More Time, Less Crime? Estimating the Incapacitative Effect of Sentence Enhancements

Sentence enhancements may reduce crime both by deterring potential criminals and by incapacitating previous offenders, removing these possible recidivists from society for longer periods. I estimate the incapacitative effect of longer sentences by exploiting a 2001 change in Maryland's sentencing guidelines that reduced the sentences of 23-, 24-, and 25-year-olds with juvenile delinquent records by a mean of 222 days. I find that, during this sentence disenhancement, offenders were, on average, arrested for 2.8 criminal acts and were involved in 1.4-1.6 serious crimes per person during the period when they would have otherwise been incarcerated. Although my findings are significantly lower than previous estimates of incapacitation, I find that, on the margin, the social benefit of the crimes averted by incapacitation is slightly higher than the marginal cost to the state of imposing a 1-year sentence enhancement. (c) 2009 by The University of Chicago. All rights reserved..