O'Brien added that "the attempt here is not only to blur, but ob literate, the line that separates public nuisance claims from those based on product liability law."

Courts in some states, including Illinois and Massachusetts, have allowed such suits to proceed, the judge wrote. In Missouri, gun regulation in manufacturing and sale is reserved by statute to the Legislature, O'Brien said.

Efforts Tuesday to reach city officials were unsuccessful. The city could appeal O'Brien's ruling.