The head of the nation's largest gun lobbying group said Tuesday that the organization plans to sue Maryland to prevent Gov. Martin O'Malley's sweeping new restrictions on so-called assault weapons from taking effect.

The General Assembly passed the ban last week and is waiting for O'Malley to sign it, but National Rifle Association President David Keene said the NRA is already preparing for a court fight. In addition to an assault weapon ban, Maryland lawmakers voted to require gun buyers to be fingerprinted and to undergo gun-handling training and to limit the size of ammunition magazines.

"Much of it's foolish, some of it's unconstitutional, and other portions of it simply put burdens on honest citizens who have every right under the Second Amendment to own and use firearms for legitimate purposes," Keene said on WTOP.

The Maryland bill prohibits the sale, ownership and transportation of 45 types of assault weapons and limits ammunition magazines to 10 rounds. The legislation follows a national push by President Obama and Democrats to restrict gun ownership in the wake of a mass shooting in December at a Connecticut elementary school.

A blanket ban on the AR-15, one of the most popular guns in America and the weapon used by shooter Adam Lanza to kill 20 young children and six adults in Newtown, Conn., violates a 2008 U.S. Supreme Court decision that "one kind of firearm that cannot be banned is one that's commonly owned and widely used for legitimate purposes," Keene said.

O'Malley, a Democrat who championed the legislation and is expected to sign it, expressed confidence that the restrictions will survive legal challenges.

"We believe, as does [Attorney General Doug Gansler], that our new law is constitutional," said O'Malley spokeswoman Raquel Guillory. "We currently have a ban on enumerated assault pistols, which has been on the books for decades."

The NRA already sued New York state after Gov. Andrew Cuomo ushered in similar restrictions on military-style weapons through his state legislature. Both Cuomo and O'Malley are considered potential Democratic presidential nominees in 2016.

Mark Graber, associate dean at the University of Maryland Francis King Carey School of Law, said it was to be expected that the NRA would sue any time a state acts to restrict gun ownership. Less certain as the debate comes to a head is whether those laws will be upheld.

"There's good reason to think that fairly strict laws, particularly on automatic weapons, get through the lower courts. What will happen in the Supreme Court is just anybody's guess," Graber said. "There are an amazing amount of cases bubbling up in the circuit courts, and at some point, the Supreme Court will take one of them. I predict we'll have a major Supreme Court ruling on guns in the next two to three years."