(CNN) To hear Jackie Barden and David Wheeler describe their lives today is a master class in hope.

On December 14, 2012, Barden's youngest son, 7-year-old Daniel, and Wheeler's son, 6-year-old Ben, were among those killed at Sandy Hook Elementary School in Newtown, Connecticut.

"(My husband) Mark and I still have a great life, and we really have to remember that," Barden said, adding that their two children bring the family an enormous amount of love and strength. "We are fortunate with what we have with the two of them."

"I am a completely different person," she said, referring to the life she leads since her son was killed.

Wheeler said his life has changed in every way.

"It's not as though there aren't moments of hope and beauty in every second of every day, because there are," he said. "The trick is finding them ... when you don't feel like you can."

What gets him out of bed, he said, is the challenge of making sure no more parents or families have to endure what they did: 20 children and six educators killed when a young man unloaded 154 rounds from an AR-15 semiautomatic rifle.

That rifle is based on an automatic, lightweight weapon originally commissioned by the U.S. military. The only limit to the speed the AR-15 fires is how fast a shooter can pull the trigger for each round.

"Each of the kids had three to eight bullets in them," Barden said. "There is just something wrong if that can happen."

Wheeler and Barden are part of a potentially precedent-setting lawsuit seeking accountability from gunmaker Remington

"Our families deserve that day in court," said Joshua Koskoff, an attorney representing nine victims' families and a teacher who survived. "We believe they should be accountable to their fair share of responsibility."

The case has the potential to make history if it goes to trial. A 2005 federal law, the 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 -- in this case the AR-15 rifle.

"It's always been a big uphill battle for plaintiffs to sue the gun industry," said Georgia State University law professor Timothy Lytton. "It was even before the immunity (legislation), and it's an even bigger one now."

One exception to the immunity legislation is what's called "negligent entrustment."

"Say a gun retailer handed a gun to a visibly intoxicated person, then they're not subject to the immunity," said Lytton, who studies gun industry litigation.

You might ask: Since Remington did not come into direct contact with the shooter -- that happened at a gun retailer -- how would that apply? The lawsuit argues that the way in which the company sells and markets a military-style weapon to the civilian market is a form of negligent entrustment.

"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 tremendous amount of diligence, in terms of training, storage, who gets the weapon, and who can use it," Koskoff, the attorney for the families, said. "They took that same weapon and started peddling it to the civilian market for the purposes of making a lot of money."

Remington declined to comment, but in its request to dismiss the suit, the company argued that the 2005 legislation provides it "complete immunity."

The families of people who died at Sandy Hook Elementary School disagree.

"You have to face the consequences for your specific actions," Wheeler said. "Good companies don't need bad legislation to protect them."

Barden said she has a hard time explaining to her two children why the AR-15 was introduced to the civilian market or why manufacturers have targeted teenage boys in video games like "Call of Duty," which features AR-15-style Remington rifles.

"It's hard to explain when you really don't know why yourself," Barden said. "It's hard to answer because you know you don't want them growing up being afraid."

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Barden would love to see the AR-15 off the market, but she realizes the reality they're up against.

Remington has filed a motion to dismiss the lawsuit, citing the 2005 law. A state court judge in Bridgeport, Connecticut, will hear from both sides Monday afternoon. If the judge rules in favor of the families, the case would move to a discovery, or fact-finding, phase, and one step closer to a possible trial.

Barden and Wheeler said they might always have a "huge, heavy curtain" hanging over them, but that even if this case doesn't make it to trial, they've already won something.

"If it all stops at this point, we have moved the conversation this far," Wheeler said. "And I think that is incredibly important, I really do."