Right on Crime Policy Director Marc Levin and Policy Analyst Derek Cohen write in The Crime Report:

The National Academies’ exhaustive report, “The Growth of Incarceration in the United States: Exploring Causes and Consequences,” released last month, covers nearly the entire body of scholarship on the causes of the incarceration boom.

The causes, as identified by the authors, derive from a charged political arena favoring longer sentences, the trend towards harsher methods of punishment, and the rapid development of increasingly punitive drug laws.

Certainly, the last four decades of criminal justice policy reflect this.