The U.S. Supreme Court declined to review the ruling, without comment from any individual justice.
The lawsuit was brought by the estates of nine victims killed by Adam Lanza, who was armed with the high-powered rifle, made by Remington Arms Co., during his assault that left 28 dead, including 20 young children.
Gun-control advocates applauded the Supreme Court’s decision not to block the lawsuit.
“Gun manufacturers throughout the country should be on notice that they’ll need to answer for their reckless business practices in the courts,” Eric Tirschwell, managing director of litigation for Everytown Law, said in a statement.
“This reaffirms that the gun industry is not above the law and that the families of the Sandy Hook victims will have their day in court,” he said.
The Connecticut court’s 4-to-3 decision in March overcame a federal law backed by the National Rifle Association and designed to immunize gunmakers from liability for the crimes committed with their weapons.
The narrow state court decision limited liability for gunmakers based on how they advertise their firearms, rather than on the sale to third parties who go on to commit crimes. In its ruling, the court said companies that market military-style guns to civilians as a way of killing enemies could be violating state fair-trade laws.
Even so, the decision was seen as having broad implications for gun-control advocates across the country who have had little success in seeking ways to hold gunmakers responsible for crimes committed with their products.
Remington had convinced a lower court that federal law prevented the families’ lawsuit. But Connecticut’s high court said that the law had exceptions and that one of them was meant for state consumer protection laws.
The NRA fought hard to get the immunity from Congress, saying it was needed to protect U.S. companies from costly, and what it sees as unfair, litigation that blames the corporations for the crimes of others.
“Lawsuits that deflect attention away from mental illness and criminals in order to blame inanimate objects won’t reduce violent crime or make anyone safer,” Jason Ouimet, executive director of the National Rifle Association Institute for Legislative Action, said in a statement Tuesday.
“The firearm on which citizens and first responders rely isn’t the actual problem; the sociopath who steals and misuses a firearm against innocent people is the real problem,” he said.
Remington declined to comment.
Connecticut lawmakers in Washington called the state Supreme Court’s order a “crack in the legal armor of the gun industry” and said it reinforces the need for Congress to pass legislation repealing the immunity measure.
“For years, gun manufacturers have been allowed to operate with near-blanket immunity — producing weapons of war and marketing them to the masses with zero accountability,” Democratic Sens. Richard Blumenthal and Chris Murphy, and Rep. Jahana Hayes, all of Connecticut, said in a statement.