Prediction markets hold as Supreme Court weighs IEEPA

About 74% odds Supreme Court rules Trump tariffs illegal

Prediction markets currently assign roughly 74% odds that the Supreme Court will rule President Trump’s tariffs illegal under the International Emergency Economic Powers Act (IEEPA). As reported by Cointelegraph, Polymarket and Kalshi have priced roughly 70–80% chances of a strike‑down (https://cointelegraph.com/news/kalshi-polymarket-traders-bet-supreme-court-curb-trump-tariff-powers/?utm_source=openai). These are indicators of expectations, not legal decisions.

Signals from oral arguments also weighed on expectations. The Washington Post noted justices questioned whether IEEPA clearly authorizes tariffs and probed Congress’s taxing power in this context (https://www.washingtonpost.com/politics/2025/11/05/tariffs-trump-supreme-court-arguments/?utm_source=openai). That skepticism is a key reason market odds lean toward illegality.

Why it matters: IEEPA basis, prediction markets, immediate impacts

IEEPA grants emergency authorities to the executive, but its text does not explicitly mention tariffs or duties. The dispute centers on whether Congress delegated tariff authority through IEEPA and how the Court applies separation‑of‑powers and clear‑statement principles. Prediction markets synthesize these legal signals into probabilistic odds that help businesses plan under uncertainty.

On near‑term effects, tariff burdens have been substantial for small firms. The U.S. Chamber of Commerce estimated the policies would cost about $200 billion annually for roughly 236,000 small businesses, as reported by Kiowa County Press (https://kiowacountypress.net/content/small-business-owners-squeezed-tariffs-await-supreme-court-decision). Such costs strain cash flow and pricing flexibility.

Macro measures show the scale of the shift. The average U.S. tariff rate rose from 2.5% to 14.5%, the highest in 87 years, as reported by Seeking Alpha (https://seekingalpha.com/article/4871020-the-impact-of-tariffs-on-the-economy-the-deficit-and-the-consumer). Those dynamics align with accounts of price pressure in household and tech categories. This was reported by The New Republic (https://newrepublic.com/post/206650/thanks-trump-prices-soaring-again-inflation-cost-of-living-affordability).

If illegal: refunds, business costs, and what happens next

If the Court finds the tariffs illegal, exposure could include large refund obligations and operational adjustments for importers and distributors. Scott Bessent, U.S. Treasury Secretary, said the government may need to refund “about half” of collected tariff revenue, as reported by Politico (https://www.politico.com/news/2025/09/07/bessent-half-refund-tariffs-scotus-00549539?utm_source=openai).

Refund mechanics remain uncertain. Multiple experts caution refunds may be partial and procedurally complex, with questions about eligibility, time periods, and legal standing, as reported by Time (https://time.com/7315635/trump-tariffs-supreme-court-refunds-bessent/?utm_source=openai). Timing would depend on the ruling’s scope and any subsequent guidance.

Tariff refunds: who qualifies, documentation, and timing

If tariffs are invalidated, eligibility would likely focus on parties that directly paid duties and can substantiate payments. Commentary highlights disputes over which entries qualify, what documentation is required, and how far back refunds could reach. Observers also caution that not all duties may be refunded even if many are struck down.

Reimposing tariffs under Section 301: constraints and timeline

If IEEPA tariffs fall, the administration could pursue Section 301 of the Trade Act of 1974 to reimpose measures. As reported by Fortune, that pathway would likely be slower and more constrained than emergency powers (https://fortune.com/2025/11/02/trump-tariffs-ieepa-supreme-court-arguments-emergency-powers/?utm_source=openai). Any reimposition would turn on investigative steps and the specific statutory record.