To introduce so-called “reciprocal” tariffs in 2025 — with rates reaching up to 15% on a broad range of imports — the U.S. administration relied on the International Emergency Economic Powers Act (IEEPA). This statute allows the President to take economic measures in the event of an international emergency.

However, the Supreme Court held that the IEEPA could not serve as a legal basis for creating new taxes. According to the majority opinion, the authority to levy taxes and duties lies with Congress. By invoking the IEEPA to impose generalized tariffs, the executive branch exceeded the constitutional limits of its powers.

As a result, the legal foundation of the sweeping tariffs introduced in spring 2025 has been invalidated.

It is important to note, however, that not all tariffs are affected by this ruling. Duties based on other statutory frameworks — particularly those justified on national security grounds (such as tariffs on steel, aluminum, or certain vehicles) — remain intact. The same applies to anti-dumping and countervailing duties, which rely on specific procedural mechanisms.

By contrast, the generalized tariffs adopted under the justification of international economic emergency are now legally vulnerable.

The financial stakes are significant: more than $130 billion is estimated to have been collected in 2025 under these measures. The Supreme Court did not directly address the issue of potential refunds. This matter has been referred to specialized courts, suggesting that lengthy and complex litigation may follow.

The ruling does not signal an abandonment of tariff strategy. In the days following the decision, the U.S. administration invoked another legal basis: Section 122 of the Trade Act of 1974.

This provision allows the temporary imposition of tariffs in the event of balance-of-payments difficulties. On this basis, a global 10% tariff was introduced, with an announced increase to 15%. The maximum duration provided for under this mechanism is 150 days, renewable with congressional approval.

This approach differs from the one based on the IEEPA: it is time-limited and relies on a distinct economic justification. Nevertheless, it demonstrates a clear intention to maintain an active tariff lever.

Beyond its immediate economic impact, the Supreme Court’s decision serves as an institutional reminder. It underscores that even in trade matters, the executive branch must operate within the limits established by Congress.

U.S. trade policy therefore remains marked by tensions, but now within a redefined legal framework. The instruments remain available, yet their use is subject to stricter constitutional scrutiny.

This sequence highlights that debates over tariffs are not confined to economic considerations. They also concern the constitutional balance of powers. And it is precisely on that ground that the Supreme Court chose to rule.