Polymarket odds soften as Supreme Court weighs tariffs

Answer: Indicators currently favor a Supreme Court ruling against the tariffs

Prediction-market signals currently point to roughly a three-in-four probability, about 74%, that the Supreme Court will rule President Trump’s tariffs illegal, based on data summarized by Ainvest from Kalshi and Polymarket. The direction of travel in these markets has been consistent with a negative outcome for the tariffs rather than an affirmance.

Timing remains uncertain. According to Kalshi’s news desk, traders recently priced only about 32% odds that a decision would arrive this week, underscoring that the ruling could drop any day rather than on a fixed schedule.

Why odds lean negative: IEEPA, major-questions doctrine, and Kalshi pricing

The International Emergency Economic Powers Act (IEEPA) lets a president regulate certain cross‑border transactions during a national emergency, but whether it authorizes broad, across‑the‑board import tariffs is the core statutory dispute. Under the Supreme Court’s major‑questions doctrine, actions of vast economic significance require clear congressional authorization; Cato Institute commentary argues that the asserted IEEPA authority for sweeping tariffs is unlikely to meet that standard.

Legal reasoning offered by prominent advocates has emphasized the constitutional allocation of tariff and tax powers to Congress, reinforcing the statutory concerns. “Tariffs are taxes,” said Neal Katyal, former Acting U.S. Solicitor General, arguing that unilaterally imposed duties risk exceeding both statutory and constitutional bounds.

Market indicators align with that legal posture. As reported by Yahoo News, Polymarket odds of a Supreme Court win for the tariffs have been sliding in the days leading up to the decision, signaling traders’ growing skepticism about the durability of the IEEPA-based duties.

What a negative ruling could mean for refunds and businesses

If the Court rules the IEEPA tariffs illegal, refunds for previously collected duties are possible but not assured; outcomes would depend on the remedy the Court orders and subsequent implementation by the relevant agencies. As reported by Politico, Treasury Secretary Scott Bessent has acknowledged the government could be forced to issue large refunds, possibly tens of billions, if the tariffs fall, though the ultimate magnitude and timing would be conditional on the decision’s scope.

For small businesses, the direction is consequential. As reported by Kiowa County Press, the U.S. Chamber of Commerce estimated that tariff policies cost roughly 236,000 small businesses about $200 billion annually, implying that an adverse ruling against the tariffs could relieve a substantial expense burden if duties are unwound and eligible refunds are processed.

Legal scholars have also cautioned that any refund pathway may be complex and uneven across cases, reflecting differences in litigation posture and administrative steps. Analyses by Kathleen Claussen of Georgetown University and Timothy Meyer of Duke Law emphasize that even with a clear ruling, practical recovery and compliance timelines could vary.