SELECTIVE INCAPACITATION,THREE STRIKES,AND THE PROBLEM OF AGING PRISON POPULATIONS: USING SIMULATION MODELING TO SEE THE FUTURE*

Research Summary: The growth of prison populations over the last three decades is a great source of concern for policy makers and observers. One mechanism by which this growth occurs is via sentencing reforms that extend length of stay for certain categories of offenders. This has the effect of aging prison populations, which is problematic for many reasons. Apart from the increased financial burdens entailed in caring for older prisoners, it is also important to consider the intent of reforms in evaluating them. Of late, sentencing reform has become increasingly focused on the selective incapacitation of dangerous offenders. Policies that have the effect of aging the prison population are problematic from this perspective due to the diminishing returns realized with respect to incapacitation as offenders age. Dynamic systems simulation analysis is employed to investigate the likely consequences of recent sentencing reforms that increase length of stay for some offenders. These analyses indicate that the effects of recent reforms may not be as dramatic as some observers have predicted, but they suggest that the consideration of alternatives to incarceration for elderly offenders is warranted from the standpoint of cost considerations as well as that of selective incapacitation. Policy Implications: The results indicate that California's Three Strikes law will not accelerate the rate of growth of the elderly prison population. However, even without increasing the proportional representation of elderly prisoners, the number of elderly prisoners is expected to grow substantially over the next three decades. These prisoners will strain criminal justice system resources while presenting little public safety threat. State criminal justice policy makers and their constituents should closely examine laws that impose very long stays without discretionary release, as these statutes may contribute to the production of elderly prisoners. This problem is particularly pronounced in Three Strikes and other habitual offender laws that use retrospective methods to identify habitual offenders. Additionally, the effects of reforms lengthening stay for some offenders must be considered in light of cumulative effects of sentencing reform resulting in changes to the demographic structure of the prison population overall. Dynamic systems simulation modeling is presented as a valuable policy‐making tool, as it allows the policy analyst to examine the potential impacts of laws in the absence of data suitable for conventional statistical analyses.