Lawyers for a gun maker and families of some Sandy Hook Elementary School massacre victims squared off in a Connecticut courtroom Monday over whether a federal law prevents the families' wrongful death lawsuit targeting the AR-15 rifle used to kill 20 children and six adults in the 2012 shooting.

Attorney Joshua Koskoff, who represents a group of families of the Sandy Hook Elementary school shooting victims, speaks during final arguments in Superior Court, in Bridgeport, Conn., Monday, Feb. 22, 2016. Ned Gerard / Hearst Connecticut Media via AP

Judge Barbara Bellis in Bridgeport heard arguments but didn't issue a ruling Monday. She said she would rule within the next two months on whether the lawsuit should go forward toward trial or be dismissed.

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The families of nine children and adults killed at the Newtown school and a teacher who survived the attack say the AR-15 is a highly lethal military weapon that should not be sold to the public. They're suing Freedom Group, the Madison, North Carolina, parent company of Bushmaster Firearms, which made the AR-15 used in the school shooting.

Lawyers for Freedom Group said the company is protected by a 2005 federal law that shields gun manufacturers from most lawsuits over criminal use of their products. They said Congress passed the Protection of Lawful Commerce in Arms Act after determining such lawsuits were an abuse of the legal system.

Joshua Koskoff, a lawyer for the victims' families, said their lawsuit is believed to be the first to be filed under an exception listed in the federal law that allows litigation against companies that know, or should know, that their weapons are likely to be used in a way that risks injury to others. The families are seeking unspecified monetary damages and hope the lawsuit persuades gun companies to not sell AR-15s to the public.

"This is an instrument of war designed for the battlefield that is marketed and sold to the general public," said Mark Barden, whose son Daniel was killed in the massacre. "We're just asking for accountability."

State police say Lanza, 20, killed his victims with a Bushmaster XM15-E2S rifle, an AR-15 model, on Dec. 14, 2012. Lanza killed his mother, Nancy Lanza, at their Newtown home with a different gun before going to the school a few miles away, and then killed himself as police arrived. Nancy Lanza legally bought the rifle, state police said.

Gun rights advocates posted to social media and gave interviews with traditional media Monday criticizing the Newtown families' lawsuit.

"It is unconscionable for plaintiffs to assert that a company who manufactures a legal product would do so with any fore-thought that it was somehow acceptable to commit murder with their products," Scott Wilson, president of the Connecticut Citizens Defense League, told Hartford-area station WFSB-TV.