38 State Attorneys General Back Massachusetts in Lawsuit to Shut Down Kalshi's Sports Betting

A bipartisan coalition of 38 state attorneys general just filed an amicus brief backing Massachusetts in its lawsuit against Kalshi, the prediction market platform that's quietly become one of the biggest sports betting operations in the country.

Massachusetts Attorney General Andrea Joy Campbell first sued Kalshi in September 2025, alleging the company runs an unlicensed sportsbook disguised as a "prediction market." In January 2026, a Massachusetts judge granted a preliminary injunction blocking Kalshi from accepting sports wagers from state residents. The case is now in front of the Massachusetts Supreme Judicial Court, and a coalition of 38 AGs — led by Nevada's Aaron Ford and Ohio's Dave Yost — wants the court to keep that injunction in place.

The brief argues Kalshi is using "event contracts" to take bets on game winners, point spreads, college sports, and other outcomes without the licensing, age requirements, or tax obligations that legal sportsbooks have to follow. The AGs say that from January to June 2025, users wagered more than $1 billion every month on the platform, and roughly 90% of that was tied to sports.

Washington Attorney General Nick Brown filed his own civil lawsuit against Kalshi on March 27, 2026, claiming the company violates Washington's Gambling Act and Consumer Protection Act. The state is seeking to halt Kalshi's operations in Washington, recover money lost by state residents, and impose civil penalties. Kalshi's response has been the same in every state: as a platform regulated by the Commodity Futures Trading Commission (CFTC), the company argues federal law overrides state gambling rules.

This is on top of an existing nationwide class action lawsuit filed by Kalshi users in New York federal court last November, which alleges the platform deceived consumers into thinking they were betting against other users when they were actually betting against Kalshi-affiliated market makers and partnered hedge funds. We covered that case here.

How this affects you

If you live in Massachusetts, Kalshi is already blocked from offering sports contracts to you. If you live in Washington, the state is trying to do the same and recover money you may have lost on the platform. With 38 attorneys general now formally aligned against Kalshi, the legal pressure is only growing. The case will likely end up at the U.S. Supreme Court, and the outcome could reshape the entire prediction market industry.

If you've spent money on Kalshi sports contracts, you may be eligible to recover some of it through the existing class action or future state-level settlements.

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