It appears that John DiIulio's 1996 plea in the Journal of Economics Perspectives to attract economists to "help" with the analysis of criminal justice concerns has succeeded! In the past several years, economists have made substantial contributions to the study of trends in and causes of crime, the operation of criminal justice, and public policy. The contributions of economists to these fields have moved far beyond their traditional (narrow) role, which was analyzing crime as a time allocation problem and in trying to measure the aggregate effects of deterrence and/or the macro economy.

The study of crime and criminal justice is informed by the work of scholars and practitioners from a large number of fields, including criminology, sociology, psychology, and law. Economists have particular contributions to make due to our orientation toward understanding individual behavior, the aggregation of individual choices and actions, and disentangling causality. In this short essay I have tried to capture the breadth of the contributions by economists, but have had space to include only a few references to specific papers.

I. Criminal Behavior

In the 1960s and 1970s, theoretical work by economists drew attention to the motivation of offenders and the equilibrium crime rate as resulting from the choices of potential offenders, potential victims, and law enforcement. Over this same period, empirical work tried to tease out the causes of crime using aggregate data. These earlier efforts emphasized explanations that treated crime as an alternative to work in legal sector jobs, tempered by actors' responses to expected levels of punishment.

More recently, researchers have turned to models which incorporate more complex sets of interactions. These classes of models appear to have a better chance of explaining the wide variation in crime rates across location and time. It is not unusual for the crime rate to be 3 to 4 (or more) times higher in one large city than it is in another. Year-to-year increases and decreases in violent crime are often on the order of 20-25 percent. The variation in crime rates is substantially larger than the variation in, for example, demographics or economic conditions. Glaeser, Sacerdote, and Scheinkman (1996) modeled interactions among individuals within cities in an attempt to explain the large cross-sectional variation. Kennedy, Piehl, and Braga (1996) documented the retaliatory relationships among youth gangs in Boston and argued that these dynamics would lead to nonlinear returns to enforcement efforts. Levitt and Venkatesh (1998) analyzed the organization of a drug-selling gang. To the extent that criminal enterprises are organized with corporate-like structures or resemble a contagious process, the individual-level models will need to be abandoned or adapted.

II. The Operation of the Criminal Justice "System"

There were nearly 2 million prisoners in Federal or State correctional facilities or in local jails as of the end of 1998, with another 4 million adults on probation or parole. The sheer size of this population along with the seriousness of sanctions which restrict personal liberty require that the allocation of punishment to individuals receive serious study. Thus, how institutions operate, as well as how individuals within such institutions behave, are important lines of inquiry. Richard Posner has written several analyses of the courts, and a recent issue of the Journal of Law and Economics was dedicated to the consequences of the introduction in the 1980s of the Federal sentencing guidelines.

Recent reforms designed to reduce the discretion of judges may have moved discretion to earlier in the process. As a result, it is particularly important to understand how prosecutors decide to charge and proceed with cases. Papers such as Reinganum (1988) have modeled the plea bargaining process and the impact of restrictions on plea bargaining. Kessler and Piehl (1998) found that prosecutorial discretion was such that legislative sentencing reforms were applied more broadly than indicated by the language of the law. While there is a longer tradition of analyzing civil cases in the law and economics literature, issues such as selection of jurisdiction apply in both civil and criminal settings. There has been some recent evidence on the overall effectiveness of policing (Levitt 1997), but little in the economics literature on how the incentives operate within these or other investigative agencies.

III. Criminal Justice Policy

To an interested observer, it appears that criminal justice policy fluctuates a great deal over time. The rhetoric certainly does. One example of this is the shift from "rehabilitation" toward "punishment" in the way the role of corrections is discussed. Another is the relative absence of concerns about horizontal and vertical equity in discussions of sentencing policy in the 1990s (relative to the 1970s). Is criminal justice policy driven more by salient events or by changes in underlying conditions? How much do legislative changes at the state and federal level affect day-to-day operations? Do policies enacted in reaction to salient events have long-lasting, lingering effects? Kristin Butcher and I have several papers analyzing polices regarding the criminality of immigrants to the United States. In the mid-1990s, a number of wide-ranging laws were passed by Congress which, together, appear to be based on the notion that targeting immigrants would be a particularly effective way to reduce crime. Our analyses have yielded several results which are at odds with this conventional wisdom and furthermore found that there may be perverse effects (such as the increases in the deportability of criminal aliens may have led to increasing costs of incarcerating such offenders).

Although economists may not yet have a good model of the political economy of criminal justice policy, it appears that there continues to be room for us to contribute to understanding both the realities upon which policy ought to be based and the intended and unintended consequences of reforms.

References

Butcher, Kristin F. and Anne Morrison Piehl (forthcoming), "The Role of Deportation in the Incarceration of Immigrants," in George Borjas, ed., Issues in the Economics of Immigration, University of Chicago Press.

Butcher, Kristin F. and Anne Morrison Piehl (1998), "Recent Immigrants: Unexpected Implications for Crime and Incarceration," Industrial and Labor Relations Review, Vol. 51(4), p.654-679.

DiIulio, John J, Jr. (1996), "Help Wanted: Economists, Crime and Public Policy," Journal of Economic Perspectives, Vol. 10 (1), p.3:24.

Glaeser, Edward L, Bruce Sacerdote and Jose A. Scheinkman (1996), "Crime and Social Interactions," The Quarterly Journal of Economics, Vol. 111(2), p.507:48.

Kennedy, David M., Anthony A. Braga and Anne M. Piehl (1996), "Youth Violence in Boston: Gun Markets, Serious Youth Offenders, and a Use-Reduction Strategy," Law and Contemporary Problems, Vol. 59(1), p.147-183.

Kessler, Daniel P. and Anne Morrison Piehl (1998), "The Role of Discretion in the Criminal Justice System," Journal of Law, Economics, and Organization, Vol. 14(2), p.256-276.

Levitt, Steven D. (1997), "Using Electoral Cycles in Police Hiring to Estimate the Effect of Police on Crime," American Economic Review, Vol. 87 (3), p.270-90.

Levitt, Steven D. and Sudhir Alladi Venkatesh (1998), "An Economic Analysis of a Drug? Selling Gang's Finances," NBER Working Paper No. W6592.

Reinganum, Jennifer F. (1988), "Plea Bargaining and Prosecutorial Discretion," American Economic Review, Vol. 78(4), p.713:28.

Anne Morrison Piehl is Associate Professor of Public Policy, John F. Kennedy School of Government, Harvard University. Her research includes the study of violence among young people, criminal sentencing, the relationship between economic opportunity and criminal behavior, and criminal justice policy. She can be reached at anne_piehl@harvard.edu.