On February 20, the Supreme Court handed down a fragmented ruling against most of the tariffs President Trump has imposed since the beginning of his second term. In a show of deep disagreement, the nine Justices produced seven opinions, emphasizing the wide range of different philosophies on the current Court. Justice Roberts primarily wrote for the majority, holding that the President’s power to “regulate … imports” under the International Emergency Economic Powers Act does not include tariffs. This opinion also included all three Democratic-appointed justices, as well as Justices Neil Gorsuch and Amy Coney Barrett. Justice Kavanaugh wrote in support of the Trump Administration’s position that the tariffs were lawful, joined by the Court’s staunch conservatives, Justices Clarence Thomas and Samuel Alito. Justice Elena Kagan spoke for the Court’s liberals, supporting the outcome but reiterating a longstanding opposition to the Major Questions Doctrine, which her conservative colleagues in the majority invoked here.  

Justice Roberts’s opinion relies on the assumption that tariffs should be considered a form of taxation. That is, the money collected incidental to encouraging domestic production and reducing outsourcing is not constitutionally different from all other forms of taxes, like income taxes and sales taxes. Taking this view almost certainly determines the outcome of the case against President Trump. Taxation is a core congressional power, and the scores of regulatory agencies in Washington that wield control over business cannot levy new taxes against them. Justice Kavanaugh’s dissenting opinion views tariffs in a fundamentally different way. He accepts the government’s view that they are designed to change behavior, protect national security, and encourage American manufacturing, rather than raise money for the government. Given this, they should be viewed as a form of regulation, well within the long tradition of Presidential involvement in trade policy. This definitional dispute proved to be decisive in the breakdown of the case, with ultimately more Justices landing on the tariffs-as-taxes position and treating them accordingly.  

Besides the questions directly related to tariffs, the extended debates in the opinions about the Major Questions Doctrine were notable. The Major Questions Doctrine refers to the requirement that when government actors claim a statute gives them the power to do something, they must show that there actually is clear and specific authorization in that law for that action. This concept rose to prominence after the opinion in FDA v. Brown & Williamson Tobacco Corp., 529 U.S. 120 (2000), where Justice Sandra Day O’Connor wrote for the majority. In that case, they held that the FDA needed specific authorization in the law to regulate tobacco, which, until a few years after that case, they did not have. Since 2000, the Major Questions Doctrine has inspired numerous rulings striking down agency actions that were beyond their legal authority, and Landmark has written in support of several. Within the concurrences in this case, there was a show of disagreement on how to apply MQD. Justice Gorsuch criticized Justice Barrett in his concurrence for past statements claiming that MQD is a formalization of commonsense statutory interpretation principles. He instead reasoned that the canon is in fact a departure from past practice and should be regarded as such.  

But regardless of how individual Justices understand the doctrine, the cases where it gets applied usually have similar contours. They typically feature conservative Justices being the most willing to overturn executive action not plainly authorized by Congress, and the liberal Justices much more lenient with how they read delegations of power. The discord here, with the liberals now taking a strict stand on implied grants of power with a Republican in the White House, did not go unnoticed by court watchers or the Justices themselves. Justice Gorsuch wrote in his opinion that the liberals’ use of MQD philosophy in this case, even without naming it, was hypocritical. He criticized them directly and cited their unwillingness to strike down three major executive actions along similar lines during the Biden Administration: student loan forgiveness, COVID-19 vaccine mandates, and power plant regulations. Justice Kagan responded to this accusation by reiterating her opposition to MQD as a tool for judges but declined to further explain her reasoning in any past cases.  

Two other solo opinions illuminated a few other tangential philosophical points that failed to gain traction with other justices. Justice Thomas wrote a solo dissent in which he explained why he thinks the tariffs satisfy nondelegation doctrine scrutiny, namely that nondelegation only applies to delegated “power[s] to make substantive rules setting the conditions for deprivations of life, liberty, or property.” He says this refers only to rules of private conduct, rather than interactions with the government like duties and tariffs. This is an uncommonly narrow view of the nondelegation doctrine for a conservative Justice. Justice Jackson’s solo concurrence was very brief and argued for a consideration of the legislative history in this case, which she claimed counseled strongly against permitting the tariffs to stay in place. Investigating legislative intent has fallen out of favor with most of the Justices because it can be an imprecise way of figuring out how a law should function, especially when you can simply examine the law itself. Justice Jackson has signaled her desire to return to the practice anyway.  

Ultimately, the practical implications of this decision are likely to be mixed and take at least months to sort out. For starters, if the IEEPA tariffs were unconstitutional all along, businesses and American consumer groups both could plausibly seek some sort of refunds. But figuring out who would be eligible, and how much they could receive, is likely to be a very long and contentious process. Second, there are several other statutes that President Trump has previously used to impose tariffs that he could invoke again. Justice Kavanaugh mentioned three in his dissent, and said that because those options remain, “the decision might not substantially constrain a President’s ability to order tariffs going forward.” Nevertheless, these other statutes have restrictions like time limits and agency action in them that will restrict the President’s ability to recreate the IEEPA tariffs entirely. President Trump has already indicated that he intends to use these statutes to replace IEEPA tariffs in the upcoming months, so Justice Kavanaugh’s prediction that the immediate effects of the majority opinion on markets and price levels may be modest may come true.  

This case is the latest in a long series of recent decisions where the Supreme Court invalidates executive action because they did not find sufficient statutory authorization. See National Federation of Independent Business v. OSHA, 595 U. S. 109 (2022) (vaccine mandates); West Virginia v. EPA, 597 U. S. 697 (2022) (power plant regulations); FDA v. Brown & Williamson Tobacco Corp., 529 U. S. 120 (2000) (tobacco regulations); and Biden v. Nebraska, 600 U. S. 477 (2023) (student loan forgiveness). These cases reflect dissatisfaction with the increasing congressional dysfunction and inability to legislate. As the pace of formal lawmaking sputters, the Court has made clear it will not condone a redefinition of the role of the Executive Branch to take on Congress’s functions. Given this, it is likely that the Major Questions Doctrine will remain key to deciding many of the high-profile cases that the Court decides in the years to come.