Sandy Hook

The gun-maker had appealed to the highest federal court after the Connecticut Supreme Court allowed the lawsuit over the 2012 school massacre in Newtown, Conn., to go forward in March.

Fears of inspiring copycats and a recent surge in "morbid fascination" visitors have prompted school officials to consider tearing down the building. The school's name and mascot would stay the same.

Gun companies have rarely been held liable for crimes committed with their products. This lawsuit could mark a new front in the battle over gun regulations and corporate accountability.