Casino gambling opponents say Attorney General Martha Coakley was wrong to exclude from the November state ballot a question calling for the repeal of the state's 2011 gambling law.
The group Repeal the Casino Deal filed a 53-page brief with the state's highest court on Friday asking the justices to overturn Coakley's ruling and allow Massachusetts voters to decide the question.
Coakley said in her ruling last fall that the question would violate the state constitution by interfering with "implied contracts" between the state gambling commission and applicants for casino licenses.
But the anti-casino group argues in its legal brief that gambling is known to be a heavily-regulated activity and that casino operators should expect that state laws could change.
The Supreme Judicial Court expects to hear arguments in the case in early May.