From National Review:

In 2005, a wave of lawsuits threatened to bankrupt the gun industry. These suits were based on — pick your adjective — “creative,” “novel,” “inventive,” and “imaginative” legal theories that rarely held up in court, and they did their damage primarily by forcing gun companies to incur the costs of defending against them. Congress, seeing the problem, stepped in to put a stop to it — or at least tried to — by passing the Protection of Lawful Commerce in Arms Act (PLCAA).
A decade and a half later, anti-gun activists have responded with yet more new legal theories, and the Connecticut courts have bought one of them. Some families victimized by the Newtown massacre are being allowed to pursue a wrongful-death claim against Remington, which owns Bushmaster, the company that made the rifle used in the attack.