A federal judge in Baltimore will hear a challenge to Maryland's new gun-control law Tuesday, the same day the measure containing some of the nation's tightest firearm restrictions is scheduled to take effect.



The U.S. District Court hearing was ordered Friday, one day after opponents filed a lawsuit claiming the law was passed in ``flagrant disregard'' of Second Amendment rights.



The lawsuit was filed by a number of people, including two retired veterans who are Maryland residents, gun stores, the Maryland State Rifle and Pistol Association and the Maryland Licensed Firearms Dealers Association. It seeks to block implementation and, ultimately, to have the court permanently bar Maryland from enforcing the law.



Earlier this year, Maryland Attorney General Doug Gansler issued a 25-page legal review expressing confidence that the law is constitutional and legally defensible. But opponents, including the National Rifle Association, announced when the law was signed in May that they would challenge it in court.



A spokeswoman for Democratic Gov. Martin O'Malley expressed confidence that the law would survive the challenge.



``The vast majority of Marylanders support these common-sense efforts to reduce gun violence. The new law will take effect on Tuesday and it will make families safer,'' spokeswoman Samantha Kappalman said Friday.



Gansler spokesman Alan Brody declined to comment on the lawsuit. The state's response to the complaint is due by noon Monday.



Plaintiffs' attorneys John Parker Sweeney and Tara Sky Woodward wrote in their 34-page filing that the law restricts ``the ability of law-abiding, responsible citizens'' of Maryland ``to defend themselves, their families, and their homes by prohibiting outright certain commonly used rifles and shotguns and standard capacity ammunition magazines.''



The law signed by Maryland Gov. Martin O'Malley law adds 45 types of guns to a list of banned assault weapons and limits handgun magazines to 10 rounds. O'Malley proposed the bill in response to the December shooting in Newtown, Conn., where a gunman killed 20 children and six adults.



The lawsuit prominently cites the U.S. Supreme Court's 2008 decision involving gun rights, District of Columbia v. Heller. The court announced in that case that the Constitution protects an individual's right to possess handguns, at least for self-defense in the home. But it left open the question of how broadly the Second Amendment protects gun rights in other settings.



Constitutional scholar Adam Winkler, a law professor at the University of California at Los Angeles, said the challenge probably won't succeed.



``What we've seen is that challenges to gun control like this in the past have inevitably failed,'' Winkler said.



Although the Supreme Court hasn't ruled on either assault-weapon bans or bans on high-capacity magazines, Winkler said every lower court ruling on those issues has upheld the restrictions.



James B. Jacobs, a New York University law professor and constitutional scholar, agreed that Maryland's ban on high-capacity magazines would likely survive the challenge. But he said the plaintiffs probably have a good argument that the state has arbitrarily defined certain guns as assault weapons.



``I think there has to be a burden to show that the type of guns they're prohibiting are somehow different, unusual and in a class by themselves, and don't infringe too much on the choices of weapons that people can make,'' he said.



The law also requires people to submit fingerprints to the state police to get a license to buy a handgun. The lawsuit doesn't challenge that provision.

