Supreme Court’s Tariffs Ruling Answers Some Major Questions, Leaves Others Open

The Supreme Court today issued its long-awaited decision in Learning Resources, Inc. v. Trump, holding — by a 6–3 vote — that the International Emergency Economic Powers Act (IEEPA) does not authorize the President to impose tariffs during peacetime. The central question in the case was whether IEEPA’s authority to “regulate … importation” authorized the President to impose broad tariffs to address drug trafficking and trade deficits. Chief Justice Roberts’s majority opinion said no, with six Justices agreeing that the text of IEEPA does not permit tariffs. But even within the six-Justice majority, the Justices fractured sharply over the role of the major questions doctrine in reaching that result.

Major Questions Background

The major questions doctrine, crystallized in cases like West Virginia v. EPA and Biden v. Nebraska, instructs courts to require “clear congressional authorization” when an agency or the Executive asserts regulatory power of vast economic and political significance. The doctrine reflects a structural concern: Congress does not typically hide transformative delegations in broad or ambiguous language. When the asserted power is novel, economically sweeping, or touches a core constitutional prerogative, courts demand more than general text.

In defending the President’s tariffs, the government sought to sidestep the doctrine in two principal ways. First, it argued that IEEPA’s emergency context distinguished it from prior major questions cases. Because the statute was designed to give the President flexibility to respond to crises, the government contended that Congress intentionally used capacious language to confer broad discretion. Second, the government urged that foreign affairs and trade warrant special deference. Tariffs, it argued, are classic tools of economic statecraft, and Congress has historically afforded the President substantial latitude in this domain.

The Court’s Opinions

The Chief Justice, joined by Justices Gorsuch and Barrett in relevant part, treated the case as a classic major questions dispute. The President had claimed sweeping authority — tariffs of potentially unlimited scope and duration — based on general language authorizing him to “regulate” imports. That, the plurality reasoned, is not enough when the asserted power implicates Congress’s core Article I authority over taxation and carries vast economic and political consequences.

The plurality emphasized that the doctrine applies with heightened force where the Executive claims authority touching “core congressional power[s].” In the Chief Justice’s words: “These considerations apply with particular force where, as here, the purported delegation involves the core congressional power of the purse.” Against that backdrop, the majority concluded that Congress's general language authorizing regulation of imports could not be read to silently delegate the taxing power.

The plurality also pushed back sharply on the government’s assertion — echoed in Justice Kavanaugh’s dissent — that IEEPA, as a statute designed to deal with “the most major of major questions,” should be reviewed more deferentially. The Chief responded bluntly: “There is no major questions exception to the major questions doctrine.” Emergency statutes and foreign-affairs settings, the plurality held, do not dilute the requirement of clear congressional authorization.

Justice Gorsuch wrote separately to defend the major questions doctrine as a structural safeguard rooted in separation of powers, characterizing it as a necessary protection against executive aggrandizement. Justice Barrett agreed with the result but took a narrower view of the doctrine’s foundation, describing it as a context-sensitive application of ordinary textualism rather than a free-standing clear-statement rule. On the other side, Justice Kagan, joined by Justices Sotomayor and Jackson — though voting to strike down the tariffs as unauthorized — rejected reliance on the major questions doctrine altogether. In their view, traditional tools of statutory interpretation sufficed: “regulate … importation” does not naturally include the power to tax, and Congress, through other statutes, has demonstrated that it knows how to delegate tariff authority explicitly when it chooses to do so.

Justice Kavanaugh, joined by Justices Thomas and Alito, dissented. He argued that history and precedent show tariffs are a longstanding means of regulating imports and that IEEPA’s text clearly covers them. In his view, the majority improperly extended the major questions doctrine into the foreign-affairs realm.

Major Questions Implications

Although the major-questions portion of the Chief Justice’s opinion garnered only two additional votes, its reasoning offers potential hooks for future challenges to federal action.

Taxing and revenue-adjacent authorities are especially vulnerable. The plurality’s emphasis on Congress’s exclusive power over “the purse” suggests that agency or executive actions with revenue-raising features — even if styled as regulatory — may trigger heightened scrutiny. Where an agency imposes fees, penalties, or financial exactions under general “regulate” language, litigants should consider framing the case as implicating core Article I powers.

No emergency carveout. The Chief Justice’s opinion squarely rejected the idea that emergency statutes dilute the major questions doctrine. That holding is portable. When agencies rely on crisis-based delegations — public health, national security, financial stability — litigators can argue that urgency does not relax the requirement of clear statutory authorization.

Foreign affairs is not a safe harbor. Though the plurality recognized that circumstances could differ in wartime, it declined to create a foreign-affairs exception to the major questions doctrine. And it applied the doctrine with full force to action taken directly by the President — not merely by a federal agency. Those moves undercut arguments that presidential decisions in the international arena are categorically different for purposes of major-questions analysis. For sanctions, trade controls, export restrictions, and similar tools of economic statecraft, challengers can now argue that even general grants of authority in the foreign-affairs sphere remain subject to major questions’ scrutiny.

Historical nonuse matters. The plurality leaned heavily on the absence of prior presidential reliance on IEEPA for tariffs. That reinforces a litigation strategy of building a record showing that the asserted authority is novel or unprecedented — particularly where an agency suddenly discovers broad new power in decades-old statutory text.

A $170 billion question remains unanswered. Today’s decision does not address how the estimated $170 billion in IEEPA tariffs collected to date will be handled. We expect further guidance from U.S. Customs and Border Protection, along with further proceedings in the lower courts addressing potential refunds of duties paid.

Arnold & Porter is closely monitoring developments in litigation over the Trump administration’s tariffs and, more generally, the major questions doctrine. If you have questions, please reach out to one of the authors of this post or your regular Arnold & Porter contact.

© Arnold & Porter Kaye Scholer LLP 2026 All Rights Reserved. This Blog post is intended to be a general summary of the law and does not constitute legal advice. You should consult with counsel to determine applicable legal requirements in a specific fact situation.