(Adds comment from plaintiffs' lawyer, other retailers)
By Jonathan Stempel
NEW YORK, June 22 (Reuters) - A federal appeals court on Friday upheld the constitutionality of New York state's ban on gravity knives, which can be opened to a locked position with a one-handed flick of the wrist.
By a 3-0 vote, the 2nd U.S. Circuit Court of Appeals rejected claims by three Manhattan plaintiffs that the ban was vague and could trap unsuspecting people who want to buy, sell or own common folding knives.
The decision is a defeat for the artist John Copeland and art dealer Pedro Perez, both arrested for violating the ban, and Native Leather Ltd, a Greenwich Village retailer that agreed to test its knives and submit to inspections to avoid prosecution.
They said the ban made it impossible for people to know which knives were legal, including for use in their jobs.
"We are, naturally, disappointed with the decision, and we are reviewing our options," Daniel Schmutter, a lawyer for the plaintiffs, said in an email.
The office of Manhattan District Attorney Cyrus Vance defended the ban and welcomed the decision.
"Gravity knives are dangerous weapons which do not belong on city streets and subways," spokesman Danny Frost said in an email.
Seven retailers, including Native Leather, Home Depot Inc and Paragon Sports entered deferred prosecution agreements with Vance in June 2010 over sales of illegal knives.
New York bans several relatively obscure items as weapons, including cane swords, chuka sticks and plastic knuckles.
Chief Judge Robert Katzmann said the plaintiffs did not show that the ban on gravity knives was invalid on its face, citing Native Leather's failure to show it "lacked sufficient notice or the opportunity to understand" that it sold them.
He also said the plaintiffs did not explain why people would lack notice that some common folding knives with loose-fitting blades and a "very light bias toward closure" might be illegal.
Katzmann nonetheless said New York Governor Andrew Cuomo and the state legislature might "give further attention" to the ban.
"The statute's reliance on a functional test and imposition of strict liability on what can be a common, if dangerous, household tool might in some instances trap the innocent by not providing fair warning," he wrote. "The sheer number of people who carry folding knives that might or might not respond to the wrist-flick test raises concern about selective enforcement."
Friday's decision upheld a January 2017 ruling by U.S. District Judge Katherine Forrest in Manhattan after a non-jury trial.
The case is Copeland et al v Vance, 2nd U.S. Circuit Court of Appeals, No. 17-474. (Reporting by Jonathan Stempel in New York; Editing by Bernadette Baum)