PLEASANT HILL -- The National Shooting Sports Foundation has sued the city, alleging that an ordinance regulating firearms and ammunition sales was improperly approved, duplicates or conflicts with existing law and violates the Constitution.

Approved on Nov. 18, the ordinance requires a police permit for gun dealers. The law also prohibits gun stores from locating within 150 feet of a residence; within 500 feet of a park, another gun dealer, a massage parlor or an adult entertainment venue; or within 1,000 feet of a day care or school. Existing firearms dealers are exempt from the new location restrictions, but they must submit employees' background information to the Pleasant Hill police.

In a lawsuit filed Monday in Contra Costa Superior Court, the foundation, a gun industry trade group, alleges the distance requirements effectively make the law a zoning ordinance. As such, the group claims, the Planning Commission should have reviewed the measure before the City Council approved it. The suit seeks to overturn the ordinance. The lawsuit -- filed with City Arms East, one of four gun dealers in Pleasant Hill -- also claims that by giving the city the right to inspect gun stores without a search warrant the ordinance violates the Fourth Amendment protection against unreasonable searches and seizures. The lawsuit further alleges that the ordinance conflicts with state gun and labor laws, and that it requires insurance against liability for criminal conduct, which the National Shooting Sports Foundation claims is either impossible to insure or for which gun dealers have statutory immunity.

Pleasant Hill's ordinance won't enhance public safety and unfairly burdens gun dealers, who already must comply with numerous state and federal regulations, said Michael Bazinet, foundation spokesman.

"We again have a set of additional regulations being put upon law abiding retail establishments and customers," Bazinet said. "It's time to draw a line."

The National Shooting Sports Foundation also recently filed a lawsuit challenging Sunnyvale's gun control ordinance.

City Attorney Janet Coleson declined to comment on the lawsuit Monday, because she is still reviewing it. However, she has said the city followed the correct process in bringing the ordinance directly before the City Council because the measure did not revise the zoning code.

Pleasant Hill's firearms ordinance also requires that store owners and employees pass a criminal-background check. Dealers must install an alarm system and surveillance cameras and submit an annual report to the police chief detailing compliance with the regulations. The sole dealer in the city with a home occupancy permit to sell guns from his residence can continue operating, but no new permits for residential sales will be granted.

The courts have ruled that the Second Amendment doesn't prohibit government regulation of firearms dealers. Since the 1990s, gun control advocates have pressed city governments to adopt stronger regulations for firearms and ammunition dealers. At least 32 California counties and cities -- including Richmond, Antioch and Lafayette -- require a police permit or land use permit, according to the Law Center to Prevent Gun Violence, a national advocacy group.

Lisa P. White covers Martinez and Pleasant Hill. Contact her at 925-943-8011. Follow her at Twitter.com/lisa_p_white.