Baltimore filed lawsuits against prediction market platforms Kalshi and Polymarket on 13 August 2025, accusing them of offering illegal sports betting without Maryland state licences. It is the first time a US municipality has sued prediction market operators.
The suit against Kalshi also names Robinhood, Webull and Coinbase as co-defendants for offering Kalshi contracts through their platforms. Baltimore cites its Consumer Protection Ordinance, claiming the companies created a 'false and misleading impression' about the legality of their products in the state. Maryland's regulator had already issued a cease-and-desist order to Kalshi in April 2025, finding that purchasing sports contracts was 'indistinguishable from placing a bet'. Kalshi filed a counter-suit in federal court but was denied a preliminary injunction in August; the case is now on appeal.
The Polymarket complaint highlights risks to users: insider trading, manipulation and the presence of professional traders. Baltimore argues Polymarket now uses lines, spreads, prop bets and parlays, increasingly resembling a traditional sportsbook. Both platforms accept customers from 18, while licensed betting in Maryland requires users to be 21.
The city is seeking to block transactions from Baltimore residents, recover funds for affected customers, confiscate 'illegally obtained revenue' and impose fines of $1,000 per violation. Each day a violation continues counts as a separate offence.
This marks Baltimore's third wave of legal action against the gambling industry in eighteen months. In April 2025 the city sued DraftKings and FanDuel for exploiting problem gamblers; in March it went after six sweepstakes casinos, including VGW and High 5 Games, for disguising gambling as lotteries.
