In a ruling issued Tuesday, U.S. District Court Judge Martin J. Jenkins cleared the way for a new First Amendment challenge to the 1999 ordinance.
County attorneys had asked the judge to dismiss the challenge, arguing that the gun ban is a public safety issue rather than a constitutional one, but Jenkins said the plaintiffs had sufficient grounds to continue with their lawsuit.
"Plaintiffs have articulated a particularized political statement that they intend to convey through possessing guns at gun shows," Jenkins wrote in denying the county's request for dismissal. "Plaintiffs have sufficiently alleged that their conduct ... constitutes speech."
The legal challenge is the latest in long-standing attempts to overturn the county's ban.
The main plaintiffs in the case are gun show owners Russell and Sallie Nordyke of Willows, who promoted gun shows at the Alameda County Fairgrounds in Pleasanton from 1991 to 1999, when the county adopted an ordinance making illegal the possession of firearms on county property.
The ordinance came in response to a 1998 fairgrounds shooting in which eight people were wounded.
The 9th U.S. Circuit Court of Appeals in San Francisco had earlier sided with the county and rejected show promoters' arguments
The plaintiffs appealed the ruling to the U.S. Supreme Court, which declined to take the case last October.
The Nordykes' attorney, DonaldKilmer of San Jose, said they retooled their complaint. Specifically, Kilmer argued that possessing guns at gun shows expresses a "firmly held belief" in the Second Amendment right to keep and bear arms and conveys support for the National Rifle Association's interpretation of the Second Amendment.
In a statement, Kilmer said the judge agreed that having guns at gun shows can be constitutionally protected "expressive conduct" a form of free speech.
"Gun shows are cultural events and are protected by the First Amendment and the California Constitution's Freedom of Expression clause," Kilmer said in the statement.
Kilmer also argued that possessing guns at gun shows conveyed solidarity with "gun culture" as well as patriotic and political messages, but the judge shot down those arguments, writing they are "inadequate to establish that gun possession amounts to speech."
County Counsel Richard Winnie did not return calls for comment Friday afternoon. In earlier interviews, he has said the ordinance does not infringe on First or Second Amendment rights.
"This is a simple case about the right of the public to protect public space," Winnie said in a 2004 interview.
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