The New York Times, May 23, 2011 by Richard A. Oppel Jr.
http://www.nytimes.com/2011/05/24/us/24crime.html?scp=2&sq=Berkeley&st=nyt
For those who believed that higher incarceration rates inevitably led to less crime, “this would also be the last time to expect a crime decline,” he said. “The last three years have been a contrarian’s delight—just when you expect the bananas to hit the fan,” said Mr. Zimring…. But he said there was no way to know why—at least not yet.