BOULDER, Colo. (AP) — The Colorado affiliate of the National Rifle Association has filed a lawsuit against the city of Boulder in an effort to pushback 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 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.

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Information from: Daily Camera, http://www.dailycamera.com/