Marginal deterrence and multiple murders.

• Author: Ekelund, Robert B., Jr.

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One must calculate a penalty in terms not of the crime, but of its possible repetition. One must take into account not the past offence, but the future disorder. Things must be so arranged that the malefactor can have neither any desire to repeat his offence, nor any possibility of having imitators. Punishment, then, will be an art of effects....

Michel Foucault (1977, p. 93)

1. Introduction

   Study of the deterrent effect of capital punishment has become a staple of the economic literature emphasizing marginal behavior. The preponderance but not the totality (Fox and Radelet 1989; Fagan 2005) of empirical evidence in this ever-growing literature is that higher arrest, sentencing, and execution probabilities--marginal deterrence--all lower the murder rate (Mocan and Gittings 2003; Zhiqiang 2004; Zimmerman 2004). In a well-executed empirical study using county-level data, Dezhbakhsh, Rubin, and Shepherd (2004) show that between 1977 and 1996, higher arrest, sentencing, and execution probabilities all lower the murder rate (18 fewer murders, with the margin of error at plus or minus 10). (1) Shepherd (2004) shows, moreover, that even "domestic" homicides and other "crimes of passion" may be deterred. Less studied has been the effects of execution methods on murder rates, although Zimmerman (2003) has shown that executions conducted through electrocution have a significant effect on deterrence using state-level data between 1978 and 2000. But one critical issue remains: Does capital punishment deter all kinds of murder? Specifically, given the principles of marginal behavior and deterrence at the margin, does capital punishment deter multiple murders?

   The purpose of this paper is empirically to apply the concept of marginal deterrence to the effects of executions on multiple murders using state-level data between 1995 and 1999. We find, using data in part provided by the Federal Bureau of Investigation, that multiple murders are not deterred by execution in any form, quite possibly because the marginal cost of murders after the first is approximately zero. Although our research does not aim to cover old ground, we provide, in the course of our investigation and for purposes of comparison to multiple murders, additional empirical evidence on the effects of execution and method of execution on murder rates. (Our results here generally conform to the conclusions found in the extant and growing literature.)

   In an initial section we offer a brief history of the economics of deterrence and capital punishment and establish a hypothesis relating to marginal deterrence and multiple murders. In the following two sections we present empirical tests related to single murder, forms of punishment, and multiple murder. We include a discussion of the use of marginal deterrence in an attempt to ameliorate particular forms of multiple murder. Finally, we speculate on how or whether, in a contemporary social and political environment, extensions of marginal deterrence would be possible for homicides in general and multiple murders specifically that are now punishable by a less costly death penalty.

2. Murder and Marginal Deterrence: A Brief History

   The practice if not the theory of deterrence of all kinds of criminal acts is, of course, ancient. All societies have sought to restrict and punish rampant murder with a lowering of benefits and an increase in costs to perpetrators. All manner of "costs" accompanied the crime of murder during ancient and medieval times both under private systems of justice (e.g., the Germanic and early Anglo-Saxon frankpledge system) and under public systems, such as in those found in later Anglo-Saxon jurisprudence and continental systems. This history is bloody--to modern eyes "uncivilized"--and, in the case of the medieval Inquisitions, as we will see, creative in its applications of marginal deterrence.

   The modern economic conception of crime and punishment undoubtedly originated in substantive form with the "incentives-based" utilitarian philosophy of Jeremy Bentham (1931) and his brilliant secretary Edwin Chadwick (1800-1890). In two seminal essays Chadwick developed what we now call the economic theory of crime (1829), an incentives-based reform of the criminal justice system (1841). (2) Chadwick focused on economic crime--robberies--and developed an institutional analysis of factors that would restructure marginal incentives of perpetrators (thieves) as summarized in the following general relationships:

   [Marginal Cost.sub.Criminal Acts] = [Marginal Benefits.sub.Criminal Acts]

   or

   [Marginal Benefits.sub.Property Crimes] = Prob.(Apprehension) x (Cost from Apprehension) + Prob.(Conviction [Apprehension) x (Cost from Conviction) + Prob.(Punishment [including severity] [Conviction) x (Cost from Punishment).

   The marginal calculation is instantly recognizable as the one underlying the modern (Becker 1968) "economics of crime" discussed in the introduction above. (3) More to the point of the present study, Chadwick appeared to recognize that these principles also applied to murder and capital punishment. Capital punishment in England, immediately before Bentham's and Chadwick's time, had an extremely bad reputation in the populace because death sentences were not geared to marginal deterrence and were imposed for far lesser crimes than murder (Zaller 1987). (4) For example, novelist-criminologist Henry Fielding was an unabashed defender of capital punishment. In 1749 Fielding supported the execution of one Bosavern Penlez, a British sailor, who had caused a riot in a house of prostitution. Despite pleas from the jury that convicted him and from the public at large, he received the ultimate punishment, and Fielding (1749) wrote a spirited defense of the sentence. Capital punishment for "crimes" such as petty theft and "riots" in whorehouses had been eliminated by the time of Chadwick's evaluation of the criminal justice system. Thus, although he did not focus on the link between severity of punishment, that is, death, and deterrence in cases of murder, Chadwick clearly recognized such possibilities and tradeoffs among apprehension, conviction, and punishment. (5)

   The "economics" of crime thus established in the nineteenth century was reincarnated in modern economic theory in the second half of the twentieth century. (6) Although the seminal modern contribution was that of Gary Becker (1968), an important elaboration of the idea was made by George Stigler several years later (1970). Specifically, Stigler emphasizes the necessity for "optimal" marginal deterrence. In this situation, ill-established penalties would not have a deterrence effect. As Stigler argues, "... the marginal deterrence of heavy punishments could be very small or even negative ... if [for example] the offender will be executed for a minor assault and for a murder" (1970, p. 527). If an eye is to be plucked out or a foot chopped off for stealing $5 or $5 million, a thief might as well opt for the higher payoff. Thus, the establishment of marginal costs is necessary to marginal deterrence, or, in Stigler's words, "The penalties and chances of detection and punishment must be increasing functions of the enormity of the offense" (1970, p. 530). (7)

   That the marginal severity of punishment applied to property and other crimes is a deterrent is empirically verifiable. The existence of two--and three-strike laws of California, where the laws are seriously enforced, are a case in point. In a county-level study of the full deterrence effect of this legislation, Joanna M. Shepherd (2002a) studied the impact of these laws on all offenders (not simply those committing their last strike). Empirically she finds that, because strike laws may deter individuals contemplating committing their first offense, approximately 8 murders, 3,952 aggravated assaults, 10,672 robberies, and 384,488 burglaries were deterred in California over the first two years of the legislation. Set against this benefit was the substitution of larceny and auto theft (nonstrike offenses). (8) Numerous other studies (e.g., Trumbull 1989; Marvell and Moody 1995; Shepherd 2002b) would also appear to firmly establish the effectiveness of marginal deterrence in other forms of legislation and penalty structures as well. (9)

   The Nature of Murder and Marginal Deterrence

   The issue of the impact of marginal deterrence for murder, for some rather obvious reasons, has not been studied very extensively. There are numerous objections to the argument that murder would respond at all to forms or margins of punishment. For example, many criminologists and sociologists might be willing to grant that property crimes might respond to economic incentives but object stridently to the fact that homicide might react similarly. We argue that although some murders might be categorized as "acts of (irrational) passion," a number, perhaps a large number, of them might be analyzed as calculated and rational. Consider these briefly.

   Some murders are clearly calculated. Murders are demanded and supplied in our economy just as are drugs and sex. Like the property criminal, the killer is a middleman who steals the life of the victim and sells it to the murder contractor. Further, such crimes respond to traditional economic theory: Higher costs in the form of higher probabilities of detection, conviction, or execution will reduce "supply," causing a price increase and a reduction in the quantity demanded of murders for hire.

   Other murders, those so often cited in the sociological literature, are the so-called "crimes of passion." Without rational calculation, or so the story goes, capital punishment (or other forms of deterrence) could not elicit a rational response. As a matter of analysis and "law," culpability is reduced without advance deliberation and planning. But, economically, the absence of advance de liberation and planning does not mean that price is irrelevant. So-called "crimes...