The Connecticut high court disagreed.
The plaintiffs argue that the gun-maker "attract [ed] buyers by extolling the militaristic and assaultive qualities of their AR-15 rifles" by "advertising that the most elite branches of the military - including Special Forces, SEALs, Green Berets, and Army Rangers - have used them". According to the lawsuit, the business of selling "modern sporting rifles" to the general public is one giant tort, even though these guns are very rarely used to commit crimes.
"The regulation of advertising that threatens the public's health, safety, and morals has always been considered a core exercise of the states' police powers", Justice Richard Palmer wrote for the majority.
In 2016, a lower-court judge dismissed the case in response to a request by Remington, citing a federal statute that protects gun manufacturers and distributors from being implicated if their weapons are used in criminal activity.
Nine of the families originally filed the lawsuit in 2014, and have faced delays as the case was sent from federal to state-level courts and as Remington filed for bankruptcy past year.
The court's narrow decision, overturning a lower court judge, rules that Remington can be sued over its marketing practices under a ct state law, despite protections offered to gun manufacturers by federal law. The case was ordered back to a trial court, where a survivor and the families of nine victims will be able to bring their argument in front of a jury.
Instead, it would depend on the justices' interpretation of the broader legal question of whether federal courts should generally be allowed to interfere in state law, experts said.
Remington attorneys previously argued that the Protection of Lawful Commerce in Arms Act protects companies involved in the sale of the gun that ended up in Lanza's hands from this exact kind of lawsuit.
"Today's decision is a critical step toward achieving that goal", he added.
Joshua Koskoff, a lawyer for the plaintiffs, has said the Bushmaster rifle and other AR-15-style rifles were designed as military killing machines and should never have been sold to the public.
The lawsuit seeks undisclosed damages.
The case had been closely watched by advocates on both sides of the gun issue.
Because this decision involves interpretation of a federal statute, the gunmaker will nearly certainly appeal it to the U.S. Supreme Court, and Remington could also prevail at a trial, so this is just a first step toward manufacturer liability. The lawsuit will now allow the plaintiffs to gain access to internal Remington documents that can shed light on its advertising practices.
Remington, based in Madison, North Carolina, filed for bankruptcy reorganization last year amid years of slumping sales and legal and financial pressure over the Sandy Hook school massacre.