Roberts' opinion, joined by the five other justices, found that the IEEPA's language did not give tariff power to the president. Roberts wrote "Based on two words separated by 16 others in […] IEEPA—'regulate' and 'importation'—the President asserts the independent power to impose tariffs on imports from any country, of any product, at any rate, for any amount of time. Those words cannot bear such weight.[…] IEEPA contains no reference to tariffs or duties.” Moreover, “until now no President has read IEEPA to confer such power." The majority opinion was splintered among the reasons for the opinion's judgement. In one part, joined in opinion by Gorsuch and Barrett, Roberts found the tariffs violated the major questions doctrine. He wrote "When Congress has delegated its tariff powers, it has done so in explicit terms, and subject to strict limits."{{cite news | url = https://www.scotusblog.com/2026/02/supreme-court-strikes-down-tariffs/ | title = Supreme Court strikes down tariffs | first = Amy | last = Howe | date = February 20, 2026 | accessdate= February 20, 2026 | work = [[SCOTUSBlog]] }} In another part, joined by Sotomayor, Kagan, and Jackson, Roberts stated the imposed tariffs were not supported by the language of the IEEPA. Roberts wrote "the president asserts the extraordinary power to unilaterally impose tariffs of unlimited amount, duration and scope", the government "points to no statute" where Congress expressly said IEEPA could apply to tariffs.{{cite news | url = https://www.nbcnews.com/politics/supreme-court/supreme-court-strikes-trumps-tariffs-major-blow-president-rcna244827 | title = Supreme Court strikes down most of Trump's tariffs in a major blow to the president | first = Lawrence | last = Hurley | date = February 20, 2026 | accessdate = February 20, 2026 | work = [[NBC News]] }} Roberts further reasoned that, were "regulate" interpreted to include taxation, that interpretation "would render IEEPA partly unconstitutional", as the law also allows the president to regulate "exportation", where the taxation of exports is unconstitutional per the [[Export Clause]].{{Cite web |date=2026-02-20 |title=Supreme Court Invalidates Executive Tariffs Under IEEPA: A Technical Analysis of Learning Resources, Inc. v. Trump |url=https://www.currentfederaltaxdevelopments.com/blog/2026/2/20/supreme-court-invalidates-executive-tariffs-under-ieepa-a-technical-analysis-of-learning-resources-inc-v-trump |access-date=2026-02-20 |website=Current Federal Tax Developments |language=en-US}}

Roberts' opinion, joined by the five other justices, found that the IEEPA's language did not give tariff power to the president. Roberts wrote "Based on two words separated by 16 others in […] IEEPA—'regulate' and 'importation'—the President asserts the independent power to impose tariffs on imports from any country, of any product, at any rate, for any amount of time. Those words cannot bear such weight.[…] IEEPA contains no reference to tariffs or duties.” Moreover, “until now no President has read IEEPA to confer such power." The majority opinion was splintered among the reasons for the opinion's judgement. In one part, joined in opinion by Gorsuch and Barrett, Roberts found the tariffs violated the major questions doctrine. He wrote "When Congress has delegated its tariff powers, it has done so in explicit terms, and subject to strict limits."{{cite news | url = https://www.scotusblog.com/2026/02/supreme-court-strikes-down-tariffs/ | title = Supreme Court strikes down tariffs | first = Amy | last = Howe | date = February 20, 2026 | accessdate= February 20, 2026 | work = [[SCOTUSBlog]] }} In another part, joined by Sotomayor, Kagan, and Jackson, Roberts stated the imposed tariffs were not supported by the language of the IEEPA. Roberts wrote "the president asserts the extraordinary power to unilaterally impose tariffs of unlimited amount, duration and scope", the government "points to no statute" where Congress expressly said IEEPA could apply to tariffs.{{cite news | url = https://www.nbcnews.com/politics/supreme-court/supreme-court-strikes-trumps-tariffs-major-blow-president-rcna244827 | title = Supreme Court strikes down most of Trump's tariffs in a major blow to the president | first = Lawrence | last = Hurley | date = February 20, 2026 | accessdate = February 20, 2026 | work = [[NBC News]] }} Roberts further reasoned that, were "regulate" interpreted to include taxation, that interpretation "would render IEEPA partly unconstitutional", as the law also allows the president to regulate "exportation", where the taxation of exports is unconstitutional per the [[Export Clause]].{{Cite web |date=2026-02-20 |title=Supreme Court Invalidates Executive Tariffs Under IEEPA: A Technical Analysis of Learning Resources, Inc. v. Trump |url=https://www.currentfederaltaxdevelopments.com/blog/2026/2/20/supreme-court-invalidates-executive-tariffs-under-ieepa-a-technical-analysis-of-learning-resources-inc-v-trump |access-date=2026-02-20 |website=Current Federal Tax Developments |language=en-US}}

Justice [[Neil Gorsuch]] criticized Congress for letting Trump dictate tariffs, rather than legislatively enacting them.{{Cite web|url= https://www.nytimes.com/2026/02/21/us/politics/gorsuch-congress-trump-tariffs.html|title=In Gorsuch’s Homage to Legislative Power, a Subtle Reproach of a Neutered Congress|first1=Catie|last1=Edmondson|access-date=February 21, 2026|date=February 21, 2026}}

Justices [[Clarence Thomas]] and [[Brett Kavanaugh]] wrote separate dissents, with Thomas and [[Samuel Alito]] also joining Kavanaugh's dissent. Kavanaugh wrote that tariffs "are a traditional and common tool to regulate importation" and that because there were numerous other ways that the president could set tariffs by federal statute, those other routes "might justify most (if not all) of the tariffs at issue in this case".

Justices [[Clarence Thomas]] and [[Brett Kavanaugh]] wrote separate dissents, with Thomas and [[Samuel Alito]] also joining Kavanaugh's dissent. Kavanaugh wrote that tariffs "are a traditional and common tool to regulate importation" and that because there were numerous other ways that the president could set tariffs by federal statute, those other routes "might justify most (if not all) of the tariffs at issue in this case".