What are Supreme Court decision markets?
Supreme Court decision markets are prediction markets that let people trade on outcomes involving the U.S. Supreme Court (SCOTUS). Instead of guessing who’ll win an election, traders bet on things like:
Whether the Court will uphold or strike down a law or policy
Whether there will be a vacancy or a new justice by a deadline
How many justices will vote a certain way
Platforms like Polymarket and Kalshi now run multiple SCOTUS markets. Examples include:
“Supreme Court rules in favor of Trump’s tariffs?” with over $1M in volume on both Polymarket and Kalshi
“Supreme Court vacancy in 2025?” or “Who will be the next Supreme Court justice?” tracking retirements and appointments
These markets turn complex legal disputes into simple $1 contracts whose prices you can read as probabilities.
Where are SCOTUS markets traded?
Today, Supreme Court decision markets mainly live on:
Polymarket – a crypto-based prediction platform that lists “Courts” and “SCOTUS” markets, including the tariff case and vacancy questions. Traders use USDC stablecoins and trade YES/NO shares on-chain.
Kalshi – a CFTC-regulated event-contract exchange that offers markets like “Will the Supreme Court rule in favor of Trump’s tariffs?” and “How many justices will vote for Trump’s tariffs?” as fully collateralized event contracts.
Media outlets now quote these odds just like polling averages: Fox Business, MarketWatch, and Nasdaq have all covered how Kalshi and Polymarket odds on the Trump tariff case plunged after skeptical oral arguments.
How a Supreme Court decision market works
Most SCOTUS markets are binary event contracts:
Example question: “Will the Supreme Court rule in favor of Trump’s tariffs?”
On Kalshi, the contract resolves YES if the Court reverses lower-court rulings in Learning Resources v. Trump / Trump v. V.O.S. Selections and upholds the tariffs by a fixed deadline; otherwise it resolves NO. The outcome is verified from official Supreme Court opinions.
On Polymarket, a similar market pays out based on whether SCOTUS issues a decision that “reverses, vacates, or otherwise overturns” the Federal Circuit’s ruling in V.O.S. Selections, Inc. v. Trump before the end date.
Step-by-step mechanics
Market listing & rules
The platform posts the question, an end date, and detailed rules (which docket, what counts as “in favor,” what happens if the case is dismissed, etc.).
Pricing as probability
Contracts trade between $0.01 and $0.99 (or 1–99 cents on crypto platforms).
A price of $0.24 means the market currently gives about a 24% chance the Court rules that way. Fox Business recently highlighted odds around 24–25% on the tariff case after oral arguments.
Trading during the case
Traders buy or sell based on briefs, lower-court decisions, oral arguments, and analysis of the justices’ prior opinions.
When conservative justices Barrett, Roberts, and Gorsuch signaled skepticism of Trump’s tariff authority, odds of a tariff win fell sharply on both Kalshi and Polymarket.
Settlement after the opinion
Once SCOTUS publishes its decision, the platform checks it against the rules.
Winning contracts pay $1, losing contracts pay $0, automatically from pre-posted collateral.
What kinds of Supreme Court questions do markets cover?
Common SCOTUS market themes include:
Case outcomes
“Will the Supreme Court uphold Trump’s tariffs?”
“Will the Court strike down [specific regulation or statute]?”
Vote counts & coalitions
“How many justices will vote to uphold the tariffs?” with contract ranges like 0–3, 4–5, 6–9.
Personnel & vacancies
“Supreme Court vacancy in 2025?”
“Who will be the next Supreme Court justice?”
Timing
Whether an opinion will be handed down by a specific term or date.
Because SCOTUS sits at the intersection of law, politics, and markets, these questions attract both constitutional-law nerds and macro investors.
Why people trade Supreme Court decision markets
People use SCOTUS markets for three main reasons:
Forecasting legal outcomes
Traders synthesize briefs, precedent, ideological leanings, and prior votes to estimate probabilities for complex doctrinal questions like non-delegation or the major questions doctrine at issue in the tariff case.
Information for investors and businesses
A ruling on tariffs, environmental rules, tech regulation, or agency power can move entire sectors. Financial media now cite Kalshi odds as a way to gauge market expectations ahead of big decisions.
Speculation and hedging
Some traders simply try to profit from price moves around oral arguments or leaks.
Others hedge exposure: e.g., an importer hurt by tariffs might buy contracts that pay if the Court strikes them down.
Empirically, prediction markets have often provided sharper or earlier signals than pundit chatter, which is why journalists increasingly reference them when covering high-stakes cases.
Legal and ethical questions around SCOTUS markets
Supreme Court decision markets sit inside a broader legal tug-of-war over prediction markets:
Federal vs. state regulation: Kalshi argues its contracts are under exclusive CFTC jurisdiction, but states like Nevada and Connecticut say some event markets (especially sports) are unlicensed gambling and must follow state gaming rules.
Will SCOTUS itself step in? Legal analysts and even the Polymarket CEO expect the Supreme Court may eventually have to decide how federal derivatives law and state gambling law apply to prediction markets.
Impact on public trust: Commentators worry that “betting on justice” might erode confidence in the Court, similar to concerns about betting on elections or wars.
So far, there’s no sign that the existence of markets changes how justices decide cases—but the optics are controversial, and future regulation could tighten or loosen what kinds of SCOTUS contracts are allowed.
How to read Supreme Court odds (without overreacting)
If you’re following these markets as a news consumer rather than a trader, a few rules of thumb help:
Treat prices as probabilities, not certainties. A 25% chance is possible, not impossible.
Focus on moves around key events—briefs, oral arguments, leaks—rather than one static number.
Remember liquidity: odds in thin markets can swing wildly on small trades.
Never treat market odds as legal advice or as a guarantee of what the Court “will” do.
In short, Supreme Court decision markets are a new tool for putting numbers on the biggest legal questions in the country. They don’t replace doctrine, precedent, or careful legal analysis—but they do offer a live, incentive-driven readout of what informed traders think the justices are likely to decide.