The end of Trump's unilateral tariff policy? Legal, political, and geoeconomic analysis of the Supreme Court's historic ruling on presidential powers

On February 20, the US Supreme Court issued its final ruling, definitively invalidating the comprehensive tariff system launched by the Trump administration. The Executive's strategy, centered on invoking a state of national emergency to justify the widespread imposition of tariffs, was deemed entirely unconstitutional. The scope of this decision transcends the mere repeal of an economic trade program, constituting rather an unprecedented institutional clash and a peremptory reminder of the intrinsic limits of presidential power within the American constitutional order. The process was completed exceptionally quickly by constitutional standards, taking a total of around eight months. The legal proceedings began with the first petition filed on June 17, 2025, and concluded definitively with the historic ruling on February 20, 2026.

The U.S. Supreme Court - GettyImages

This historic decision strikes at the heart of the American institutional balance, as the focus of this ruling is not tariffs but power and its distribution. During its second term, the administration's strategy was divided into two main areas. On the one hand, the United States imposed a universal 10 percent tariff on almost every country in the world, citing the need to correct long-term trade deficits. On the other hand, much higher tariffs were imposed on Canada, Mexico, and China on the grounds that they had failed to effectively prevent the flow of fentanyl into US territory. The President argued that opioid-related deaths and the persistent trade deficit constituted a national emergency and that this status gave the executive branch the authority to take extraordinary economic measures. However, the Supreme Court ruled that this logic clearly exceeded the statutory authorization granted by Congress, rendering both types of tariffs invalid.

Analyzing the issue from a legal standpoint, the majority opinion drafted by Chief Justice John Roberts reaffirms the bedrock principles of the US constitutional framework. In the American system, the power to levy taxes rests exclusively with Congress, and while the President can enforce laws, he has no inherent prerogative to impose taxes independently or to circumvent legislative power by abusing a state of emergency.

The law invoked by the administration, namely the International Emergency Economic Powers Act of 1977, does not in any way grant the executive branch the power to unilaterally impose large-scale tariffs.

Roberts wrote clearly that if the legislature intends to delegate special powers to impose tariffs, it will make this clear through unequivocal statutory language. The Court applied the doctrine of major questions in this context, ruling that the term "regulate imports" in the emergency legislation is not sufficient to include the vast and incisive power of taxation.

This strict interpretation found broad institutional support, and it is interesting to note that the ruling was approved by a majority of three conservative and three progressive judges. Justices Sotomayor, Kagan, Gorsuch, Barrett, and Jackson joined the main opinion in various parts. The internal dynamics of the Court proved to be complex, as Justice Kagan filed a concurring opinion together with Sotomayor and Jackson, arguing that a literal interpretation of the text of the law was sufficient without necessarily resorting to additional interpretative doctrines. Justice Jackson also delved into the legislative history of the law to highlight the clear lack of original taxing intent. On the opposite side, the dissent expressed by Thomas, Alito, and Kavanaugh shows that within the conservative camp itself, there are deep divisions and differing interpretations regarding the expansion of executive power, especially when commercial dynamics merge with national security and foreign policy. From a procedural point of view, the initial district court ruling was overturned and remanded with instructions to dismiss for lack of jurisdiction, while the Court of Appeals' decision was upheld in its entirety.

Shifting the focus to the geo-economic and geopolitical level, the ruling has immediate effects and opens up complex scenarios, making it necessary to distinguish between the factual consequences of the ruling and analytical considerations on future dynamics. In practical terms, the use of universal tariffs as a tool for macroeconomic pressure has been discontinued. The administration had conceived this measure to reduce the national deficit and encourage the renegotiation of international agreements through the use of tariffs. The annulment of this regulatory framework could now force the US Treasury to address the delicate issue of refunds for the billions of dollars already collected in the absence of a valid constitutional basis. As explicitly emerged during the trial, this procedure promises to be extremely complex and difficult to manage administratively. In terms of future prospects, the removal of this emergency lever could generate uncertainty about the stability of global trade agreements recently signed or renegotiated with key partners such as the United Kingdom and Japan, agreements in which tariffs had played a major role in negotiations. At the same time, at a systemic level, the Supreme Court's intervention tends to reassure international markets and long-standing partners by restoring greater legal certainty. The decision clarifies that the imposition of structural tariffs requires an explicit legislative mandate and cannot be based on broad or unilateral interpretations of national emergency powers.

Deprived of unilateral enforcement, President Trump now finds himself forced into a difficult strategic political repositioning. In order to attempt to restore his tariff system, he will necessarily have to go through Congress in search of a complex legislative "ratification": a path fraught with negotiating obstacles and potential bipartisan resistance, which transforms what was once an agile emergency measure into a grueling test of his parliamentary strength.