As many as half of the most serious gun arrests by the NYPD are dismissed or not prosecuted in some of the city's more violent boroughs, according to court statistics.
State court statistics show that last year there were more cases of the most serious gun charge, criminal possession of a weapon in the second degree, tossed out in the Bronx and Brooklyn than in the other boroughs: 41.5 percent in the Bronx and 31.9 percent in Brooklyn.
Combined with arrests that prosecutors decline to prosecute, the Bronx saw 53 percent of those gun arrests shelved, while the number was 40 percent in Brooklyn, state records show.
The problems stem from a combination of factors ranging from the way cops sometimes lump defendants together or mishandle evidence to decisions by prosecutors to let federal courts handle the cases and impose stricter sentences, sources and experts said.
In addition, police have been complaining about the way prosecutors use diversion programs, which are designed to give first offenders a second chance so they don't get criminal records, and when seemingly high-risk gun defendants are allowed out on the street where they commit serious crimes, sources said.
Last year, NYPD Commissioner William Bratton indirectly criticized the courts for not giving some defendants convicted of serious gun offenses, such as criminal possession of a weapon in the second degree, at least the minimum mandatory sentence.
"There are some cases where sentencing of individuals carrying a gun is not significant enough, in the sense that they are not doing the mandatories [sentences] if you will," Bratton said in talks with reporters.
NYPD spokesman Stephen Davis declined to comment.
Under state law, first offenders get a mandatory minimum of 3.5 years in prison for second-degree criminal possession of a weapon while the lesser count will draw two years, said Brooklyn defense attorney James DiPietro.
But one high-ranking assistant district attorney who didn't want to be identified said many gun possession defendants are 17 years old or younger, and if they are treated as youthful offenders, there is no mandatory minimum term.
"For every 35-year-old caught there are two 17-year-olds," said the prosecutor, adding that some judges are reluctant to sentence a 17-year-old gun defendant without a prior record to a mandatory term.
But state data show that, while in some cases judges don't sentence gun defendants to the mandatory minimum prison terms, the large majority of serious gun convictions around the city lead to substantial prison time either at or above the mandatory minimum terms.
Bratton also has complained about prosecutorial diversion programs, saying that in at least one case, a defendant in the program was out on bail and got picked up for a gun used in five shootings.
"So there is an individual who should never be in diversion program in the first place," Bratton said earlier this year.
However, a city prosecutor familiar with the case, which happened to be in Brooklyn, said the defendant Bratton complained about was actually in diversion for credit card fraud, not gun possession. The gun was later found in his apartment and not out on the street, the official said.
A spokeswoman for Brooklyn District Attorney Kenneth Thompson said he has discussed the diversion program and other police concerns with Bratton. In gun cases, while the NYPD is consulted, Thompson's staff makes the final decision and then passes it along to a judge, the spokeswoman said.
In most diversion cases, "the results have been mostly successful, with a low percentage of re-offenders," added the spokeswoman.
Police, both publicly and in private, have also complained about the way serious gun cases get dismissed or pleaded down to less serious offenses, particularly in the Bronx and Brooklyn, which happen to be two boroughs that last year saw a combined 73.6 percent of shooting incidents.
According to prosecutors and defense attorneys, high dismissal rates on gun arrests don't mean that district attorneys are soft on the gun possession offenses.
Many of the gun cases in the Bronx, for example, are dismissed because Manhattan federal prosecutors eventually take them as part of a program known as "Trigger Lock," which allows prosecutors to get more leverage of suspects through stringent federal sentencing law, said one Bronx prosecutor. Bronx juries also have a reputation for being skeptical of cops, said the prosecutor.
Brooklyn federal prosecutors also take Trigger Lock cases, but much less frequently. The problem, both prosecutors and police officials said, is that federal judges in Brooklyn have questioned the credibility of police testimony in gun arrests in some controversial cases.
"They [police] had issues with bad rulings from judges who found officers had incredible explanations ," said a Brooklyn prosecutor.
Overcharging by police or lumping all defendants together is one issue that legal experts said accounts for high rates of dismissals in second-degree weapons possession cases. This is seen as particularly true in gun arrests at the airports or where a weapon is found in an apartment or car and everyone is charged with possession.
"There is no wiggle room," said former Manhattan Assistant District Attorney Elizabeth Crotty. "If someone has a gun in a bag and they are sitting in a car, how are they to know a person has a gun?"
A large number of gun arrests also occur at LaGuardia and Kennedy airports because travelers from a state where gun possession is legal wrongly assume they can travel to the city with a weapon. Even if the gun is put in checked baggage or carried on in a purse or briefcase, the traveler can get arrested.
"We find these are legitimate citizens," said the Queens prosecutor, whose office handles about 50 to 60 airport gun cases a year and often cuts loose defendants with a conditional discharge and a fine.
More problematic are failures by police to get guns processed for fingerprints, which angers jurors and is something that can destroy a case, said DiPietro, adding that he has seen such omissions in 80 percent of gun possession cases he handled.
"When cops don't dust guns for latent fingerprints, it makes a defense attorney's life much easier," DiPietro said.