The maker of the gun used in the 2012 massacre of 26 young children and educators at a Connecticut elementary school will ask a judge to toss a lawsuit saying the weapon never should have been sold to a civilian.

Bushmaster Firearms LLC, which manufactures the AR-15 that 20-year-old Adam Lanza used in his attack on Sandy Hook Elementary School in Newtown, said a 2005 federal law prohibited gunmakers from being sued when their products are used to commit crimes.

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The families of nine people who died in the attacks sued Bushmaster in 2014 in Connecticut Superior Court in Bridgeport. The lawsuit said the AR-15 should never have been sold to the gunman’s mother, Nancy Lanza, because it had no legitimate civilian purpose.

Judge Barbara Bellis, who has set an April 2018 trial date, will hear arguments on Monday, eight days after a gunman armed with another model of assault rifle, a Sig Sauer MCX, killed 49 people at a gay nightclub in Orlando, Florida, in the deadliest mass shooting in modern U.S. history.

Bushmaster, as well as the wholesaler and retailer involved in the sale of the Sandy Hook gun, said the 2005 Protection of Lawful Commerce in Arms Act exempted it from lawsuits for having legally sold the gun to Nancy Lanza in 2010.

“No amount of rhetoric from plaintiffs should cloud the plain language of the PLCAA and frustrate congressional intent to protect firearm manufacturers from claims that they negligently entrusted lawfully manufactured firearms that were later used by criminals to cause harm,” Bushmaster said in a court filing ahead of Monday’s hearing.

Boston College Law School professor Robert Bloom said the federal law gave the companies a strong defense, but the judge appeared to be open to the families’ position.

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“They have an uphill battle, but given the climate and the judge’s previous rulings, it seems that she is sympathetic to the argument,” Bloom said.

Following the Sandy Hook shooting, congressional Democrats tried unsuccessfully to pass stricter national gun laws.

The Senate, however, agreed last week to vote on gun control measures following a 15-hour filibuster by Democrats.

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Adam Lanza began his Dec. 14, 2012, attack by shooting his mother dead in their home and ended it by turning his gun on himself as he heard police sirens approach.

(Reporting by Scott Malone in Boston; Editing by Lisa Von Ahn)