The families of victims massacred by a gunman at 101 California St. in 1993 asked a California appeal court on Thursday to do what no U.S. appellate court has ever done: hold a gun manufacturer liable for manufacturing a deadly assault weapon.

With a handful of victims’ relatives in attendance, a First District Court of Appeal panel gave the plaintiffs’ attorney ample time to make his case in 21/2 hours of oral argument in Merrill v. Navegar, A079863.