USING RANDOM JUDGE ASSIGNMENTS TO ESTIMATE THE EFFECTS OF INCARCERATION AND PROBATION ON RECIDIVISM AMONG DRUG OFFENDERS*

Most prior studies of recidivism have used observational data to estimate the causal effect of imprisonment or probation on the probability that a convicted individual is rearrested after release. Few studies have taken advantage of the fact that, in some jurisdictions, defendants are assigned randomly to judges who vary in sentencing tendencies. This study investigates whether defendants who are assigned randomly to more punitive judges have different recidivism probabilities than defendants who are assigned to relatively lenient judges. We track 1,003 defendants charged with drug-related offenses who were assigned randomly to nine judicial calendars between June 1, 2002 and May 9, 2003. Judges on these calendars meted out sentences that varied substantially in terms of prison and probation time. We tracked defendants using court records across a 4-year period after the disposition of their cases to determine whether they subsequently were rearrested. Our results indicate that randomly assigned variations in prison and probation time have no detectable effect on rates of rearrest. The findings suggest that, at least among those facing drug-related charges, incarceration and supervision seem not to deter subsequent criminal behavior.