If successful, the lawsuit could nullify the results of Question 7 on Tuesday.
The suit argues that in order for Question 7 to pass, the majority of all registered voters, not just those who turn out to vote, would need to approve the measure. The suit names Gov. Martin O'Malley, Attorney General Doug Gansler, the State Board of Elections and others as defendants.
"There has been some confusion created about the standard required to certify the election result," Dernoga said.
Dernoga's claim is based on the language of the constitutional amendment that legalized casinos four years ago.
The language at question is from Article XIX, Section 1(e) of the state constitution, which reads:
"The General Assembly may only authorize additional forms or expansion of commercial gaming if approval is granted through a referendum, authorized by an act of the General Assembly, in a general election by a majority of the qualified voters in the State."
The suit argues that the term "qualified voters" means all registered voters, not just those who actually go to the polls on Election Day.
"I'm amazed it has taken this long for someone to have done this," said Todd Eberly, political science professor at St. Mary's College of Maryland. "It is so painfully obvious."
In the last presidential election, 78 percent of registered voters in Maryland went to the polls. If there is a similar turnout in this election, about 65 percent of people who actually vote would need to be in favor for the measure to get a majority of registered voters.
Polls leading up to the election show voters are evenly split on the gaming question.
Eberly said that if Question 7 passes Tuesday, he would expect a judge to put a hold on it until a hearing is held.
"Unless a judge, for blatant political reasons, wants to ignore the plain language of the constitution, it would be impossible to dismiss that," Eberly said.
Gansler's office declined to comment, but forwarded two letters which discussed the issue. One, a letter sent to House Speaker Michael Busch in 2011 by Dan Friedman, counsel to the General Assembly, rejects the interpretation that all registered voters must be counted. The letter reads:
"Thus, it is our view that only a majority of the votes cast in favor of the expansion of gaming is needed for it to be adopted."
In another letter, sent in 2007, Assistant Attorney General Bonnie Kirkland said it was her view that "the language requires a majority of votes cast on the question."
The campaign fight over expanding gambling has amassed close to $80 million in contributions so far, largely between the company hoping to open a casino at National Harbor, MGM Resorts International, and the company hoping to protect its interests in West Virginia, Penn National Gaming. Experts have said the money invested in the campaign will be well spent for whoever wins, but depending on the outcome of this lawsuit, both companies could leave Maryland with a little less cash.