Trump

Majority — Roberts

Joined by: Sotomayor, Kagan, Gorsuch, Barrett, Jackson

The majority held that the power to impose tariffs is "very clearly a branch of the taxing power," which the Constitution vests exclusively in Congress, and that the President conceded he has no inherent peacetime authority to impose tariffs on his own. The Court reasoned that the word "regulate" — as ordinarily used and as Congress consistently uses it throughout the U.S. Code — means to control, direct, or govern by rule, and does not include the power to tax; the Government could not identify a single other statute in which "regulate" was understood to authorize taxation. The Court further noted that when Congress has delegated tariff authority in the past, it has always done so explicitly — using words like "duty" or "surcharge" — and with strict caps on rates, time limits, and procedural requirements, none of which appear in IEEPA. Three Justices (Chief Justice Roberts, Justice Gorsuch, and Justice Barrett) additionally applied the "major questions doctrine" — a principle requiring clear congressional authorization before courts will read ambiguous statutory language as delegating extraordinary power to the executive — finding that the economic and political stakes here (projected tariff revenues of trillions of dollars, affecting every trading partner) dwarfed those of any prior major questions case. Three other Justices in the majority (Justices Kagan, Sotomayor, and Jackson) agreed IEEPA does not authorize tariffs based solely on ordinary statutory interpretation, without invoking the major questions doctrine, reasoning that the text, structure, and Congress's consistent practice of delegating tariff power with explicit language and tight constraints all point to the same conclusion.

Dissent reasoning

The principal dissent, written by Justice Kavanaugh and joined by Justices Thomas and Alito, argued that the broad power to "regulate . . . importation" plainly encompasses tariffs as a matter of ordinary meaning, history, and precedent — because tariffs are, and have always been, one of the most traditional and common tools used to regulate imports, alongside quotas and embargoes. The dissent pointed to President Nixon's 1971 tariffs, which were imposed under IEEPA's predecessor statute using identical "regulate . . . importation" language and upheld in court, and to the Supreme Court's 1976 Algonquin decision, which unanimously held that a similarly worded statute authorizing the President to "adjust the imports" permitted monetary exactions on foreign oil — meaning Congress enacted IEEPA in 1977 with full awareness that such language covered tariffs. The dissent argued the major questions doctrine does not apply here for two independent reasons: first, because the statutory text, history, and precedent provide the "clear congressional authorization" the doctrine demands, making tariffs under IEEPA anything but an "unheralded" power; and second, because courts have never applied the major questions doctrine in the foreign affairs and foreign trade context, where Congress has historically granted the President broad discretion. Justice Thomas wrote separately to argue that the nondelegation doctrine — which limits Congress's ability to hand its legislative powers to the executive — does not apply to the tariff power at all, because regulating foreign commerce was historically treated as a prerogative (executive-type) power rather than core legislative power, and importing goods is a privilege rather than a right, meaning Congress may freely delegate tariff authority to the President without constitutional constraint.