The Sandy Hook families won a victory in the state Supreme Court that gives them a day in trial court, perhaps. But the barriers to an ultimate win over Remington, the historic gunmaker, are steep and many, with legal and financial issues as a roadblock.

The Supreme Court’s narrow, 4-3 ruling Thursday said the case against Remington over the 2012 shooting at Sandy Hook can go to a trial in state court. It establishes legal precedent for both the federal law that protects firearms makers from liability and the Connecticut Unfair Trade Practices Act that dates back to 1973.

And it puts the victims’ families in a position where they may be able to try to prove a connection between Remington’s marketing for its Bushmaster AR-15 rifle and the horrific act of violence by a disturbed 20-year-old. The state Supreme Court said they can try; making the connection, lawyers and experts say, is a steep challenge.

“It is a Herculean task,” said Victor E. Schwartz, co-chairman of the public policy practice in the Washington, D.C., office of the law firm Shook, Hardy & Bacon — quoting from the Supreme Court’s majority opinion.

Schwartz, co-author of the best-selling textbook on tort law, in print since 1976, said, “There is absolutely not a scintilla of evidence that would show if the actions taken by the wrongdoer were influenced by the advertising.”

The Supreme Court decision didn’t rule on whether such evidence exists; only that the families, under state and federal laws, have a right to try to show it.

“When the plaintiffs’ lawyer was asked about that, he dodged it,” Schwartz said. “How are they going to show that this advertisement caused a third party to do this violent act?”

The decision establishes, for the first time, that plaintiffs can get around the 2005 federal law giving protection to gunmakers from liability even though there was no finding of “negligent entrustment” — basically, when a purveyor irresponsibly sells or gives something to someone who then causes harm, such as a bartender serving a drunk person who then drives.

And in Connecticut, the decision significantly expands the Connecticut Unfair Trade Practices Act. For the first time, the court has allowed the act to be used in cases where there was no “commercial relationship.” The shooter did not buy the gun he used to kill 20 first-graders and six educators at the Sandy Hook Elementary School; his mother did.

“The court abandoned, or said it never really had, a commercial relationship test,” said Robert M. Langer, a partner and head of the antitrust and consumer protection practice at Wiggin & Dana in Hartford.

“There are a number of cases ... that have concluded over the past 15 years that a private litigant needed to have that type of commercial relationship,” Langer said. “It has been uniformly applied up until now.”

He added, “If I were on the Connecticut Supreme Court, I would have ruled differently.”

That provision is not subject to reversal by the U.S. Supreme Court, in the event a Remington appeal were to be accepted by the high court.

Speaking on Thursday, a partner with Koskoff, Koskoff & Bieder called the Connecticut court decision “a turning point” in the legal quest of 10 families the firm represents in holding Remington accountable for selling the gun used in the murders.

“The court has said … that the gun industry — in this case Remington — is protected in many, many ways that other industries (are not), and they have not agreed with many of our claims based on that immunity,” said Josh Koskoff, the partner who is leading the firm’s work on the case. “But they’ve approved of this fundamental principle that you cannot as an industry — or as a company that is engaged in the sale and marketing of dangerous items — you can’t engage in reckless marketing that does nothing to address a problem, but only contributes to it.”

Again, though, the key is in the connection between the marketing and the murders.

Remington Outdoor Co., which owns Bushmaster, was recently in bankruptcy. The company, with its roots in Bridgeport, has its headquarters gun manufacturing plant in Madison, N.C., with a larger factory at another historic base in Ilion, N.Y.

A year ago, with obligations of more than $1 billion under former owner Cerberus Capital, Remington undertook a swift bankruptcy reorganization under Chapter 11 protections that shifted control of the company to creditors JPMorgan Chase and Franklin Advisors.

At the time of the bankruptcy filing, Remington indicated it expected claims to be filed on behalf of litigants through several law firms, including Koskoff, Koskoff & Bieder, without specifying amounts those plaintiffs might seek.

“Remington has tried everything during this five-year period to prevent us from looking at their stuff,” Koskoff said Thursday. “At the end of the day, you just have to wonder what are they hiding? Why don’t they just turn it over? If they are so confident that we don’t have a case, let’s see your stuff.”

As of last May, Remington listed assets of $841 million, more than a quarter of that amount represented by the estimated value of the company’s existing inventory of weapons and parts that anti-gun activists would rather keep off the street.

Remington reported sales of $43.4 million for a period of just over a month through early May, and a net cash outflow of $27.1 million when factoring in disbursements totaling $70.5 million.

Remington has not published updated finances since. Multiple media outlets reported the company initiated layoffs this month that could total 200 jobs.

Rep. Steve Stafstrom, D-Bridgeport, a lawyer and co-chairman of the legislative Judiciary Committee, said he is eager to see what the Sandy Hook families can find out during the discovery process.

“Frankly, I’m happy to see the Supreme Court allow them their day in court to present their argument to a jury. I think we’re going to see some very interesting things come out during discovery, and the bottom line is that no one needs an AR-15 assault rifle. And the allegation that that rifle is being marketed for children should be very concerning to every resident.”

Schwartz, the Washington lawyer and tort expert, said, “as the great Justice Benjamin Cardozo once keenly observed, ‘negligence in the air will not do.’ You need causation.”

Connecticut Media Group