From the Second Amendment Foundation:

A letter to the office of New York Mayor Michael Bloomberg from the U.S. Department of Justice scolding the mayor’s infamous 2006 gun sting operation and advising that Bloomberg’s administration could face “potential legal liabilities” over such stings was called a “significant victory” against the Big Apple mayor’s anti-gun antics by the Second Amendment Foundation.

From the National Shooting Sports Foundation:

The Department of Justice letter serves to confirm what we have said all along, that the unauthorized and reckless conduct of Mayor Bloomberg in having private investigators conduct so-called sting operations in support of filing civil lawsuits will, and in fact has, interfered with ongoing criminal investigations into gun trafficking and jeopardized the lives of law enforcement officers and witnesses.

From the NRA:

NRA has always maintained that Mayor Bloomberg overstepped his boundaries and possibly broke the law in conducting these sting operations, and we expressed our concerns to ATF immediately. NRA is grateful that ATF has reviewed the matter and concluded that no further action is warranted against these firearms retailers.