They have filed a suit against Governor Jack Markell and the Delaware State Lottery Office. sports betting in federal court in Delaware.
The country's smallest state is trying to take advantage of an opening in the Professional and Amateur Sports Protction Act of 1992, which prohibits states from bookmaking. There's an exemption in that federal law which allows four states, Nevada, Oregon, Montana and Delaware, which are states that had lottery and other forms of sports gambling in 1992, to resume that practice.
The leagues are contending that Delaware had parlay betting during that time but didn't have single game gambling. The Delaware governor wants to have parlay betting (picking a series of games as a single bet) and single-game wagering in order to attract as much money to the state as possible.