The Effect of Incarceration on Re-Offending: Evidence from a Natural Experiment in Pennsylvania.

Objectives: This paper uses a sample of convicted offenders from Pennsylvania to estimate the effect of incarceration on post-release criminality. Methods: To do so, we capitalize on a feature of the criminal justice system in Pennsylvania-the county-level randomization of cases to judges. We begin by identifying five counties in which there is substantial variation across judges in the uses of incarceration, but no evidence indicating that the randomization process had failed. The estimated effect of incarceration on rearrest is based on comparison of the rearrest rates of the caseloads of judges with different proclivities for the use of incarceration. Results: Using judge as an instrumental variable, we estimate a series of confidence intervals for the effect of incarceration on one year, two year, five year, and ten year rearrest rates. Conclusions: On the whole, there is little evidence in our data that incarceration impacts rearrest. [ABSTRACT FROM AUTHOR]