NYC Mayor Cracks Down on Illegal Gun Sales... in Arizona?

New York City Mayor Michael Bloomberg pledged to strengthen control laws after the Jan. 8 Tucson shooting that left six dead and 13 injured, including Arizona Congresswoman Gabrielle Giffords. But while many may have thought the mayor would carry out his illegal gun crack down in New York, Bloomberg sent some of New York's finest to Arizona to carry out an undercover investigation, part of broader effort by Bloomberg to crack down on illegal gun sales nationwide.

According to the New York Times, Bloomberg's undercover task force was most recently sent to the Jan. 23 Crossroads of the West gun show in Phoenix.

“The background check system failed in Arizona, it failed in Virginia and it fails in states around the country,” said Bloomberg advisor John Feinblatt, referring to other investigations. “If we don’t fix it now, the question is not whether another massacre will occur, but when.”

Private, unlicensed sellers are not required to run federal background checks, but it is a violation of federal law to sell guns to people who may be felons or mentally ill.

In two instances, the New York undercover officers specifically said before buying a gun, “I probably couldn’t pass a background check,” but were still sold guns, city officials said.

In a third case, an investigator bought a Glock pistol and two high-capacity magazines like the ones used in the Tucson shooting. Such purchases were made without any background check but were perfectly legal. ...

Crossroads of the West holds dozens of gun shows annually, in Arizona, California, Nevada and Utah. “When we find someone who isn’t complying with the law, we ask them to leave or don’t allow them back,” said Bob Templeton, president of the gun show.

After similar transgressions were uncovered at gun shows in other states, some operators entered into agreements with New York City requiring that private sellers arrange background checks of all gun buyers.

But is it Bloomberg's responsibility to try and enforce federal laws when his jurisdiction is technically limited to the city of New York?

You'll recall that when the state of Arizona tried to help enforce federal immigration laws, the Obama Justice Department launched a lawsuit to block their efforts.

On the one hand, Bloomberg notes that his administration is working to raise awareness of how easily people can purchase firearms at a gun show.  But on the other, Arizona lawmakers were similarly calling on the federal government to crack down on illegal immigration in their own state.

Why is one effort seemingly okay while the other is being hauled off to court?

UPDATE:

Arizona's Sheriff Joe Arpaio weighed in Monday evening via Twitter: