Second, retrospective analysis of the statistical effect of increasing prison populations through across-the-board increases in prosecution and the length of sentencing suggests that the relationship between merely increasing prison populations and decreased crime rates is insufficient to justify focusing on this approach. Since a relatively small percentage of criminals (even serious criminals) account for a disproportionately high percentage of crime (Visher, 1987), merely increasing across-the- board imprisonment of criminal offenders is not an approach likely to reduce crime substantially.
Specifically, increasing prison populations by 10 to 20% through collective incapacitation corresponds to only 1% reduction in crime; similarly, even the implementation of increased imprisonment through selective incapacitation is projected to produce only marginally better results in the neighborhood of perhaps 5% crime reduction associated with a 5 or 10% increase in prison populations (Visher, 1987).
On a cost-benefit analysis alone, (let alone the ethical issues raised by this approach), the implications of achieving crime reduction primarily through expanding prison populations are not particularly advantageous.
3. What is the difference between collective and selective incapacitation? How large is the incapacitation effect? Has the “prison experiment” been a success or a failure?
Collective incapacitation refers to the crime reduction approach of increasing prosecution and sentencing of all criminal offenders across the board. Selective incapacitation refers to the targeted approach to reducing crime by increasing prosecution and sentencing of those offenders whose past criminal history, other behavioral patterns, and specific offenses are statistically (and logically) associated with higher likelihood of future criminality than that associated with all offenders in general (Visher, 1987).
The collective incapacitation effect is “modest” at best (Visher, 1987) and quite possibly nonexistent altogether. The selective incapacitation effect is greater, because it focuses on those specific crimes, behavioral patterns, and on elements within specific crimes (such as the use of a knife, injuries to victims, etc.) statistically associated with higher rates of criminality and recidivism. Unfortunately, increasing prison populations (even through selective rather than collective incapacitation) is likely insufficient to result in crime reduction rates that justify that approach to reducing crime in society (Visher, 1987).
In general, the “prison experiment” has been a failure because it has not produced the significant decrease in crime rates in society envisioned by its proponents and architects. According to Visher (1987), a combined strategy that includes equal attention and effort directed at incorporating other crime control strategies such as prevention, deterrence, and rehabilitation is more likely to achieve the goal of significant crime reduction than a directed focus on the “lock em up” strategy in general or on either form of incapacitation, in particular.
Visher, C.A. (1987)..