Kent posted an admonition to take with a grain of salt (or maybe ten grains) any solemn pronouncement you hear or read in which "experts" release a "study" that shows X.
As usual, Kent nails it. Academia, including legal academia, is chock full of largely self-annointed (and media-annointed) "experts" with one thing in common: a Leftist and pro-criminal bias. This is not uniformly true (for example, see Prof. John Pfaff's work noted by Steve Erickson here, or Campbell Law Prof. Zach Bolitho), but a pro-criminal bias is endemic in both law schools and think tanks.
What this brought to mind was a bunch of "experts" often cited in the liberal press, such as the Washington Post (just today) and the New York Times. That would be the Brennan Center operating out of New York City.
The Brennan Center is to incarceration what the DPIC is to the death penalty: An organization that fronts itself as a source of information while making less prominent its actual purpose -- to crusade for the interests of criminals. This is very much why it is sought out for its "expert" views (while CJLF occupies Linda Greenhouse's doghouse and, according to her, should be shunned).
It was the Brennan Center that discovered, contrary to the findings of every credible researcher who has looked at the question (not to mention common sense), that the country's markedly increased willingness over the last generation to incarcerate people who commit crime has had next to nothing to do with the marked decrease in crime. I covered the Brennan Center's preposterous "study" here.