A lawsuit designed to upend the expansion of casino gambling that Maryland voters approved in November got its day in court Tuesday.

Opponents of the successful ballot measure – expected to give rise to a Las Vegas-style casino at National Harbor, and to allow table games there and at a handful of other casinos statewide – say the wording of the measure was unconstitutional.

The lawsuit, which gambling proponents have downplayed as a Hail Mary attempt to stop the law, boils down in part to the measure’s use of the phrase “qualified voters.”

Former Prince George’s County Council member Tom Dernoga argued before Anne Arundel County Circuit Court Judge Ronald A. Silkworth on Tuesday that the casino measure should only be valid if approved by a majority of “qualified voters” – all of those registered and eligible to vote, not just the ones who turned out to the polls.

Lawyers for the state and gambling interests, including MGM Resorts, which aims to build an $800 million casino at National Harbor, argued that Dernoga’s reading of the law misrepresented lawmakers’ intent.

Maryland Assistant Attorney General Julia Doyle Bernhardt said the language – used in 18 states – was only intended to refer to voters who turned out to vote.

Timothy F. Maloney, a former state lawmaker and one of seven attorneys arguing against the lawsuit, said that if Dernoga’s reading was true, 76 percent of all voters who cast ballots in November would have had to vote in favor of the measure for it to pass. In less-well-attended elections, more voters than all those that go to the polls would be needed to successfully pass a measure.

Dernoga represents eight Prince George’s County residents named as plaintiffs. Silkworth could rule as early as next week.