Mayor Bloomberg’s anti-gun crusade suffered a defeat yesterday when a federal appellate court rebuffed his attempt to sue manufacturers of firearms.

The suit, which Mayor Giuliani initiated in 2000 and Mr. Bloomberg has pursued since taking office, claimed that manufacturers such as Beretta, Browning, Glock, and others were indirectly contributing to gun violence in New York City by not regulating how their products were sold. The city had sought a court order requiring the companies to take a variety of steps to monitor gun shows and discourage the sale of more than a single gun at a time to a purchaser. The city claimed that by not policing how guns were sold, the manufacturers were violating a state statute against being a “criminal nuisance.”

In a 2-1 decision, the 2nd Circuit U.S. Court of Appeals yesterday said that the city’s suit against the gun manufacturers was precluded by a federal law, the Protection of Lawful Commerce in Arms Act, that went into effect in 2005 and protects firearm manufacturers and distributors from being sued for the misuse of a firearm.

In addition to the manufacturers, Mr. Bloomberg is suing several out-of-state gun stores and pawn shops that the city claims are responsible for selling a disproportionate number of the firearms recovered in crimes in New York City. The first of those trials is scheduled to begin this month.

Judges Roger Miner and Jose Cabranes were in the majority. Judge Robert Katzmann dissented, writing that a lawsuit brought under the “criminal nuisance” statute might be allowed under an exception to the Protection of Lawful Commerce in Arms Act.