More Time, Less Crime? Estimating the Incapacitative Effect of Sentence Enhancements
利用2001年马里兰州量刑指南改革中特定年龄罪犯减刑222天的自然实验，估算出每名罪犯在应被监禁期间平均犯下2.8起刑事犯罪和1.4-1.6起严重犯罪，发现剥夺犯罪能力的社会收益略高于一年加刑的边际成本。
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.