Let's Enforce The Laws We Have On The Books

From 2011, and I'm sure not much has changed: weapons prosecutions decline to lowest level in a decade.

The latest available data from the Justice Department show that during January 2011 the government reported 484 new weapons prosecutions. This is the lowest level to which federal weapons prosecutions have fallen since January 2001, when they were 445 at the time President George W. Bush assumed office.

Later in the article:

None of the districts with the largest cities in the country make the top 10. In contrast, those districts ranking in the bottom tier contain a number of large metropolitan areas. These include the Northern District of Illinois (Chicago) ranked 80th, the Central District of California (Los Angeles) ranked 83rd, the Northern District of Georgia (Atlanta) ranked 85th, Massachusetts (Boston) ranked 86th, and the Northern District of California (San Francisco) ranked 87th. 

Wow, talk about chickens coming home to roost. 

I think if one connects the dots, one could sort out the reason for the low prosecution in Chicago, Boston, and San Francisco. The dots are easy to connect.