Immigration advocates filed a lawsuit Monday challenging the legality of a petition opposing in-state tuition to illegal immigrants. The petition would put the new Maryland law to voters in a referendum. Filed by Casa de Maryland, a group of students, a parent and a teacher against the state Board of Elections, the suit points to Maryland’s constitution, which says a law that appropriates funding to a government program — as the Maryland Dream Act does — cannot be put to a referendum “precisely to prevent the kind of disruption in government programs and operations that the filing of this petition has caused,” said Joseph Sandler, attorney for the group.

The group also says that more than 57,000 of the 108,923 petition signatures the state body validated on July 22 are invalid. That would put the total number of signatures below the 55,726 needed to put the tuition measure