Sandy Hook families argue the rifle used in the 2012 school massacre should not have been entrusted to civilians.
The defense tried to block the case on the basis of a federal law that shields gun companies from legal action.
The families argue that the sale of the military-style rifle used in the 2012 massacre violated Connecticut's law.
A gun-violence victim's family is alleging that retailers knew guns were being sold to a "straw purchaser."
A lawyer for the gun maker argued Monday that it's not the role of a court or jury to decide who can own AR-15 rifles.
Sandy Hook families continue to argue the AR-15 rifle is too dangerous to entrust to the public.
A judge has denied a motion to dismiss a lawsuit brought by families affected by the Sandy Hook Elementary School shooting.
New York has some of the toughest gun laws in the country.
Mark and Jackie Barden are among 10 families suing gun companies for the weapon used in the Sandy Hook massacre.
Gun distributors currently are protected under a 2005 law that grants them immunity from civil lawsuits brought by victims of violence.
Some Democrats fear Hillary Clinton's recent attacks on Bernie Sanders's gun record and health care policy could hurt their party.
The Democratic presidential front-runner urged Americans not to give up hope that the gun lobby can be defeated.