After writing my last Freakonomics post, I received a phone call from a police officer who began his career in Chicago.

Carl, the 54-year-old cop, started working in Chicago’s inner cities at the height of the crack epidemic. He transferred to the suburbs of Seattle for a lifestyle change — “I was tired of getting shot at,” he said matter-of-factly.

I had promised readers of this blog that I would ask about the creative, informal ways police respond to crime — sometimes even tolerating certain anti-social or criminal behavior for (presumed) larger gains. Carl was eager to respond.