In a policy area that is as charged with emotion as any, debate about the proper goals of criminal justice and the criminal
sanction is frequently dominated by the uninformed and the politically expedient. There is little doubt that the idea of
incapacitating criminals has captured the imagination, if not the pocket books, of the American people and many of their
representatives. Yet it is not beyond the realm to wonder, as many scholars do, whether prescriptions to focus the criminal
sanction exclusively on incapacitation seek a quick fix, perhaps carrying high hidden and long-term costs, that in the long run
will prove no more effective in reducing crime than any other possible reform. In the face of this, Professor William Spelman
from the LBJ School, attempts to provide a rational econometric analysis of incapacitation to demonstrate that when utility
issues are systematically investigated, pursuing policies of broad based incapacitation are much more of an economic gamble
than pursuing policies of selective incapacitation, where specific types of criminal offenders are targeted. Indeed, the central
focus of this book is not on the incapacitative effects of crime control policies per se, but rather the economic efficiency of
pursuing some kinds of incapacitation-oriented policies rather than others.
This is not a book for the faint of heart when it comes to statistics and mathematical modelling. Its overall methodology is one of
identifying the types of data that would be needed to make predictions or estimates of the crime-reduction effects of
incapacitation, to review the existing empirical literature and sources of these types of data to establish the range of existing
estimates, to use these estimates to make educated guesses that can be plugged into models which estimate crime-reduction
effects, and to conduct some sensitivity analyses to investigate how dependent the crime-reduction estimates are on particular
types of data. For example, starting in Chapter 2, Spelman addresses the need to estimate the number of offenses that criminal
offenders commit per year, a rather important piece of information if one is to make estimates of the number of crimes not
committed due to incapacitation. After reviewing existing data and assessing specific threats to the validity of these data,
Spelman develops a methodology to adjust or weight existing data to correct for biases. As much as anything else, Chapters 2
through 5, however, describe how much uncertainty there is in existing estimates of critical characteristics of the criminal
population.
Chapter 3 focuses on the offense rate -- the number of crimes committed per offender per period of time -- an important factor
in the ultimate computation of a benefit/cost ratio associated with incapacitation. Chapter 4 examines "the criminal career," in an
effort to estimate the frequency of crimes offenders commit at different ages. Spelman finds that high and low rate offenders are
less likely to drop out of criminal activity at any given time than offenders with moderate offense rates. Chapter 5 focuses on
arrest rates -- a factor which necessarily affects the ability of the criminal justice system to incapacitate. Spelman finds that as
offenders gain experience committing serious crimes, they learn to avoid being arrested by police. Police tend to learn to
identify experienced offenders, but their efforts are overwhelmed by the effects if offender learning.
Starting in Chapter 6, Spelman uses the data estimates derived in the previous chapters to begin making estimates of the
crime-reduction effects from incapacitation. He distinguishes between "collective incapacitation," (addressed in Chapter 6),
where the focus is on the crime-control effects, due to incapacitation, of the present criminal justice system, and "selective
incapacitation," (addressed in Chapter 7), where the focus is on efforts to increasingly target specific types of offenders. I might
add that nowhere is there a clear definition of the concept of collective incapacitation as used in the analysis, although it does
have to do with "...the likely crime-control effects of the present criminal justice system."(p. 197) The problem with this, of
course, is that the current system incorporates, to varying degrees, efforts to selectively incapacitate. This raises the question of
whether the implicit description of current practice as pursuing collective incapacitation has any real meaning.
There is little question that this book represents a significant contribution to the empirical literature on incapacitation. It is not,
however, without problems. For example, because the effort is oriented around secondary analysis of existing data from other
sources and studies, there is no consistent data base used throughout the study. This means that some of the estimates are
based on data from states, where a significant amount of the data come from California, Michigan, and Texas. Other data come
from studies of cities, especially Philadelphia, Washington, and New York. In some cases, data are available for a broader
array of states, and no explanation is given for why expanded analysis is conducted only on a particular handful of them. At one
point, data from a study conducted in London are presented without any explanation of why this might be pertinent to the
analysis of criminal incapacitation in the U.S.
Perhaps a more difficult issue has to do with the issue of drug-related crimes. Although Spelman's analysis incorporates analysis
of "drug sales" crimes, it is not at all clear that the analysis was able to fully capture either the challenge that drugs have created
for the justice system, or the potential for selectively incapacitating offenders who have committed crimes where drugs are
involved. Most practitioners, casual observers, and some scholars seem to believe that there has been something of a
fundamental change in the way that drugs influence criminal activity today, and that this change is of relatively recent vintage.
Initially, this raises the question whether only very recent data should be used to model crime-reduction effects of
incapacitation. The potential for selective incapacitation may not have been fully captured in this analysis because it was not able
to distinguish crimes where drugs played some role. A policy of selective incapacitation could very easily be formulated to
target offenders who commit robbery or burglary where there appears to be some involvement with drugs, such as crack
cocaine. Spelman's analysis sheds little light on the potential cost-effectiveness of such targeting. All this is to say that perhaps
selective incapacitation would be even more cost-effective than Spelman's analysis suggests.
All things considered, Spelman's work represents an impressive attempt to assemble what is known about incapacitation,
extending that knowledge to make it more generalizable. By assessing the quality of data relevant to incapacitation, and by
addressing the issues of uncertainties associated with these data, Spelman has done a service to scholars by providing a clear
picture of major areas where future analysis would be productive. Ultimately, the analysis should add a note of caution to any
policy maker who sees the indiscriminate pursuit of incapacitation goals as the answer to the crime problem in the U.S.
