The Supreme Court refused Tuesday to shield a major arms manufacturer from potential liability in the 2012 school shooting that left 26 students and educators dead in Newtown, Conn.

The justices’ action allows a lawsuit filed by parents of Sandy Hook Elementary School victims to move forward at the state level, on the allegation that Remington Arms Co. marketed the military-style rifle used in the mass shooting “for use in assaults against human beings.”

The case tests the reach of a 2005 law passed by Congress to protect firearms manufacturers from being held liable for crimes committed by gun purchasers. That law was hailed by the National Rifle Association, but it included exceptions, including one for violating rules related to marketing and advertising.

Gun control advocates have said a victory by the families in the long-running dispute could lead to more lawsuits and damaging disclosures involving the firearms industry.