This article was published in the New York Times on June 4, 2025.
(The New York Times)—Are President Trump’s “Liberation Day” tariffs on, or are they off? And, more important, will legal challenges to these levies put the brakes on the seizure by presidents of both parties of ever-increasing unilateral power?
Two federal courts recently ruled that Mr. Trump lacks authority to impose them, but a specialized federal court with authority over tariff cases, the Court of Appeals for the Federal Circuit, paused the enforcement of those decisions, ordering lawyers to submit legal briefs before a hearing on Monday. One or both cases are likely to land at the Supreme Court in short order.
Understandably, most of the commentary has focused on the practical ramifications for the president’s trade negotiations and the American economy. But the cases may be even more important for the future of a fundamental component of the Constitution’s architecture: the separation of powers, intended by the founders to prevent any of the government’s three branches from becoming all powerful.
The tariff litigation is shaping up as the biggest separation-of-powers controversy since the steel seizure case in 1952. There, President Harry Truman assumed control over the nation’s steel mills to ensure the continued supply of armaments needed for the Korean War. The Supreme Court rebuffed Truman, establishing the principle that, even in an emergency, the president cannot take upon himself powers that are granted neither by the Constitution nor by congressional statute. The case has been cited in court decisions repeatedly since then and is central to most law school courses on constitutional law.
It is clear that the president has no inherent constitutional authority to set or change tariffs or any other taxes. That authority is expressly given to Congress in the first clause of Article I, Section 8, of the Constitution. And it is also clear that Congress has not expressly delegated any power to the president to impose tariffs on his own say-so.
The question is whether vague language in a 50-year-old statute, the International Emergency Economic Powers Act of 1977, gives the president the tariff-setting power. That act delegates various powers to the president “to deal with any unusual and extraordinary threat” to U.S. national security, foreign policy or economy. The statute makes no mention of tariffs or other taxes, and before Mr. Trump, no president ever interpreted it to include such a power.
But the statute does empower the president to regulate the import of “any property in which any foreign country or a national thereof has any interest by any person.” This is the language the Trump administration points to in support of his “Liberation Day” tariffs.
Is that right?
The answer to this question will reverberate far beyond the issue of tariffs, because the federal statute books abound with vaguely worded laws that, if broadly interpreted, could empower Mr. Trump and future presidents to take upon themselves extensive powers never intentionally delegated by Congress. If the courts uphold the Trump tariffs, it will be a major step toward a presidency that does whatever the president wishes to do.
As presidents of both parties have grown increasingly aggressive about asserting unilateral power rather than attempting to work with Congresses often dominated by the other political party, the Supreme Court has faced other variants on this issue — but never one as stark and consequential as the tariff case.
During the Biden administration, the court invalidated a significant number of executive actions on the ground that they lacked adequate statutory authorization. In doing so, the conservative majority relied on two major jurisprudential doctrines.
First is the nondelegation doctrine, which holds that it is unconstitutional for Congress to delegate some legislative power to the executive branch without providing an “intelligible principle” to guide and limit executive discretion. In practice, the court always steps back from actually holding statutes unconstitutional under this doctrine, but it motivates the justices to refuse to interpret statutes in such a way as to amount to a grant of unbridled discretion.
Second, the court employs what has come to be known as the major questions doctrine. This is a canon of statutory interpretation that requires the executive branch to “point to ‘clear congressional authorization’” to justify exercises of “highly consequential power beyond what Congress could reasonably be understood to have granted.” The doctrine kicks in when executive action has immense “economic and political significance,” based on such indications as the breadth of the claimed authority, the history and novelty of the action, the congressional response and other contextual clues about congressional intent. The common sense behind this doctrine is that Congress is unlikely to give the executive branch vast powers without making that intention explicit.
The courts in both tariff cases invoked these principles. As the U.S. Court of International Trade, which has jurisdiction over tariffs and other issues of international trade, stated, both the nondelegation and the major questions doctrines “indicate that an unlimited delegation of tariff authority would constitute an improper abdication of legislative power to another branch of government.” The judges on this panel were appointed by Presidents Ronald Reagan, Barack Obama and Trump and thus cannot be dismissed as motivated by partisanship.
Judge Rudolph Contreras of the U.S. District Court for the District of Columbia emphasized in his decision blocking the bulk of Mr. Trump’s tariffs that the term “to regulate” does not naturally include a power to tax. Although taxation can serve the purpose of regulation, agencies given the power to regulate an activity are not typically understood to be able to use that power to raise revenue through taxation. After all, the Constitution itself distinguishes between the two powers, providing for them in two separate clauses of Article I, Section 8, outlining the enumerated powers of Congress.
The Court of International Trade emphasized the relation between various trade statutes. In 1971, President Richard Nixon used the same language — “to regulate importation,” which appeared in the 1917 Trading With the Enemy Act — to justify the imposition of a temporary surcharge on all imports. Congress acted to make sure this did not happen again. It limited the Trading With the Enemy Act to wartime and enacted the landmark Trade Act of 1974, which detailed specific measures for handling trade deficits and limited those measures’ size and duration. The international trade court held that these limits, rather than the more general language of the International Emergency Economic Powers Act that Mr. Trump has invoked as his authority, governs the imposition of tariffs like Mr. Trump’s.
Both courts reasoned that it is implausible to think that Congress would pass specific statutes granting tariff authority subject to strict limits and then pass a broad statute, not even mentioning tariffs, that allows the president to impose tariffs of any amount on goods from any country for indefinite periods for any reason he deems to be an emergency.
These are the very types of arguments courts recently used to strike down Biden administration initiatives such as student loan forgiveness, the Covid-era eviction moratorium, mandatory vaccination and expansive interpretation of the Clean Air Act to cover climate change regulations. Even if the Republican-appointed justices were inclined to favor Mr. Trump (which I do not think they are), it would be difficult for them to explain why the arguments that were fatal to the Biden administration’s overreach do not apply here.
Even if a court disagreed and construed the International Emergency Economic Powers Act language as allowing tariffs in an emergency, a court can interpret “unusual and extraordinary” in a common-sense way as a situation where there is an urgent necessity for action, with no time to seek authority from Congress.
Urgent necessity is the intelligible principle that defines an emergency. If Mr. Trump wants Congress to give him blanket authority to impose tariffs to combat “large and persistent trade deficits,” which by his own account happened over generations, he should ask Congress to expressly grant him such broad authority.
Any other interpretation would allow the president to ignore the limiting terms of the statute if he finds it inconvenient. That would not be the constitutional republic the founders designed.
Michael W. McConnell directs the Constitutional Law Center at Stanford, where he is a professor. He was appointed by President George W. Bush to the U.S. Court of Appeals for the 10th Circuit, where he served from 2002 to 2009.
A correction was made on June 5, 2025: An earlier version of this article misstated the name of a 1977 law. It is the International Emergency Economic Powers Act, not the International Economic Emergency Powers Act.