Incapacitation

One of the most robust findings in criminal justice research is the heterogeneity in offending rates and in deviant behavior generally, across the population. Longitudinal research studies in various countries such as the United States, Canada, England, Denmark, and New Zealand have found that when a group of individuals born the same year (a "birth cohort") are monitored from birth to adulthood a small percentage, typically under 10 percent, account for the majority of crimes generated by the entire cohort. For example, in the now famous study of a birth cohort of Philadelphia boys by Wolfgang and colleagues, 6 percent of boys were responsible for 52 percent of all police contacts generated by the cohort.

In longitudinal cohort studies the vast majority of cohort members do not report any criminal activity when interviewed and do not have an official criminal record. Among those with at least one reported criminal justice contact, 15 to 20 percent often account for about half of the total crimes. Comparable findings have been obtained when analyzing reported offending rates of prison inmates (Chaiken and Chaiken).

The subset of offenders with substantially higher offending rates than the average offender has been the subject of much criminological research, for not only do they represent the natural population in which to study the effect of various factors influencing onset and termination of criminal behavior, but they also constitute a natural target for incapacitation (as well as special deterrence and rehabilitation).

Capitalizing on the existence of high rate offenders, and seeking to achieve large incapacitation levels with low incarceration rates, the controversial policy of selective incapacitation was advanced in the early 1980s by Greenwood and Abrahamse. In the area of incapacitation and even in criminal justice policy generally, few scholarly proposals have generated as much controversy and heated exchanges as the idea of selectively incarcerating offenders based in part on their expected future crimes. Ethical and legal concerns, coupled with the inability to prospectively distinguish with accuracy high and low rate offenders, have precluded the implementation of selective incapacitation policies, even on a trial basis. Instead, what happened was a toughening of criminal sanctions across the board but especially for repeat offenders with multiple prior convictions. For example, the three-strikes-andyou're-out statutes previously discussed impose very long sentences on offenders with two or more prior convictions, presumably because those prior convictions indicate a high criminal propensity. However, the application of this scheme does not call for any predictions of future criminality and treats exactly alike two offenders with the same prior record and the same current offense. Still the foundation of this policy is the existence of chronic offenders whose incapacitation allegedly yields high social returns. It is ironic that to overcome the ethical and legal concerns associated with assigning incarceration terms partly based on unreliable predictions of what an offender may do in the future, we essentially adopted the policy that two prior strikes automatically qualify a convictee as a chronic offender and thus a good target for long incapacitation. Clearly, many false positive predictions result from this policy and apparently its only redeeming grace is that the prediction it implicitly relies on is based on past rather than future behavior.

Since around 1990, much has been learned about high rate offenders as a result of the development of new statistical techniques applied to data sets collected from longitudinal studies. The joining of developmental theories in psychology with the criminal career approach of the 1980s has been particularly fruitful and is a promising source of new policy insights. The criminal career paradigm brought attention to the dimensions of individual offending, namely age of onset of offending, frequency and seriousness of offending, and termination of offending. The approach was particularly helpful in recognizing that crime control policies could differentially affect each of the dimensions of individual offending, and that in turn particular attributes of criminal careers could affect the effectiveness of crime control policies. For example, early on the limits of incapacitation due to of career termination were recognized. Developmental psychology and longitudinal research methods have infused the criminal career paradigm with a theoretical foundation and a much more powerful dynamic outlook. The resulting new approach, often referred to as "criminal trajectory analysis," looks closely at the interaction of personal attributes and external events in the unfolding of an offender's course of criminal acts. The approach is also dynamic in that it seeks to determine how aging affects an individual's trajectory. Important pioneering works in this new tradition are those of Terri Moffitt from the developmental psychology perspective, and of Nagin and Land from the field of quantitative criminology.

The criminal trajectory approach has confirmed that not all offenders have the same propensity to engage in criminal behavior and in deviance generally. Offenders vary in their frequency of deviance involvement as well as in the number of years during which they engage in those behaviors. Typically, these studies find three distinct groups among the members of a cohort with delinquent acts, each with a typical "offending trajectory": adolescent-limited offenders, low-level chronic offenders, and high-level chronic offenders (Nagin et al.; Fergusson et al.). These groups are different in a number of ways, for example the adolescent-limited typically start offending in early adolescence and generally stop offending altogether in early adulthood. In contrast, high-level chronic offenders have their criminal onset during childhood and continue their involvement in crime and deviant behavior for long periods of time. Oftentimes this group consists mostly of children with neuropsychological deficits who have faced disadvantageous social and family environments from day one in their lives.

A very important insight from this new generation of longitudinal studies pertains to the relationship between age and criminal involvement. Even high-level chronic offenders show a declining criminal trajectory after a certain age, contradicting past notions that high-rate offenders maintain a constant rate of offending while criminally active. This insight is important as it makes clear that some incarceration time will have either declining returns or even, possibly, no returns. Beyond a certain point in an offender's incarceration term, he would not commit additional offenses if free, and thus the rationale for incapacitating him is lost.

The new longitudinal studies may eventually provide us with better ways to prospectively identify high-level chronic offenders among all offenders. The development of that ability need not entail the return of proposals of selective incapacitation, and in fact there is presently no literature in print exploring that possibility. Rather, as we learn to precisely identify the set of conditions, from conception to adulthood, that turn an individual into a high-rate chronic offender, society may be moved to intervene early, and not necessarily in a criminal justice context, to undermine the host of conditions pushing individuals into a trajectory of sustained offending.