March 14 (UPI) -- In a victory for gun control advocates, the Connecticut Supreme Court overturned part of a lower court ruling Thursday to allow victims of the Sandy Hook shooting to sue gun manufacturer Remington.

The court voted 4-3 to remand the case to the Bridgeport Superior Court so plaintiffs can argue Remington violated the Connecticut Unfair Trade Practices Act by marketing a military-based weapon, the AR-15, to civilians.

Shooter Adam Lanza used a Bushmaster AR-15 in the Dec. 14, 2012, attack that killed 26 people, including 20 first graders, at Sandy Hook Elementary in Newtown. The AR-15 is a modified version of the military M-16 rifle.

"The families are grateful that our state's Supreme Court has rejected the gun industry's bid for complete immunity, not only from the consequences of their reckless conduct but also from the truth-seeking discovery process," plaintiffs attorney Josh Koskoff said in a statement. "The families' goal has always been to shed light on Remington's calculated and profit-driven strategy to expand the AR-15 market and court high-risk users, all at the expense of Americans' safety."

The high court dismissed most of the lawsuit's claims, but allowed the families' accusation related to marketing to proceed.

The decision opens the door for families to subpoena internal documents on how gun companies market the AR-15. The plaintiffs said Remington's model is too dangerous for the public and shouldn't be glorified to young people.

"The regulation of advertising that threatens the public's health, safety, and morals has long been considered a core exercise of the states' police powers," Justice Richard Palmer wrote for the majority.

The lawsuit was originally filed in 2015 by nine families and a teacher who was injured in the attack and also names as defendants distributor Camfour Holding and Riverview Gun Sales, where Lanza's mother Nancy purchased the gun as a gift for her son's 18th birthday. He fatally shot her with the gun before beginning the attack at the school. He killed himself before police could apprehend him.