Every Bilateral Trade Deal Trump Negotiated Last Year Was Built on IEEPA Authority That No Longer Exists, and America's Allies Are Starting to Recalculate

The Supreme Court's 6-3 decision on Thursday evening striking down President Trump's use of the International Emergency Economic Powers Act to impose tariffs was, in the most immediate sense, a story about trade policy. Within hours, markets rallied, economists recalculated consumer price projections, and the administration scrambled to find alternative legal authority. But the ruling's most consequential ripple effect may not be felt in the American economy at all. It may be felt in the foreign ministries and presidential offices of every country that signed a bilateral trade deal with the United States over the past year.

Those deals, negotiated under the explicit threat of IEEPA-authorized tariffs, are now built on a legal foundation that the highest court in the land has declared unconstitutional. And the countries that made painful concessions to secure relief from those tariffs are beginning to ask a question that Washington would prefer they did not: if the tariffs were illegal, are the deals still binding?

The South Korea Test Case

No country illustrates the dilemma more clearly than South Korea. In November 2025, Seoul agreed to a sweeping bilateral deal that reduced tariffs on Korean goods from 25% to 15% in exchange for a staggering $350 billion commitment of South Korean investment in the United States. The agreement was hailed by the Trump administration as a model for the new trade order. Korean companies pledged to build semiconductor fabrication plants, expand automotive manufacturing, and invest in American energy infrastructure.

Industry Minister Kim Jung-kwan held an emergency meeting on Saturday to assess the ruling's implications. The Ministry of Trade, Industry and Resources issued a statement noting that the Supreme Court's decision "renders void the 15% reciprocal tariff currently applied to Korean goods." But the ministry stopped short of declaring the broader deal intact. Instead, the presidential office released a carefully worded statement saying the government would "review the trade deal and make decisions in the national interest."

The diplomatic language is unmistakable: South Korea is keeping its options open. The $350 billion investment commitment was extracted under duress, with the threat of 25% IEEPA tariffs serving as the stick. If that stick has been declared illegal, the incentive to honor the full commitment diminishes substantially, particularly for a country whose domestic politics have shifted in favor of leaders who opposed the deal from the start.

The Legal Vacuum

The core problem is structural. Every bilateral trade deal the Trump administration negotiated in 2025 followed the same playbook: impose punitive tariffs under IEEPA, then offer to reduce them in exchange for investment commitments, market access, or other concessions. Japan, India, Vietnam, Brazil, and the European Union all entered negotiations under this framework. Some reached agreements. Others were still negotiating when the Court issued its ruling.

International trade lawyers are now wrestling with a question that has no clear precedent. In domestic law, contracts signed under duress are voidable. But bilateral trade agreements exist in a gray area between domestic law and international treaty obligations. They are typically structured as executive agreements rather than formal treaties, meaning they do not require Senate ratification and derive their enforceability from the executive branch's authority to regulate trade.

If that authority, at least as exercised through IEEPA, has been struck down, the agreements themselves may be vulnerable to legal challenge. More practically, they may simply be impossible to enforce politically. A foreign government that signed a deal to avoid illegal tariffs has every incentive to slow-walk its commitments while publicly expressing continued support for the partnership.

Europe's Tactical Silence

The European Union's response has been notably muted, and trade analysts say that restraint is deliberate. European leaders spent much of 2025 negotiating under the threat of IEEPA tariffs, and the process left deep scars. The European Commission had prepared retaliatory tariffs on American goods, including bourbon, motorcycles, and agricultural products, that were never implemented because the threat of escalation was deemed too costly.

Now that the legal basis for the American tariffs has been invalidated, Brussels finds itself in an unexpectedly strong position. The 15% Section 122 tariff that the President imposed as a replacement is capped by statute, temporary by law, and widely expected to face its own legal challenges. European officials are reportedly waiting to see whether the replacement tariff survives before deciding how to proceed with their own trade posture.

"Europe is in no rush to renegotiate anything," said one senior trade official in Brussels, speaking on background. "The leverage has shifted. We are going to be patient and see what legal authority the United States actually has before we make any commitments."

The Section 122 Replacement and Its Limits

President Trump moved with remarkable speed after the ruling, invoking Section 122 of the Trade Act of 1974 to impose a 10% global tariff on Friday evening, then raising it to the statutory maximum of 15% on Saturday morning. But Section 122 comes with constraints that IEEPA did not. The tariff is explicitly temporary: 150 days from its effective date of February 24, after which Congress must act to extend it. The law was designed for balance-of-payments emergencies, and multiple legal scholars have already argued that the current trade deficit does not qualify.

For America's trading partners, the 150-day clock changes the calculus entirely. Under IEEPA, the tariffs had no expiration date and could be raised unilaterally. The permanence of the threat gave the administration enormous leverage. Under Section 122, the tariffs are time-limited and face immediate legal challenge. A country that was willing to make a $350 billion concession to avoid permanent 25% tariffs may be far less willing to honor that commitment to avoid temporary 15% duties that may not survive their first court hearing.

What This Means for American Trade Policy

The administration has framed the Supreme Court ruling as a minor procedural setback, arguing that the same tariff outcomes can be achieved through alternative legal authorities. But the reality is that the ruling has fundamentally altered the power dynamics of American trade negotiations. The United States can still impose tariffs, but the ceiling is lower, the duration is shorter, and the legal foundation is shakier.

For American businesses that have been planning investments based on the assumption that bilateral trade deals would hold, the uncertainty is deeply unsettling. Companies that committed to reshoring supply chains in response to favorable trade terms are now asking whether those terms will survive. Companies in allied countries that committed to investing in the United States are asking the same question.

The Supreme Court struck down the tariffs. It may also have inadvertently struck down the trade deals they were designed to produce. And the scramble to figure out what replaces them is only beginning.