The Deterrent Effects of Prison: Evidence from a Natural Experiment

Abstract

The Collective Clemency Bill passed by the Italian Parliament in July 2006 represents a natural experiment to analyze the behavioral response of individuals to an exogenous manipulation of prison sentences. On the basis of a unique data set on the postrelease behavior of former inmates, we find that 1 month less time served in prison commuted into 1 month more in expected sentence for future crimes reduces the probability of recidivism by 0.16 percentage points. From this result we estimate an elasticity of average recidivism with respect to the expected punishment equal to - 0.74 for a 7-month period. (c) 2009 by The University of Chicago. All rights reserved..

Theft and Deterrence

“…This identification strategy has been employed by Corman andMocan (2000, 2005). The third strategy is to find a natural experiment which generates a truly exogenous variation in deterrence, as in Di Tella and Schargrodsky (2004), who use the increase in police protection around Jewish institutions in Buenos Aires after a terrorist attack to identify the impact of police presence on car thefts, and Drago, Galbiati and Vertova (2009) Although these empirical strategies have permitted researchers to refine and improve upon earlier estimates, a convincing natural experiment is very difficult to find, the validity of any instrumental variable can always be questioned, and one can argue that if policy makers have foresight about future crime rates, low frequency data could also suffer from simultaneity bias. 3 In this paper, we use an economic experiment to investigate individual responses to unambiguously exogenous changes in the rewards and penalties of criminal behavior.…”

Estimating the Deterrent Effect of Incarceration Using Sentencing Enhancements

“…They bound allowable elasticities consistent with their data and model to have a magnitude no greater than -.13, although their preferred parameter values yield elasticities close to 0. The largest recent empirical elasticity estimates come from Drago, et al (2009) using Italian data, where they find a magnitude of -.74 for 7 months. This may be an indication that the substantially lower incarceration rate in Italy makes it difficult to extrapolate to the United States.…”

“…Helland and Tabarrok (2007) investigate the effects of California's three strikes law and find a 3 Some of the criticism seems to originate from a misunderstanding of the triple difference strategy in Kessler and Levitt (1999). decrease in arrests of around 20% among felons with two strikes. Drago, Galbiati, and Vertova (2009) use a natural experiment in Italy that induced individual-level variation in sentencing to estimate a deterrence effect.…”

Exclusion and Reintegration in a Social Dilemma

“…To summarize, cooperation is higher in the presence of a risk of exclusion and increases 23 25 Note also that time has no significant effect. This is in contrast with standard experiments on monetary punishment in public goods game in which sanctions occur from the very beginning the game to impose a norm in the group.…”

“…The first contribution is comparing the impact of various lengths of exclusion on the cooperative behavior of excluded 5 For example, an inmate with a long prison sentence is more at risk of recidivism due to his own characteristics that led to his exclusion, to peer effects in prison and to stigma on the labor market. To address these issues, Drago et al, 2009 used a natural quasi-experiment in Italy where a law implemented an immediate three-year reduction in detention, giving a random manipulation of the length of the remaining sentence at the date of the pardon. They found that longer sentences had ex ante a higher deterrent effect on recidivism, but the inmates who stayed longer in prison responded less to the variation in incentives.…”