Thanks to a December 5 ruling by the U.S. Court of Appeals for the 3rd Circuit, New Jersey's ban on gun magazines that hold more than 10 rounds took effect on December 10. By that date, all owners of heretofore legal "large capacity magazines" (LCMs) were required to surrender them to police, render them inoperable, modify them so they cannot hold more than 10 rounds, or sell them to authorized owners. Those who failed to do so are guilty of a fourth-degree felony, punishable by a maximum fine of $10,000 and up to 18 months in prison.

How many of New Jersey's 1 million or so gun owners have complied with the ban by turning LCMs in to law enforcement agencies? Approximately zero, judging from an investigation by Ammoland writer John Crump. Crump, an NRA instructor and gun rights activist, "reached out to several local police departments in New Jersey" and found that "none had a single report of magazines turned over." He also contacted the New Jersey State Police, which has not officially responded to his inquiry. But "two sources from within the State Police," speaking on condition of anonymity, said "they both do not know of any magazines turned over to their agency and doubted that any were turned in."

I also contacted the state police, where Sgt. Jeff Flynn told me they have received "zero" LCMs. Flynn said I should address any other questions about the law to the Attorney General's Office, which I did. Leland Moore, a spokesman for the Attorney General's Office, said I should talk to the state police. Crump got the same runaround. When I pointed that out, Moore said by email, "We do not have information on how many LCMs have been received by local police in the hundreds of municipalities across NJ. That's not something we track."

Law enforcement agencies, of course, would not necessarily know about gun owners who complied with the law in one of the other approved ways. It's possible that some gun owners destroyed their suddenly illegal magazines, modified them, or transferred them to, say, gun owners in other states or retired cops, who are exempt from the magazine ban. But there is no direct evidence of that either.

How many contraband magazines are we talking about? That's hard to say, but Crump notes that "the standard magazine for an AR-15 holds 30 rounds," while the Glock 19, "which is the most popular pistol in the United States, holds 15 rounds." The 3rd Circuit likewise noted that "LCMs often come factory standard with semi-automatic weapons." Based on the number of gun owners in the state, the number of guns they own on average, and sales figures for guns that are sold with magazines holding more than 10 rounds, Crump calculates that New Jersey residents owned "at least 2 million" LCMs before the ban was enacted. So even if we assume that half of those were destroyed or transferred, there are still 1 million or so illegally owned by otherwise law-abiding people in New Jersey.

As J.D. Tuccille has periodically reminded us, noncompliance with arbitrary gun restrictions seems to be the rule rather than the exception. Some gun owners may be deliberately disobeying the law, while others may not be aware that the products they legally purchased and have legally owned for years are now evidence of a felony.

According to Crump's state police sources, "the plan that has been discussed among officers is only to file charges against people who are guilty of other crimes." Plans can change, of course, but if the only LCM owners who are treated as felons are the ones who come to the attention of the police for other reasons, that is not exactly reassuring. After all, a routine traffic stop could result in a felony charge against someone with an LCM in his car. Likewise for an LCM owner who makes the mistake of inviting police officers to his home—in response to a burglary, say.

Former NYPD Commissioner Bernard Kerik is outraged by New Jersey's "crazy" magazine ban, but only because he worries that it could be enforced against off-duty police officers. The original version of the law included an exemption for "any law enforcement officer while actually on duty or traveling to or from an authorized place of duty," who was allowed to have a magazine holding up to 15 rounds. An amended version that Gov. Phil Murphy is expected to sign soon extends that exemption to officers who are off duty.

On Twitter last Friday, Kerik complained that Murphy "is endangering the life of every off duty NJ cop! Gang bangers, drug thugs and really bad guys don't give a damn about magazine capacity…So he takes the good guy's ammunition, and the bad guys are loaded for bear!" Last Sunday on Fox News, Kerik vented some more. "You're taking the ability away from the cops to possess the rounds they may need in a gun battle," he said. "That's insane."

Something similar happened with the seven-round magazine limit that New York legislators hastily enacted in 2013, except in that case it was former cops who were overlooked. They angrily demanded the double standard to which they were accustomed, and the legislature gave it to them a few months later. Notice that Kerik readily concedes New Jersey's magazine limit will have no impact on criminals, and he takes it for granted that the difference between 10 and 15 rounds could be the difference between life and death for someone using a gun in self-defense. Yet somehow that extra margin of safety is intolerable for citizens without badges.

State Policemen's Benevolent Association President Patrick Colligan told the Trenton radio station WKXW the omission of an exemption for off-duty cops "was simply an error," adding that "quite frankly, I think just the date, the December 10 date, caught up with everybody." It seems doubtful that police will accept that excuse from ordinary people who own the magazines that only the privileged few are allowed to possess.

[This post has been updated with responses from the New Jersey State Police and the Attorney General's Office.]