” does not apply to national security matters. They claim that when the president cites a national emergency—such as threats from foreign countries—he has wide latitude under IEEPA. According to this view, the doctrine limits federal agencies but not the president’s powers in matters of national security.
Expert Opinion: Doctrine Applies Despite Emergency Claims
Aaron Tang, a constitutional law professor at the University of California, Davis, believes the tariffs clearly involve major questions and must meet the doctrine’s test. He notes that IEEPA has never been used to impose tariffs before. If the doctrine still means anything, it should apply no matter who is president.
Tang says that to uphold Trump’s tariffs, courts will need to explain why the doctrine does not apply or why it should be set aside because of urgent economic risks.
He argues that Trump’s tariffs have “greater economic significance than any policy of the Biden administration” and thus fall squarely under the doctrine.
Tang acknowledges it is possible, though unlikely, that courts could find a way around the doctrine in this case. But he stresses that challengers have strong arguments that Congress never clearly authorized these trade actions.
Potential Supreme Court Impact
If the Federal Circuit’s decision is appealed to the Supreme Court, the justices will face a familiar choice: either uphold executive power in setting broad trade policy under IEEPA or reinforce limits on the president’s authority without explicit congressional approval.
If the Court finds the tariffs involve a major question, it could strike them down.
If the Court accepts the national security exception, the tariffs could remain in place.
Either outcome will shape how future presidents can use IEEPA or other emergency powers to affect trade on a large scale.
