At issue are what the families allege are the manufacturer's marketing strategies and other trade secrets on military-style weapons.
Some experts believe the discovery process could yield the type of incriminating internal information unearthed during landmark litigation against tobacco companies in the 1990s.
"A successful suit that would have a similar level of discovery in this kind of litigation would be ... of historic proportions," said Dr. Richard Hurt, a Mayo Clinic internal medicine specialist who was a key witness in a 1994 Minnesota suit against the tobacco industry
"The gun manufacturers know more about their product than anybody else on the planet."
Like gun manufacturers today, the tobacco industry was once legally impregnable. In the case of the gun industry, that's because a federal law gives gun businesses general protections from civil lawsuits.
The Sandy Hook families
hope to shatter that armor with allegations that the gun maker deliberately marketed a risky military-style weapon to civilians, specifically young men.
What's the Sandy Hook lawsuit about?
The families are suing the Remington Arms Co., manufacturer of the type of gun used in the shooting that killed 20 children and six educators at Sandy Hook Elementary School on December 14, 2012.
In addition to monetary and punitive damages, the plaintiffs want the Bushmaster AR-15 -- the type of semiautomatic rifle used in the attack -- removed from the civilian market.
Citing a string of mass shootings involving semiautomatic rifles, the Sandy Hook families argue that the "AR-15 is the weapon of choice for shooters looking to inflict maximum casualties, and American schools are on the forefront of such violence," according to court documents
The suit claims the gun manufacturer was reckless in selling a weapon "with no conceivable use ... other than the mass killing of other human beings" and "unscrupulously marketed and promoted the assaultive qualities and military uses of AR-15s to a demographic of young civilians."
The suit was filed last year by nine of the 26 victims' families and Natalie Hammond, a vice principal who was shot and survived. They are demanding that Bushmaster and its owner, Remington, turn over documents about firearm safety and sales practices.
The troubled 20-year-old Lanza embarked on his killing spree with a Bushmaster AR-15 rifle and 10 30-round magazines. His mother, Nancy, had legally purchased the weapon. She was shot and killed at home by Lanza before the school slaughter.
In less than five minutes, Lanza unloaded 154 rounds at Sandy Hook, according to court documents.
"Each of the kids had three to eight bullets in them," said Jackie Barden, whose 7-year-old son, Daniel, was one of the children shot and killed at the school. "There is just something wrong if that can happen."
The semiautomatic rifle unleashes a barrage of bullets within seconds, without the need to reload often, according to the complaint. "The net effect is more wounds, of greater severity, in more victims, in less time," reads the complaint.
"Remington took a weapon that was made to the specs of the U.S. military for the purpose of killing enemy soldiers in combat -- and that weapon in the military is cared for with (a) tremendous amount of diligence, in terms of training, storage, who gets the weapon and who can use it," said attorney Josh Koskoff, a representative for the families of Sandy Hook victims. "They took that same weapon and started peddling it to the civilian market for the purposes of making a lot of money."
Remington has declined to comment to CNN on the pending litigation. However, in a court filing, an attorney for Remington blamed the massacre on the shooter: "Adam Lanza's criminal actions were the sole proximate cause of the deaths and injuries he inflicted."
Remington attorney Scott Harrington, in seeking dismissal of the lawsuit, argued that the 2005 Protection of Lawful Commerce in Arms Act grants gun manufacturers immunity from any lawsuit related to injuries that result from criminal misuse of their product.
Previous lawsuits against the gun industry
Lawsuits against gun makers were inspired by class-action lawsuits against manufacturers of products such as asbestos, Agent Orange, silicone breast implants and tobacco, according to Georgia State University law professor Timothy Lytton.
Injury victims, advocacy groups and attorneys began filing claims against product manufacturers in the 1960s in response to public health problems, said Lytton, an expert in gun cases. In the 1980s, claims against gun makers began to paint the violence as a public health issue.
"The value of gun litigation was that it reframed the issue ... from a problem of street crime or mass shootings to a problem of industry distribution and marketing practices," Lytton said.
Groups such as the National Shooting Sports Foundation
-- the firearms industry's trade association, based in Newtown -- have long maintained that the criminal misuse of guns is a criminal justice issue, not a public health one.
U.S. Surgeon General Vivek Murthy, however, has called gun violence a major public health issue. According to the FBI, rifles (including semi-automatics such as the AR-15), are linked to about 300 deaths in the U.S. each year, and the Centers for Disease Control and Prevention reported 33,636 overall firearms deaths in 2013.
Since the 1980s, gun victims and dozens of municipalities have filed claims against dealers and manufacturers, seeking to recover gun violence-related costs for law enforcement and emergency medical services.
In 2000, Smith & Wesson, the nation's leading gun manufacturer, agreed to what government officials called a "historic" legal settlement in which the company agreed to make several changes in its gun marketing, manufacturing and design practices. The settlement was widely criticized within the industry; the gun maker faced a boycott from gun buyers and took a major financial hit.
Last year, a civil court jury in Milwaukee awarded about $5 million in damages
after finding a gun shop negligent for illegally selling a pistol to a man who shot two police officers. The two sides later agreed on a $1 million settlement.
The suit was only the second of its kind to reach a jury since the 2005 Protection of Lawful Commerce in Arms Act
, according to experts.
Gun manufacturers' protection from liability
That act came in response to a spate of suits accusing manufacturers of not doing enough to ensure safe distribution of guns or prevent the flow of guns onto the black market. The rationale was that manufacturers and dealers who follow the law should not be held accountable for the actions of criminals.
The controversial 2005 law and gun control have been contentious topics in this year's Democratic presidential race, with Hillary Clinton attacking Bernie Sanders
for his Senate vote in favor of the law.
In March, during CNN's Democratic debate in Flint, Michigan, the candidates sparred over the Sandy Hook lawsuit.
Sanders said gun manufacturers are not legally liable.
"If they are selling a product to a person who buys it legally, what you're really talking about is ending gun manufacturing in America," he said. "I don't agree with that."
Clinton responded, "No other industry in America has absolute immunity."
In a statement, the National Shooting Sports Foundation called out Clinton, saying the law allows lawsuits for "knowing violations of federal or state law related to gun sales, or on traditional grounds, including negligent entrustment or breach of contract." The act also permits product liability cases involving injuries from defective firearms.
"Without the protection against junk lawsuits, such as the PLCAA provides to our industry members, many of America's most critical industries would go out of business from the time and costs of frivolous lawsuits," the statement said.
"Industries cannot and should not be held legally responsible for the wrong-doings of individuals who purchase their products legally and then proceed to use them illegally."
But Jon Vernick, co-director of the Johns Hopkins Center for Gun Policy and Research, said the law affords gun makers an almost exclusive degree of legal protection.
"Litigation has potential to serve more than one purpose: compensating victims but also a potential to serve a more societal purpose, a public health purpose to get information out and provide manufacturers with an incentive to either design or market their products more safely," he said.
The Protection of Lawful Commerce in Arms Act changes the playing field, Vernick said.
"The tobacco industry did not enjoy this kind of immunity from having a lawsuit even go forward. It's one thing to say that a case is hard to win, as the tobacco litigation was. It's another to say that it can't even be brought at all," he said.
Parallels between gun and tobacco litigation
The landmark 1998 Tobacco Master Settlement Agreement followed decades of failed litigation.
"If you sued them for $1 million, they were prepared to spend $20 million to defeat your million-dollar claim in order that the message would go out from coast to coast that there's no point in suing them," said Doug Blanke, founder and director of the Public Health Law Center at the Mitchell Hamline School of Law in Minnesota.
A group of 46 states reached an agreement with leading tobacco companies that called for manufacturers to pay the states $206 billion and submit to sweeping advertising and marketing restrictions.
Four other states -- Florida, Minnesota, Mississippi and Texas -- negotiated separate settlements with cigarette makers.
The cases represented the five largest settlements in the history of litigation.
Until the tobacco settlements, the cigarette was largely exempt from government regulation, Blanke said.
He and others pointed out how, since Sandy Hook, Congress has rejected additional money to fund research into gun violence. They see it as a sign of the strength of the gun lobby in the United States.
"Gun manufacturers stand in a position that has some similarity to where tobacco manufacturers used to be," said Blanke, who was involved in the tobacco litigation as an assistant attorney general in Minnesota.
"They've got enough influence that they've been able to create special rules just for themselves that give them a unique kind of immunity or shelter from the accountability.
"If facts were to come out, hypothetically, in which the gun companies were shown to have been as cynical and as manipulative and as intentional behind their closed doors as the cigarette manufacturers were, then in the long run, I think public attitudes will shift and society will insist that these companies play by the same rules as every other business," Blanke said.
The National Rifle Association, the nation's leading gun rights organization and a top lobbying group, did not respond to requests for comment.
How gun manufacturers are not like cigarette makers
Lawrence Keane, senior vice president and general counsel of the National Shooting Sports Foundation, dismissed the comparison to tobacco litigation as "an old and invalid analogy."
"Tobacco, when used as intended, causes harm to the user," he said via email. "Firearms, when used as intended, save lives. The lawful commerce in firearms is constitutionally protected. Tobacco is not."
Keane said the gun industry has survived years of "costly, vexatious litigation" filed by gun control attorneys and tobacco trial lawyers who modeled their suits on earlier legal strategies.
"In several cases ... these plaintiffs' lawyers took extensive discovery searching for those very internal documents of alleged 'industry secrets' about gun design and marketing," he said.
"They took dozens and dozens of depositions of all of the major manufacturers and received a warehouse full of documents. ... Not a single case was successful. So no, there is no comparison to the tobacco litigation."
In the Big Tobacco cases, settlements were reached during a decades-long national transformation toward lower tolerance for smoking, according to Lytton. That's not happening with gun control.
"You have people who are increasingly stuck in their positions who are basically suspicious of any additional controls on the sales of firearms, and you have people who are increasingly zealous about trying to shut down access to firearms," he said.
"I think there's a stalemate, and that stalemate is reflected in Congress."
Unlike smoking, the causes of gun violence and strategies to prevent it have not been extensively studied by public health authorities.
A 2015 CNN investigation showed that the nation's leading public health official, CDC Director Dr. Tom Frieden, had never -- during his six years on the job -- talked publicly about gun violence, which kills more people in the U.S. each year than AIDS, colon cancer or prostate cancer.
Frieden declined to comment for the report, but his defenders say he's being wise. They say that if he dares to publicly talk about lives lost to guns, Congress might retaliate by taking away CDC funding for a whole host of safety issues. That, they say, is the strength of the gun lobby.
As the case involving Sandy Hook victims and Remington moves forward, there is much at stake in one of the most divisive debates in the country.
"The Sandy Hook lawsuit -- win, lose or draw -- has drawn increasing attention to the gun industry's marketing, sales and distribution practices as part of the issue of gun violence," Lytton said.