Updated

New York City's murder, rape, robbery and aggravated assault rates rose last year according to preliminary FBI data, with murders alone increasing by more than 12 percent. But instead of concentrating on crime in New York City, Mayor Bloomberg just spent $100,000 of the NYPD's budget sending police to Arizona to buy guns at a gun show.

The "sting" was a waste of money that misleads Americans and did nothing to reduce crime. Talk about an aggressive publicity stunt. Arizona officials had not been informed of the operation, which meant that any potential crimes uncovered by the New York City officers could not be prosecuted.

But, instead of spending $100,000, Bloomberg could have learned what he did for the price of a phone call or an Internet search. Arizonans, like residents in 31 other states, can buy guns from private individuals without a criminal background check, just an Arizona driver's license to demonstrate residency. However, if they sell a gun to someone who they suspect will use it to commit a crime, they risk becoming liable for that crime.

John Feinblatt, a Bloomberg adviser, asserted: “The background check system failed in Arizona, it failed in Virginia and it fails in states around the country. If we don’t fix it now, the question is not whether another massacre will occur, but when.”

Nevertheless, background checks on the private sales of guns would have failed to stop the Tucson, Arizona shooting because the killer, Jared Loughner, passed his background check at a gun store. He had never been convicted of a crime, never been adjudicated as being a danger to himself or others, and he had not been involuntarily committed for mental illness. Thus, he would have been able to get a gun in any state, including New York, where he had been a resident.

Background checks do not stop bad guys from getting guns. Instead, the Brady Act background checks for gun purchases, in place since 1994, are a problem for law-abiding citizens. Hardly ever do background checks deny guns to criminals. Over 99.9 percent of purchases initially flagged as being illegal under the law were later determined to be misidentified.

Take the numbers for 2008, the latest year with data available. The 78,906 initial denials resulted in only 147 cases involving banned individuals trying to purchase guns. Of those 147 cases, prosecutors thought the evidence was strong enough to prosecute only 105, and they won convictions in just 43. But few of these 43 cases involved career criminals or those who posed real threats. The typical case was someone who had a misdemeanor conviction for an offense he didn't realize prevented him from buying a gun.

It is hardly surprising that not a single academic study by economists or criminologists has found that the Brady Act or any state background checks has reduced violent crime. Even those who aren't prevented from buying a gun face delays in getting approved. Eight percent of the National Instant Criminal Background Check System checks are "not resolved immediately."

Five percent of those checks take up to 3 business days, and 3 percent take even longer, though these further delays can't stop one from obtaining a gun at that point.

For gun shows, such background checks would be more than a nuisance because gun shows usually only last for a single weekend. Preventing the sale for that long often means that the transaction will not be able to take place.

According to my research, imposing this requirement cuts down the number of gun shows by about 20 percent. The incorrect denials and delays could be a real safety problem for those who are being stalked or threatened and need protection quickly.

Contrary to public perception, very few criminals obtain their guns from gun shows. This was shown in an extensive survey conducted by the Bureau of Justice Statistics in 1997, with interviews of 18,000 state prison inmates. Only a trivial 0.7 percent indicated that they had obtained their guns at a gun show. Including flea markets, the total rises to just 1.7 percent.

Instead, the overwhelming majority of guns that criminals obtain come either from "friends and family" (40 percent) or "on the street or from illegal sources" (39 percent).

The undercover operation run by Mayor Bloomberg also plays into the entire mythology that has developed around the 33 round magazine based on the claim that Loughner only had to reload because he ran out of bullets.

In fact, the killer’s gun jammed precisely because he used such a large capacity magazine. The long spring used in this high capacity magazines simply didn’t have enough force to properly push the last couple of bullets into the gun. Given that it can take just a couple of seconds to replace a magazine, the killer would have likely been able to fire more rounds if he had brought several smaller magazines.

Mr. Bloomberg makes a big deal about the guns purchased at the guns shows as having characteristics desired by criminals: great stopping power, light weight, concealable. But those are all characteristics that law-abiding citizens value. A small, 120 pound woman will value stopping a 200 pound male criminal before he can grab her.

The 6.2 million Americans who legally carry concealed handguns value light weight concealable guns.

Mr. Bloomberg's P.R. stunt did nothing to stop crime. Wasting $100,000 is bad enough. Today he demanded that the federal government itself spend even more money enforcing these laws.

Hopefully, Americans won't follow his policies and end up wasting lots more money on policies that divert police resources and time from things that do work.

John R. Lott, Jr. is a FoxNews.com contributor. He is an economist and author of the just released revised edition of "More Guns, Less Crime" (University of Chicago Press, 2010).