The high court decided it won't take up the case, but said the families can still seek damages from the gun company over the 2012 Newtown, Conn., attack that killed 20 children and six adults. Justices rejected Remington's argument that firearm manufacturers are shielded from liability in crimes.
The families argue Remington marketed the AR-15-style assault rifle in a fashion that inspired shooter Adam Lanza to plot the attack. Advertisements, they say, promoted the gun as "a highly lethal weapon designed for purposes that are illegal -- namely, killing other human beings."
The lawsuit says Remington should never have sold a weapon that dangerous to the public -- and argues Remington used product placement in violent video games.
Remington has argued a 2005 federal law shields gunmakers from liability for crimes committed with their products. Tuesday, the Supreme Court justices rejected that position.
On the day of the attack, Lanza took the weapon -- which was legally owned by his mother -- from his home and began shooting at the school. He killed his mother before leaving for the school.
Tuesday's decision lets stand a Connecticut Supreme Court ruling earlier this year, which said family members are "entitled to have their opportunity to prove their wrongful marketing allegations."
The high court decision also opens the door for other victims of gun crimes to file suit against gunmakers.