The US Supreme Court dealt a blow to the firearms industry, rejecting Remington Arms Co's bid to escape a lawsuit by families of victims aiming to hold the gun maker liable for its marketing of the assault-style rifle used in the 2012 Sandy Hook school massacre that killed 20 children and six adults.

Key points: Families of Sandy Hook massacre victims filed a lawsuit against the arms manufacturer in 2014

Families of Sandy Hook massacre victims filed a lawsuit against the arms manufacturer in 2014 They argued the gun used in the attack, a semi-automatic civilian version of the US military's M-16, had been illegally marketed

They argued the gun used in the attack, a semi-automatic civilian version of the US military's M-16, had been illegally marketed Remington Arms argued that it should be protected by a 2005 federal law aimed at blocking a wave of lawsuits damaging to the firearms industry

The justices turned away Remington's appeal of a ruling by Connecticut's top court to let the lawsuit proceed despite a federal law that broadly shielded firearms manufacturers from liability when their weapons were used in crimes.

The lawsuit will move forward at a time of high passions in the US over the issue of gun control.

The family members of nine people slain and one survivor of the Sandy Hook massacre filed the lawsuit in 2014.

Remington was backed in the case by a number of gun rights groups and lobbying organizations, including the powerful National Rifle Association (NRA), which is closely aligned with Republicans including President Donald Trump.

The NRA called the lawsuit "company-killing".

Detective Barbara Mattson, holding the same make and model of the rifle used by the shooter, in a court hearing in 2013. ( AP: Jessica Hill )

The 2012 rampage was carried out by a 20-year-old gunman named Adam Lanza, who shot his way into the Sandy Hook Elementary School in Newtown, Connecticut and fired on first-graders and adult staff before fatally shooting himself as police closed in.

The US has experienced a succession of mass shootings in recent decades, including the 2017 attack at a Las Vegas concert that killed 58 and one at a nightclub in Orlando in 2016 that killed 49.

Assault-type rifles have been a recurring feature in many of the massacres.

The US Congress has not enacted new gun control laws in the wake of the mass shootings largely because of Republican opposition.

Remington's legal team says the company should be shielded by the Protection of Lawful Commerce in Arms Act. ( Reuters: Lucas Jackson )

The plaintiffs have argued that Remington bears some of the blame for the Sandy Hook tragedy.

They said the Bushmaster AR-15 gun that Lanza used — a semi-automatic civilian version of the US military's M-16 — had been illegally marketed by the company to civilians as a combat weapon for waging war and killing human beings.

The plaintiffs said that Connecticut's consumer protection law forbade advertising that promoted violent, criminal behaviour, and yet even though these rifles had become the "weapon of choice for mass shooters" Remington's advertisements "continued to exploit the fantasy of an all-conquering lone gunman".

One of them, they noted, stated: "Forces of opposition, bow down."

Josh Koskoff, a lawyer for the plaintiffs, said the families were grateful that the court denied Remington's appeal.

"We are ready to resume discovery and proceed toward trial in order to shed light on Remington's profit-driven strategy to expand the AR-15 market and court high-risk users at the expense of Americans' safety," he said in a statement.

A Remington representative could not be reached for comment.

The NRA said the lawsuit against Remington was "company-killing". ( Reuters: Adrees Latif )

The company argued that it should be insulated from the lawsuit by a 2005 federal law known as the Protection of Lawful Commerce in Arms Act, which was aimed at blocking a wave of lawsuits damaging to the firearms industry.

The case hinges on an exception to this shield for claims in which a gun manufacturer knowingly violates the law to sell or market guns.

Remington has argued that the Connecticut Supreme Court interpreted the exception too broadly when it decided to let the case go ahead.

Though the case does not directly implicate the US Constitution's Second Amendment right to keep and bear arms, the NRA told the justices in a filing that the lawsuit could put gun manufacturers out of business, making the right meaningless.

A state trial court initially threw out the claims but the Connecticut Supreme Court revived the lawsuit in March, prompting Remington's appeal.

The justices already have taken up one important gun rights case in their current term.

They are due to hear arguments on December 2 in a lawsuit by gun owners and the state's NRA affiliate challenging New York City restrictions on handgun owners transporting firearms outside the home.

Reuters