The maker of the gun used in the 2012 massacre at Sandy Hook Elementary School is expected to ask a Connecticut judge Monday to toss a lawsuit filed against it by the families of nine of the people who died in the attack, according to court filings.

The lawsuit, filed in December 2014 and seeking unspecified financial damages, said the AR-15 assault weapon used in the attack that killed 20 young children and six educators in Newtown, Connecticut, should never have been sold because it had no reasonable civilian purpose.

Bridgeport Superior Court Judge Barbara Bellis has scheduled a hearing at which privately owned North Carolina-based Bushmaster is expected to ask her to dismiss the litigation, citing the 2005 Protection of Lawful Commerce in Arms Act. The law blocks liability lawsuits against gunmakers when their products were used criminally.

The plaintiffs, including Bill Sherlach, whose 56-year-old wife, Mary Sherlach, was a school psychologist killed in the attack, said the law did not allow unrestricted sales of weapons like the AR-15. That gun, they said, was “conceived out of the exigencies of modern conflict as trench warfare gave way to close-range, highly mobile combat.”

The shooter in the Dec. 14, 2012, attack was 20-year-old Adam Lanza, who began his rampage by murdering his mother in their home and ended it by turning his weapon on himself as he heard police sirens approaching.

After the shooting, Connecticut’s Democratic Gov. Dannel Malloy pushed through one of the strictest gun laws in the United States, banning more than 100 types of military-style rifles and limiting ammunition magazines to 10 bullets.

Modified versions of the AR-15 remain legal in Connecticut.

Even as Connecticut and neighboring states tightened their rules, other states rejected new curbs on gun ownership.