Within hours of the ruling, Trump said he would pursue tariffs under alternative statutory authorities. In a Feb. 20 proclamation posted by the White House, he imposed a temporary 10% ad valorem import surcharge under Section 122 of the Trade Act of 1974 for 150 days, effective Feb. 24 at 12:01 a.m. EST.

A White House fact sheet said the temporary duty exempts certain categories of goods, including USMCA-compliant products from Canada and Mexico, as well as items already subject to Section 232 national security tariffs. As a result, existing Section 232 steel and aluminum measures remain unchanged, while some North American materials flows avoid the additional surcharge.

Over the weekend, Trump also said he wanted to raise the global rate to 15%, the statutory maximum allowed under Section 122, according to reports from The Associated Press and Reuters.

A 15% rate would represent the highest temporary surcharge permitted under Section 122 and would increase cost exposure on non-exempt imported materials relative to the 10% level outlined in Friday’s proclamation, though the White House has not issued a revised order reflecting that higher rate.

Writing for the Court in the Feb. 20 decision, Chief Justice John Roberts said IEEPA does not grant the President authority to impose tariffs. “Fulfilling that role, we hold that IEEPA does not authorize the President to impose tariffs."

Roberts emphasized that “[t]he power to impose tariffs is ‘very clear[ly] . . . a branch of the taxing power,’” which the U.S. Constitution assigns to Congress.

The Court rejected the administration’s reading of IEEPA as permitting tariffs under its authority to “regulate” importation. It warned that such an interpretation would allow the President to impose tariffs “of unlimited amount and duration, on any product from any country,” so long as a national emergency is declared.

The ruling dismantles a central component of the administration’s 2025 trade regime. According to the Budget Lab at Yale, approximately $142 billion was collected in 2025 under IEEPA authority.

The Court affirmed the judgment of the U.S. Court of Appeals for the Federal Circuit and vacated the D.C. District Court’s ruling, remanding the case with instructions to dismiss for lack of jurisdiction.

The Majority: Congress Controls the Tariff Power

Roberts’ opinion rests on a constitutional premise: Congress, not the President, controls the power to levy duties unless it clearly delegates that authority.

The Constitution gives Congress authority to “lay and collect Taxes, Duties, Imposts and Excises.” The opinion underscores that tariff authority falls within that taxing power.

When Congress intends to authorize the President to impose duties or tariffs, the Court noted, it does so expressly. IEEPA contains no reference to “tariffs” or “duties.”

In a separate opinion for the majority, Justice Elena Kagan wrote that “The President has the ability to regulate, but not to impose taxes on, imports,” explaining that Congress distinguishes between regulatory authority and revenue-raising authority.

The Court grounded its decision in statutory interpretation rather than the “major questions” doctrine — a principle requiring clear congressional authorization before the executive branch exercises powers of vast economic and political significance. Although the tariffs carried sweeping economic consequences, the majority did not rely on that doctrine, focusing instead on IEEPA’s text and structure.

The opinion declined to create a foreign-affairs exception to ordinary statutory interpretation principles, concluding that Congress does not cede core fiscal powers through broad or ambiguous language.

The Dissent: Emergency Authority and Import Regulation

Justice Brett Kavanaugh, writing in dissent, argued that IEEPA’s authorization for the President to “regulate . . . importation” during national emergencies includes the power to impose tariffs.

In his view, the majority adopted an unduly narrow reading of the statute and failed to account for the breadth of authority Congress intended to confer in emergency settings.

Kavanaugh also addressed the major questions doctrine directly. While that doctrine requires clear congressional authorization before the executive branch exercises powers of vast economic and political significance, he wrote that it should not apply in the foreign-affairs context, noting that six justices would not apply it in that setting.

He argued that ordinary statutory interpretation, not a heightened clear-statement rule, should govern emergency trade authority.

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Refunds, Reliquidation and the Court of International Trade

Although the Court invalidated the IEEPA tariffs, it did not specify how refunds of tariffs already paid must be administered.

Under U.S. trade law, disputes over duties assessed by Customs and Border Protection fall within the jurisdiction of the U.S. Court of International Trade. Whether importers recover duties paid in 2025 may depend on procedural posture and how the trade court structures relief.

The temporary Section 122 surcharge is separate from the invalidated IEEPA duties and does not retroactively alter entries already assessed under that law.

A key concept is liquidation. When Customs and Border Protection finalizes duties on an entry, that entry is liquidated. Importers then have a limited window to file a protest. If no timely protest is filed, the assessment becomes final.

International trade attorneys at Squire Patton Boggs warned that “once liquidation occurs, an importer generally cannot obtain a refund of duties,” underscoring the importance of preserving rights while litigation remains pending.

The Budget Lab at Yale said the Court did not rule out allowing importers to claim refunds, and it is likely a substantial portion of revenue raised under IEEPA in 2025 will be returned to affected parties, though the process remains uncertain.

Contractors, however, should not assume there will be retroactive cost relief. “We have been cautioning our members for some time now that it is unlikely they will see any refunds for materials purchased during the past year,” Brian Turmail, AGC vice president of marketing, communications, fundraising and market insights, told ENR in an email.

For contractors and suppliers, that uncertainty means tariff costs embedded in 2025 bids may stand even if refunds are ultimately issued.

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What Authorities Remain

The ruling narrows one statutory pathway but does not eliminate presidential tariff authority.

Trump said following the decision that his administration would rely on remaining statutory tools. The Section 122 surcharge serves as a temporary bridge while the administration evaluates longer-term trade actions.

In a Feb. 20 client alert, law firm Thompson Hine wrote that the decision “invalidates the President’s reliance on IEEPA as authority to impose tariffs,” but stressed that it “does not disturb tariffs imposed under other statutory authorities, including Section 232 of the Trade Expansion Act of 1962 and Section 301 of the Trade Act of 1974.”

The firm added that those statutes “contain distinct investigative and procedural frameworks that were not at issue in this litigation.”

Law firm Holland & Knight similarly emphasized the separation between IEEPA and other trade tools, writing that “Section 232 tariffs are a separate type of tariff from the tariffs imposed via IEEPA” and that the Court’s ruling “does not directly affect those measures.”

The Budget Lab at Yale likewise noted that the administration retains authority to pursue tariffs under Sections 201, 232 or 301, or temporarily invoke Section 122, which allows tariffs up to 15% for 150 days without investigation.

Over time, expanded investigations under those statutes could construct a tariff regime roughly comparable in scale to the one dismantled by the Court.

Construction Exposure and Industry Reaction

Even with IEEPA tariffs invalidated, the overall effective tariff rate is projected to fall but remain historically elevated because existing Section 232 duties and the new Section 122 surcharge remain in place.

The Budget Lab projects short-term consumer prices will rise 0.6%, or roughly $800 per household in 2025 dollars, and models long-run GDP 0.1% smaller under the remaining tariff structure. Construction output contracts 2.4% in the long run, even absent IEEPA tariffs.

Section 232 tariffs on steel and aluminum remain in place, preserving exposure across rebar, structural plate, fabricated steel, curtain wall systems, heavy equipment and building systems components.

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ENR reported in 2018 that Section 232 tariffs triggered double-digit swings in structural steel pricing, complicating procurement schedules and escalation clauses on transportation and energy megaprojects. Similar volatility resurfaced during renewed trade actions in 2025.

Associated Builders and Contractors Chief Economist Anirban Basu said the ruling could ease pressure on finished component prices.

“Now that the U.S. Supreme Court has overturned IEEPA tariffs, the construction industry could see a modest but meaningful reduction in materials price escalation, specifically for manufactured components like specialty equipment, HVAC and electrical systems, and fixtures,” Basu said in an email to ENR.

But, he cautioned, that relief may prove temporary.

“Of course, the administration has signaled that plans are in place to replace at least some of those tariffs through other means, so the benefits could be short-lived and completely counteracted by heightened uncertainty during the transition from one tariff mechanism to another,” Basu said.

The administration formalized that shift Feb. 20 under Section 122, and Trump has since suggested the surcharge could rise to the statute’s 15% ceiling — a move that would deepen cost exposure on non-exempt imports.

“That, combined with the fact that the Section 232 tariffs on raw inputs like steel and aluminum will remain in place, means that this Supreme Court ruling could ultimately be less consequential for the construction industry,” Basu added.

AGC’s Turmail said that, unless new tariffs are imposed under another legal rationale, “contractors should expect to see some relief in materials costs in the near term,” although longer-term pricing will depend on how the administration restructures its trade program.