Prediction markets have lowered the likelihood of President Trump prevailing in a key Supreme Court case concerning his tariff authority to just 24 percent. The case, centered on the legality of tariffs imposed under the International Emergency Economic Powers Act (IEEPA), has drawn national attention due to its potential to redefine executive control over trade policy.
The Supreme Court heard oral arguments in early November 2025. Multiple justices signaled doubt over whether the IEEPA grants the president authority to impose tariffs without direct congressional approval. Questions from Chief Justice John Roberts and Justices Amy Coney Barrett and Neil Gorsuch focused on whether the law was intended to permit such broad economic actions, or merely authorize sanctions and embargoes in times of national emergency.
Following the hearing, trading activity on prediction markets responded sharply. Kalshi and Polymarket both reported steep declines in the probability of a favorable ruling for the Trump administration, dropping to roughly 24 percent. These platforms reflect real-time sentiment among political analysts, legal observers, and market participants.
The Trump administration has defended its interpretation of IEEPA as consistent with longstanding presidential discretion in foreign policy and national security matters. Supporters argue the tariffs were a necessary tool to counter unfair trade practices and protect American industries. Critics contend the approach bypassed congressional authority and may set a precedent for unilateral executive action on economic issues.
A ruling against the administration could invalidate significant portions of the tariffs and prompt future limitations on executive power. It may also affect revenue generated through duties imposed under the policy.
The case represents one of the most consequential legal tests of presidential trade authority in recent history. With a decision expected in the coming months, the outcome could reshape how future administrations leverage emergency powers in economic matters.
