BOULDER – The Colorado affiliate of the National Rifle Association has filed a lawsuit against the city of Boulder in an effort to push back against the city’s new assault-weapon ban.

Lawyers for the Colorado State Shooting Association, Boulder-based Gunsport of Colorado and two private citizens say the new ordinance, which took effect Friday, is invalid because sections of it conflict with state law.

The Daily Camera reports the lawsuit specifically cites the ordinance’s requirement that owners of banned weapons receive a certificate from the city proving ownership, the prohibition of the sale and possession of weapons by people under 21 and the prohibition on the open carry of rifles and shotguns.

A Boulder spokesman didn’t immediately respond to a request for comment.

The complaint follows another lawsuit filed last month by Jon Caldara of Boulder – a broadcast host and president of the Independence Institute, a libertarian think tank – as well as the Boulder Rifle Club, also challenging Boulder’s gun ordinance. Attorneys from the conservative Mountain States Legal Foundation are representing those plaintiffs.

The ban – city Ordinance 8245 – was passed unanimously by the Boulder City Council. It bans sale and possession of guns the city defines as assault weapons along with bump stocks (a.k.a. “multi-burst trigger activators”) devices that allow a gun to be fired rapidly) and large magazines.