With that type of marketing, the Sandy Hook families claim, “The Bushmaster Defendants attract buyers by extolling the militaristic and assaultive qualities of their AR-15 rifles.” The complaint alleges that while the weapon is suitable for the military and for law enforcement—where it’s used for combat and limited police purposes—in civilian hands, the high-caliber, rapid-fire rifles are essentially killing machines.

One law professor sees those claims as having some chance of success—if not in court then at least in shaping public opinion. John Culhane of Widener University’s Delaware Law School, a longtime advocate for using litigation to reform gun-industry practices, says the plaintiffs deserve points for creativity by trying to find a way around PLCAA through an attack on the industry’s selling of tactical firearms to civilians.

“It’s a long shot,” Culhane concedes, but the plaintiffs’ argument holds powerful potential if the suit manages to reveal the thinking behind the riflemaker’s marketing strategy for the military-grade firearms. Positioning the case as a contest between commercial exploitation and parents mourning murdered children puts enormous pressure on the industry, he says.

That pressure might be compounded by the enormous expansion of the tactical weapons and accessories market, which industry watchers believe is a chief engine of growth in the gun business. That’s largely due to the success of the AR-15, the semi-automatic civilian version of the U.S. military’s automatic M-16 rifle. The weapon is designed for endless tinkering, and has proven especially popular with young buyers more attuned to owning guns as a social pursuit, in contrast with more traditional markets in hunting and self-defense.

But the marketing-to-civilians argument can cut both ways. As Frank Miniter pointed out in the National Rifle Association magazine America’s 1st Freedom, the millions of civilian sales of AR-15s are evidence that the so-called “black rifle” has been embraced by the general public mainly without incident, a fact that would seem to undercut the Newtown plaintiff’s claim that the AR-15’s true utility is confined to criminal mayhem.

The Newtown lawsuit’s tug-of-war serves as a kind of replay of the debate that led to Congress’ passage of PLCAA in the first place.

Congress was prompted to pass the law by industry complaints that the firearms business might be sued out of existence by innovative legal attacks, brought at the time mostly by cities seeking to hold manufacturers or retailers liable for the costs of gun violence. PLCAA was meant to shut down those sorts of claims, which branded guns as a public nuisance under tort law, while preserving more traditional liability claims, says Georgia State law professor Timothy Lytton, who studies gun litigation.