Speaking at the Casa news conference, Exelby said states such as California that frequently see ballot initiatives have taken a "go slow" approach to electronically created petitions.
Questions about the legality of the MDPetitions.com website were first raised by the American Civil Liberties Union of Maryland, which sent a detailed critique to the Maryland State Board of Elections in May. The group did not sign onto the lawsuit.
Meredith Curtis, the group's outreach director, said in a statement that the ACLU believes the process is "extraordinarily vulnerable to fraud" which would be "almost impossible to detect."
She said that her group's absence from the suit "does not reflect any change of opinion" but instead indicates a belief that Casa "has a large and able legal team."
Casa also argues in the lawsuit that the in-state tuition bill is a budget-related bill, and therefore falls into a special category of Maryland laws that are immune from petition challenges. A similar legal argument was used in 1987 to nullify a petition drive opposing construction of Oriole Park and Ravens Stadium at Camden Yards.
Casa's lawyers filed the suit on the last day that it could be accepted. They said they based their analysis on the first batch of 47,288 valid signatures filed by opponents at the end of May.
Casa's lawyers said they had not yet examined all 108,645 signatures submitted, but projected that if a judge accepts their arguments, the petition drive is about 4,500 valid signatures short of the number needed to trigger the referendum.
Discrepancies with the projections already have arisen: Casa suit estimates that 43,811 signatures came through the website. The State Board of Elections, which has reviewed all of the petitions, puts the figure at 35,506.
The difference could prove critical: Using the state board's numbers, the petitioners still would have more than enough signatures even if all of the Internet-generated forms are tossed.
Washington attorney Joe Sandler, representing Casa, said staff went though the petitions "line by line" and found "a lot more" computer-generated pages than the state elections board had reported.
"Our belief is the local boards just missed a bunch," said Sandler, who specializes in election law and counts the Democratic National Committee as a former employer.
Sandler also wants the court to throw out about 10,000 petitions that did not have the in-state tuition law printed on the reverse side, which he says is required by law. In many cases a copy of the law was stapled to the reverse side.
Maryland laws are rarely petitioned to referendum successfully. The last one to be certified by the State Board of Elections was a gay rights law that passed in 2001; the board's certification was successfully challenged by the ACLU.
Thousands of petitions were jeopardized after a judge heard testimony that the petition-gatherers failed to witness each signature — and the petition organizers abandoned their effort.
A state-passed law has not made it to the ballot since 1992, when opponents sought to overturn a measure affirming a woman's right to abortion. Voters upheld the law.