Published Research
Abstracts of articles on the deterrent effect of capital punishment. Our goal is to collect abstracts of studies published in reputable peer-reviewed journals in the last ten years, as well as working papers of studies submitted for such publication. We welcome suggestions for additions. Please e-mail Kent Scheidegger via our contact page.
Working Papers


Hashem Dezhbakhsh & Paul H. Rubin
From the 'econometrics of capital punishment' to the 'capital punishment' of econometrics: on the use and abuse of sensitivity analysis
Applied Economics, Vol. 43, Issue 25, pages 3655-3670 (2011)

Abstract:The academic debate over the deterrent effect of capital punishment has intensified again with a major policy outcome at stake. About two dozen empirical studies have recently emerged that explore the issue. Donohue and Wolfers (2005) claim to have examined the recent studies and shown the evidence not to be robust to specification changes. We argue that the narrow scope of their study does not warrant this claim. Moreover, focusing on our two studies that they have examined, we show the deterrence findings to be robust, while their work has serious flaws and their reporting appears to be selective. The selectivity is biased towards showing 'no deterrence'.

Dale O. Cloninger & Roberto Marchesini
Reflections on a critique
Applied Economics Letters, Vol. 16, No. 17, pages 1709 - 1711 (Nov. 2009)

Abstract: Critiques of scholarly research contain their own flaws; sometimes even more so than the work they are critiquing. Such is the case of the critique of our research authored by John Donohue and Jason Wolfers. Published in the Stanford Law Review their paper avoided the blind peer review process and consequently contains elements that undoubtedly would not have survived peer review. That possibility aside, we show that their alternative measures of criminal activity have no theoretical basis nor any empirical precedent within the modified portfolio approach employed in our research. Putting even that aside, we show that their empirical results are not inconsistent with ours. Thus, upon reflection, we see no justification to amend, modify or otherwise alter our methods or results.

Kenneth C. Land, Raymond H. C. Teske, Jr., & Hui Zheng
The Short-Term Effects of Executions on Homicides: Deterrence, Displacement, or Both?
Criminology, vol. 47, no. 4, pp. 1009-1043 (2009)

Abstract: Does the death penalty save lives? In recent years, a new round of research has been using annual time-series panel data from the 50 U.S. states for 25 or so years from the 1970s to the late 1990s that claims to find many lives saved through reductions in subsequent homicide rates after executions. This research, in turn, has produced a round of critiques, which concludes that these findings are not robust enough to model even small changes in specifications that yield dramatically different results. A principal reason for this sensitivity of the findings is that few state-years exist (about 1 percent of all state-years) in which six or more executions have occurred. To provide a different perspective, we focus on Texas, a state that has used the death penalty with sufficient frequency to make possible relatively stable estimates of the homicide response to executions. In addition, we narrow the observation intervals for recording executions and homicides from the annual calendar year to monthly intervals. Based on time-series analyses and independent-validation tests, our best-fitting model shows that, from January 1994 through December 2005, evidence exists of modest, short-term reductions in homicides in Texas in the first and fourth months that follow an execution—about 2.5 fewer homicides total. Another model suggests, however, that in addition to homicide reductions, some displacement of homicides may be possible from one month to another in the months after an execution, which reduces the total reduction in homicides after an execution to about .5 during a 12-month period. Implications for additional research and the need for future analysis and replication are discussed.

Paul R. Zimmerman
Statistical Variability and the Deterrent Effect of the Death Penalty
American Law and Economics Review, vol. 11, no. 2, pp. 370-398 (2009)

Abstract: In a recent paper Donohue and Wolfers (D&W) critique a number of modern econometric studies purporting to demonstrate a deterrent effect of capital punishment. This paper focuses on D&W's central criticism of a study by Zimmerman; specifically, that the estimated standard errors on the subset of his regressions that suggest a deterrent effect are downward biased due to autocorrelation. The method that D&W rely upon to adjust Zimmerman's standard errors is, however, potentially problematic, and is also only one of several methods to address the presence of autocorrelation. To this end, Zimmerman's original models are subjected to several parametric corrections for autocorrelation, all of which result in statistically significant estimates that are of the same magnitude to his original estimates. The paper also presents results obtained from an alternative model whose specification is motivated on theoretical and statistical grounds. These latter results also provide some evidence supporting a deterrent effect. Finally, the paper discusses D&W's use of randomization testing and their contention that executions are not carried out often enough to plausibly deter murders.

Michael Frakes & Matthew Harding
The Deterrent Effect of Death Penalty Eligibility: Evidence from the Adoption of Child Murder Eligibility Factors
American Law and Economics Review, vol. 11, no. 2, pp. 451-497 (2009)

Abstract: We draw on variations in the reach of capital punishment statutes between 1977 and 2004 to identify the deterrent effects associated with capital eligibility. Focusing on the most prevalent eligibility expansion, we estimate that the adoption of a child murder factor is associated with an approximately 20% reduction in the child murder rate. Eligibility expansions may enhance deterrence by (i) paving the way for more executions and (ii) providing prosecutors with greater leverage to secure enhanced noncapital sentences. While executions themselves are rare, this latter channel may be triggered fairly regularly, providing a reasonable basis for a general deterrent response.

Randi Hjalmarsson
Does Capital Punishment have a "Local" Deterrent Effect on Homicides?
American Law and Economics Review, vol. 11, no. 2, pp. 310-334 (2009)

Abstract: The vast majority of death penalty studies use geographically or temporally aggregated data. Such aggregation can make it virtually impossible to identify small amounts of variation in homicides due to executions. Therefore, this study uses data that are disaggregated down to daily and city levels to test whether executions have a short-term deterrent effect. Little consistent evidence is found that Texas executions deter Dallas, San Antonio, and Houston homicides from 1999 to 2004. The analysis also does not consistently support the hypotheses that the deterrent effect should be more evident for local executions or executions that received local media coverage.

John J. Donohue, III & Justin Wolfers
Estimating the Impact of the Death Penalty on Murder
American Law and Economics Review, vol. 11, no. 2, pp. 249-309 (2009)

Abstract: This paper reviews the econometric issues in efforts to estimate the impact of the death penalty on murder, focusing on six recent studies published since 2003. We highlight the large number of choices that must be made when specifying the various panel data models that have been used to address this question. There is little clarity about the knowledge potential murderers have concerning the risk of execution: are they influenced by the passage of a death penalty statute, the number of executions in a state, the proportion of murders in a state that leads to an execution, and details about the limited types of murders that are potentially susceptible to a sentence of death? If an execution rate is a viable proxy, should it be calculated using the ratio of last year's executions to last year's murders, last year's executions to the murders a number of years earlier, or some other values? We illustrate how sensitive various estimates are to these choices. Importantly, the most up-to-date OLS panel data studies generate no evidence of a deterrent effect, while three 2SLS studies purport to find such evidence. The 2SLS studies, none of which shows results that are robust to clustering their standard errors, are unconvincing because they all use a problematic structure based on poorly measured and theoretically inappropriate pseudo-probabilities that are designed to capture the key deterrence elements of a state's death penalty regime, and because their instruments are of dubious validity. We also discuss the appropriateness of the implicit assumption of the 2SLS studies that OLS estimates of the impact of the death penalty would be biased against a finding of deterrence.

Ethan Cohen-Cole, Steven Durlauf, Jeffrey Fagan, & Daniel Nagin
Model Uncertainty and the Deterrent Effect of Capital Punishment
American Law and Economics Review, vol. 11, no. 2, pp. 335-369 (2009)

Abstract: The reintroduction of capital punishment in 1976 that ended the four-year moratorium on executions generated by the Supreme Court in the 1972 decision Furman v. Georgia has permitted researchers to employ state-level heterogeneity in the use of capital punishment to study deterrent effects. However, no scholarly consensus exists as to their magnitude. A key reason that this has occurred is that the use of alternative models across studies produces differing estimates of the deterrent effect. Because differences across models are not well motivated by theory, the deterrence literature is plagued by model uncertainty. We argue that the analysis of deterrent effects should explicitly recognize the presence of model uncertainty in drawing inferences. We describe methods for addressing model uncertainty and apply them to understand the disparate findings between two major studies in the deterrence literature, finding that evidence of deterrent effects appears, while not nonexistent, weak.

Bijou Yang & David Lester
The deterrent effect of executions: A meta-analysis thirty years after Ehrlich
Journal of Criminal Justice, vol. 36, no. 5, pp. 453–460 (2008)

Abstract: In 1975, Ehrlich published a seminal paper in American Economic Review which argued that executions prevent murders in America. Subsequent empirical studies varied in their methodology and the time-period/region/country covered, and therefore it is difficult to draw a clear conclusion about the deterrent effect of executions. This article applies a meta-analysis to combine the results from refereed studies in order to summarize objectively the findings. The overall results of the meta-analysis supported the deterrent effect of executions, but the evidence for a deterrent effect depended on the type of study carried out (time-series and panel data versus cross-sectional data and the effects of publicity).

Charles N. W. Keckle
Life v. Death: Who Should Capital Punishment Marginally Deter?
Journal of Law, Economics and Policy, vol. 2, no. 1, pp. 101-161 (2006)

Abstract: Econometric measures of the effect of capital punishment have increasingly provided evidence that it deters homicides. However, most researchers on both sides of the death penalty debate continue to rely on rather simple assumptions about criminal behavior. I attempt to provide a more nuanced and predictive rational choice model of the incentives and disincentives to kill, with the aim of assessing to what extent the statistical findings of deterrence are in line with theoretical expectations. In particular, I examine whether it is plausible to suppose there is a marginal increase in deterrence created by increasing the penalty from life imprisonment without parole to capital punishment. The marginal deterrence effect is shown to be a direct negative function of prison conditions as they are anticipated by the potential offender – the more tolerable someone perceives imprisonment to be, the less deterrent effect prison will have, and the greater the amount of marginal deterrence the threat of capital punishment will add. I then examine the empirical basis for believing there to be a subset of killers who are relatively unafraid of the prison environment, and who therefore may be deterred effectively only by the death penalty. Criminals, empirically, appear to fear a capital sentence, and are willing to sacrifice important procedural rights during plea bargaining to avoid this risk. This has the additional effect of increasing the mean expected term of years attached to a murder conviction, and may generate a secondary deterrent effect of capital punishment. At least for some offenders, the death penalty should induce greater caution in their use of lethal violence, and the deterrent effect seen statistically is possibly derived from the change in the behavior of these individuals. This identification of a particular group on whom the death penalty has the greatest marginal effect naturally suggests reforms in sentencing (and plea bargaining) which focus expensive capital prosecutions on those most insensitive to alternative criminal sanctions.

Paul R. Zimmerman
Estimates of the Deterrent Effect of Alternative Execution Methods in the United States: 1978-2000
American Journal of Economics and Sociology, vol. 65, no. 4, p. 909 (Oct. 2006)

Abstract: Several recent econometric studies suggest that states' application of capital punishment deters the rate of murder [Brumm and Cloninger (1996), Cloninger and Marchesini (2001), Mocan and Gittings (2001), and Zimmerman (2002)]. Since the U.S. Supreme Court's moratorium on state executions was lifted in 1976, states with death penalty laws have executed individuals using one or more of five different methods of execution (electrocution, lethal injection, gas chamber asphyxiation, hanging, and/or firing squad). The perceived "brutality" of certain execution methods (such as electrocution and gas chamber asphyxiation) has also recently lead to lethal injection being imposed as the sole method of execution in several death penalty states.

Using a panel of state-level data over the years 1978-2000, this paper examines whether the method by which death penalty states conduct their executions affects the per-capita incidence of murder in a differential manner. Several measures of the subjective probability of being executed are developed taking into account the timing of individual executions as in Mocan and Gittings (2001). The empirical estimates suggest that the deterrent effect of capital punishment is driven primarily by executions conducted by electrocution. None of the other four methods of execution are found to have a statistically significant impact on the per-capita incidence of murder. These results are robust with respect to the manner in which the subjective probabilities of being executed are defined, whether or not a state has a death penalty law on the books, the removal of state and year fixed effects, controls for state-specific time trends, simultaneous control of all execution methods, and controls for other forms of public deterrence. In addition, it is shown that the negative and statistically significant impact of electrocutions is not driven by the occurrence of a "botched" electrocution execution during the relevant time period.

Paresh Narayan & Russell Smyth
Dead Man Walking: An Empirical Reassessment of the Deterrent Effect of Capital Punishment Using the Bounds Testing Approach to Cointegration
Applied Economics, vol. 38, no. 17, pp. 1975-1989 (Sept. 20, 2006)

Abstract: This paper empirically estimates a murder supply equation for the United States from 1965 to 2001 within a cointegration and error correction framework. Our findings suggest that any support for the deterrence hypothesis is sensitive to the inclusion of variables for the effect of guns and other crimes. In the long-run we find that real income and the conditional probability of receiving the death sentence are the main factors explaining variations in the homicide rate. In the short run the aggravated assault rate and robbery rate are the most important determinants of the homicide rate.

Hashem Dezhbakhsh & Joanna M. Shepherd
The Deterrent Effect of Capital Punishment: Evidence from a "Judicial Experiment"
Economic Enquiry, vol. 44, no. 3, pp. 512-535 (July 2006)

Abstract: We use panel data for 50 states during the 1960–2000 period to examine the deterrent effect of capital punishment, using the moratorium as a "judicial experiment." We compare murder rates immediately before and after changes in states' death penalty laws, drawing on cross-state variations in the timing and duration of the moratorium. The regression analysis supplementing the before-and-after comparisons disentangles the effect of lifting the moratorium on murder from the effect of actual executions on murder. Results suggest that capital punishment has a deterrent effect, and that executions have a distinct effect which compounds the deterrent effect of merely (re)instating the death penalty. The finding is robust across 96 regression models.

Richard Berk
New Claims about Execution and General Deterrence: Deja Vu All over Again?
Journal of Empirical Legal Studies, vol. 2, issue 2, pp. 303-330 (July 2005)

Abstract: A number of papers have recently appeared claiming to show that in the United States executions deter serious crime. There are many statistical problems with the data analyses reported. This article addresses the problem of "influence," which occurs when a very small and atypical fraction of the data dominate the statistical results. The number of executions by state and year is the key explanatory variable, and most states in most years execute no one. A very few states in particular years execute more than five individuals. Such values represent about 1 percent of the available observations. Reanalyses of the existing data are presented showing that claims of deterrence are a statistical artifact of this anomalous 1 percent.

Dale O. Cloninger & Roberto Marchesini
Execution Moratoriums, Commutations and Deterrence: the case of Illinois
Applied Economics, vol. 38, no. 9, pp. 967-973 (May 20, 2006)

Abstract: In an earlier work the impact of an execution moratorium in Texas on the monthly returns (first differences) of homicides was investigated. That moratorium was judicially imposed pending the appeal of a death sentence that could have had widespread consequences. A similar methodology is applied to the state of Illinois. In January 2000, the Governor of Illinois declared a moratorium on executions pending a review of the judicial process that condemned certain murderers to the death penalty. In January 2003 just prior to leaving office, the Governor commuted the death sentences of all of those who then occupied death row. It is found that these actions are coincident with the increased risk of homicide incurred by the residents of Illinois over the 48 month post-event period for which data were available. The increased risk produced an estimated 150 additional homicides during the post-event period.

Robert Weisberg
The Death Penalty Meets Social Science: Deterrence and Jury Behavior Under New Scrutiny
Annual Review of Law and Social Science, vol. 1, pp. 151-170 (December 2005)

Abstract: Social science has long played a role in examining the efficacy and fairness of the death penalty. Empirical studies of the deterrent effect of capital punishment were cited by the Supreme Court in its landmark cases in the 1970s; most notable was the 1975 Isaac Ehrlich study, which used multivariate regression analysis and purported to show a significant marginal deterrent effect over life imprisonment, but which was soon roundly criticized for methodological flaws. Decades later, new econometric studies have emerged, using panel data techniques, that report striking findings of marginal deterrence, even up to 18 lives saved per execution. Yet the cycle of debate continues, as these new studies face criticism for omitting key potential variables and for the potential distorting effect of one anomalously high-executing state (Texas). Meanwhile, other empiricists, relying mainly on survey questionnaires, have taken a fresh look at the human dynamics of death penalty trials, especially the attitudes and personal background factors that influence capital jurors.

Joanna M. Shepherd, Clemson University
>Murders of Passion, Execution Delays, and the Deterrence of Capital Punishment
Journal of Legal Studies, vol. 33, no. 2, pp. 283-322 (June 2004)

Abstract: I examine two important questions in the capital punishment literature: what kinds of murders are deterred and what effect the length of the death-row wait has on deterrence? To answer these questions, I analyze data unused in the capital punishment literature: monthly murder and execution data. Monthly data measure deterrence better than the annual data used in earlier capital punishment papers for two reasons: it is impossible to see monthly murder fluctuations in annual data and only monthly data allow a model in which criminals update their perceived execution risk frequently. Results from least squares and negative binomial estimations indicate that capital punishment does deter: each execution results in, on average, three fewer murders. In addition, capital punishment deters murders previously believed to be undeterrable: crimes of passion and murders by intimates. Moreover, murders of both black and white victims decrease after executions. This suggests that, even if the application of capital punishment is racist, the benefits of capital punishment are not. However, longer waits on death row before execution lessen the deterrence. Specifically, one less murder is committed for every 2.75-years reduction in death row waits. Thus, recent legislation to shorten the wait on death row should strengthen capital punishment's deterrent effect.

Paul R. Zimmerman
State Executions, Deterrence and the Incidence of Murder
Journal of Applied Economics, vol. 7, no. 1, pp. 163-193 (May 2004)

Abstract: This study employs a panel of U.S. state-level data over the years 1978-1997 to estimate the deterrent effect of capital punishment. Particular attention is paid to problems of endogeneity bias arising from the non-random assignment of death penalty laws across states and a simultaneous relationship between murders and the deterrence probabilities. The primary innovation of the analysis lies in the estimation of a simultaneous equations system whose identification is based upon the employment of instrumental variables motivated by the theory of public choice. The estimation results suggest that structural estimates of the deterrent effect of capital punishment are likely to be downward biased due to the influence of simultaneity. Correcting for simultaneity, the estimates imply that a state execution deters approximately fourteen murders per year on average. Finally, the results also suggest that the announcement effect of capital punishment, as opposed to the existence of a death penalty provision, is the mechanism actually driving the deterrent effect associated with state executions.

Zhiqiang Liu
Capital Punishment and the Deterrence Hypothesis: Some New Insights and Empirical Evidence
Eastern Economic Journal, vol. 30, iss. 2, p. 237 (Spring 2004)

Abstract: Economists have made repeated efforts through both theoretical modeling and empirical testing to understand the deterrent effect of capital punishment. By and large, they have found a negative and statistically significant effect of capital punishment on the act of murder (that is, the death penalty deters murder). Ehrlich [1975] provides the first systematic analysis of the relationship between capital punishment and murder along with the first empirical test of the deterrence hypothesis concerning not only capital punishment but also other deterrent measures. His results suggest that on the average eight murder victims might have been saved as a result of one execution for the sample period 1933-67 in the United States. Although Ehrlich's work was criticized by scholars such as Waldo [1981] and Forst [1983], many subsequent studies, using independent time-series and cross-section data from the United States [Ehrlich, 1977; Layson, 1985; Cloninger, 1992; Ehrlich and Liu, 1999; Dezhbakhsh, et al. 2000], Canada [Layson, 1983] and the UK [Wolpin, 1978], have offered corroborating evidence consistent with the deterrence hypothesis.

H. Naci Mocan & R. Kaj Gittings
Getting Off Death Row: Commuted Sentences and the Deterrent Effect of Capital Punishment
Journal of Law and Economics, vol. 46, no. 2, pp. 453-478 (October 2003)

Abstract:  This paper merges a state-level panel data set that includes crime and deterrence measures and state characteristics with information on all death sentences handed out in the United States between 1977 and 1997. Because the exact month and year of each execution and removal from death row can be identified, they are matched with state-level criminal activity in the relevant time frame. Controlling for a variety of state characteristics, the paper investigates the impact of the execution rate, commutation and removal rates, homicide arrest rate, sentencing rate, imprisonment rate, and prison death rate on the rate of homicide. The results show that each additional execution decreases homicides by about five, and each additional commutation increases homicides by the same amount, while an additional removal from death row generates one additional murder. Executions, commutations, and removals have no impact on robberies, burglaries, assaults, or motor-vehicle thefts.

Hashem Dezhbakhsh, Paul H. Rubin, & Joanna M. Shepherd
Department of Economics, Emory University
Does Capital Punishment Have a Deterrent Effect? New Evidence from Postmoratorium Panel Data

American Law & Economics Review, vol. 5, no. 2, pp. 344-376 (Fall 2003)

Abstract:  Evidence on the deterrent effect of capital punishment is important for many states that are currently reconsidering their position on the issue.  We examine the deterrent hypothesis using county-level, post-moratorium panel data and a system of simultaneous equations.  The procedure we employ overcomes common aggregation problems, eliminates the bias arising  from unobserved heterogeneity, and provides evidence relevant for current conditions.  Our results suggest that capital punishment has a strong deterrent effect; each execution results, on average, in 18 fewer murders—with a margin of error of plus or minus 10.  Tests show that results are not driven by tougher sentencing laws, and are also robust to many alternative specifications.

Lawrence Katz, Steven D. Levitt & Ellen Shustorovich
Prison Conditions, Capital Punishment, and Deterrence
American Law and Economics Review, vol. 5, issue 2, pages 318-343 (Fall 2003)

Abstract: Previous research has attempted to identify a deterrent effect of capital punishment. We argue that the quality of life in prison is likely to have a greater impact on criminal behavior than the death penalty. Using state-level panel data covering the period 1950--90, we demonstrate that the death rate among prisoners (the best available proxy for prison conditions) is negatively correlated with crime rates, consistent with deterrence. This finding is shown to be quite robust. In contrast, there is little systematic evidence that the execution rate influences crime rates in this time period.

James A. Yunker, Western Illinois University
A New Statistical Analysis of Capital Punishment Incorporating U.S. Postmoratorium Data
Social Science Quarterly, vol. 82, no. 2, pp. 297-311 (2002)

Objective:  This article reports on a basic regression analysis of the deterrence hypothesis incorporating U.S. data that has accumulated since the resumption of capital punishment in 1977.  Methods.  The cross-sectional approach employs data on state homicide rates and estimated execution rates between 1976 and 1997 across 50 states and the District of Columbia.  The time series approach employs annual data on the U.S. national homicide rate and estimated national execution rate between 1930 and 1997.  Results.  Using state data, statistically weak support is found for the deterrence hypothesis.  Using national time series data, considerably stronger statistical support is found for the deterence hypothesis.  It is also shown that the same time series regression using data from 1930 to 1976 does not support the deterrence hypothesis, thus showing the probative value of the more recent data.  Conclusions.  Statistical data from the postmoratorium period are likely to be useful in evaluating the deterrence hypothesis, and therefore social scientists should be carefully examining this evidence.

Dale O. Cloninger & Roberto Marchesini
Execution and Deterrence: A Quasicontrolled Group Experiment
Applied Economics, vol. 33, no. 5, pp. 569-576 (2001)

Abstract: Using portfolio analysis in a type of controlled group experiment, this study develops an empirical model of homicide changes in Texas over a period of a "normal" number of executions. The empirically derived model then estimates the changes in the number of homicides in Texas (1) over a period of near zero executions and; (2) over an immediate subsequent period of double the "normal" number of executions. The actual changes in Texas homicides over the first period is less than estimated by the model and greater (or no different) than estimated by the model in the second period. Because changes in the number of homicides in Texas and throughout the United States were negative over both periods, these empirical results are consistent with the deterrence hypothesis. That is, there were a greater than predicted number of homicides in the first period and fewer than predicted number in the second period.

Jon Sorensen, Robert Wrinkle, Victoria Brewer, & James Marquart
Capital punishment and deterrence:  Examining the effect of executions on murder in Texas
Crime and Delinquency, vol. 45, no.4, pp. 481-493 (Oct. 1999)

Abstract:  This study tested the deterrence hypothesis in Texas, the most active execution jurisdication during the modern era.

Isaac Ehrlich and Zhiqiang Liu
Sensitivity Analysis of the Deterrence Hypothesis:  Lets Keep the Econ in Econometrics
Journal of Law and Economics, vol. 42, no. 1, pp. 455-487 (April 1999)

Abstract:  Leamer and McManus applied Extreme Bound Analysis (EBA) in an empirical study of the deterrent effects of capital punishment and other penalties. Their analysis has questioned the validity of the deterrence hypothesis. The thrust of our paper is twofold: first, by applying EBA to well-known econometric models of demand, production, and human-capital investment, our analysis exposes and illustrates the inherent flaws of EBA as a method of deriving valid inferences about model specification. Second, since the analysis shows Leamer and McManus's inferences about deterrence to be based on a flawed methodology, we offer an alternative, theory-based sensitivity analysis of estimated deterrent effects using similar data. Our analysis supports the deterrence hypothesis. More generally, it emphasizes the indispensable role of theory in guiding sensitivity analyses of model specification.

Harold J. Brumm and Dale O. Cloninger
Perceived Risk of Punishment and the Commission of Homicides:  A Covariance Structure Analysis
Journal of Economic Behavior and Organization, vol. 31, no. 1, pp. 1-11 (Sept. 1996)
After clicking the link, choose "volumes 31-40," then "volume 31, issue 1", finally click on "abstract."

Abstract:  If the behavior of potential murderers does in fact respond to the risk of punishment, it is the perceived risk rather than the ex post risk as measured by arrest rates, conviction rates, or execution rates. Previous empirical studies of homicide behavior have, by and large, ignored this distinction. The present paper accommodates this distinction by estimating a covariance structure model in which the perceived risk is treated as an endogenous latent variable, with two measures of sanctions as its indicators. Cross-section data are used for the estimation. One of the principal findings is that the homicide commission rate is significantly and negatively correlated with the perceived risk of punishment, which provides empirical support for the deterrence hypothesis (Ehrlich, 1975). The other principal findings are that the perceived risk of punishment is (a) significantly and negatively correlated with the homicide commission rate, and (b) significantly and positively correlated with police presence. The latter results provide empirical support for the resource saturation hypothesis (Fisher and Nagin, 1978).


Naci H. Mocan & R. Kaj Gittings
The Impact of Incentives on Human Behavior: Can We Make It Disappear? The Case of the Death Penalty (October 2006)
NBER Working Paper No. 12631

Abstract: Although decades of empirical research has demonstrated that criminal behavior responds to incentives, non-economists frequently express the belief that human beings are not rational enough to make calculated decisions about the costs and benefits of engaging in crime and therefore, a priori drawing the conclusion that criminal activity cannot be altered by incentives. However, scientific research should not be driven by personal beliefs. Whether or not economic conditions matter or deterrence measures such police, arrests, prison deaths, executions, and commutations provide signals to people is an empirical question, which should be guided by a solid theoretical framework. In this paper we extend the analysis of Mocan and Gittings (2003). We alter the original model in a number of directions to make the relationship between homicide rates and death penalty related outcomes (executions, commutations and removals) disappear. We deliberately deviate from the theoretically consistent measurement of the risk variables originally employed by Mocan and Gittings (2003) in a variety of ways. We also investigate the sensitivity of the results to changes in the estimation sample (removing high executing states for example) and weighting. The basic results are insensitive to these and a variety of other specification tests performed in the paper. The results are often strong enough to even hold up under theoretically meaningless measurements of the risk variables. In summary, the original findings of Mocan and Gittings (2003) are robust, providing evidence that people indeed react to incentives induced by capital punishment. Research findings about the deterrent effect of the death penalty evoke strong feelings, which could be due to political, ideological, religious, or other personal beliefs. Yet, such findings do not mean that capital punishment is good or bad, nor does it provide any judgment about whether capital punishment should be implemented or abolished. It is simply a scientific finding which demonstrates that people react to incentives. Therefore, there is no need to be afraid of this result.

Paul R. Zimmerman
On the Uses and 'Abuses' of Empirical Evidence in the Death Penalty Debate (November 2006)

Abstract: John J. Donohue and Justin Wolfers [Uses and Abuses of Empirical Evidence in the Death Penalty Debate, Stanford Law Review, vol. 58 (2005): 791-846] critique a number of recent econometric studies purporting to demonstrate a deterrent effect of capital punishment. Donohue and Wolfers argue that the conclusions drawn from most of these studies are fundamentally flawed as their results are highly sensitive to small changes in the employed econometric specification. This paper focuses on Donohue's and Wolfers' criticism of a study by Paul R. Zimmerman [State Executions, Deterrence, and the Incidence of Murder, Journal of Applied Economics, vol. 7 (2004): 163-193]. It is shown that Donohue and Wolfers make a number of misrepresentations and errors in assessing the results and conclusions put forward in Zimmerman's analysis, and as such, their criticisms of the latter are effectively vacuous. And although Zimmerman's ultimate conclusions regarding the deterrent effect of capital punishment are not fundamentally different from Donohue's and Wolfers', the latter authors' comprehensive review of recent death penalty studies (as well as their admonishments concerning the use of potentially fragile empirical models to inform policy decisions) marks their paper as an important contribution to the literature.

John R. Lott, Jr. and William M. Landes
Multiple Victim Public Shootings, Bombings, and Right-to-Carry Concealed Handgun Laws:  Contrasting Private and Public Law Enforcement
University of Chicago Law School, John M. Olin Law and Economics Working Paper No. 73 (2002),
Link to earlier version of the working paper:

Abstract:  Few events obtain the same instant worldwide news coverage as multiple victim public shootings. These crimes allow us to study the alternative methods used to kill a large number of people (e.g., shootings versus bombings), marginal deterrence and the severity of the crime, substitutability of penalties, private versus public methods of deterrence and incapacitation, and whether attacks produce "copycats." Yet, economists have not studied this phenomenon. Our results are surprising and dramatic. While arrest or conviction rates and the death penalty reduce "normal" murder rates, our results find that the only policy factor to influence multiple victim public shootings is the passage of concealed handgun laws. We explain why public shootings are more sensitive than other violent crimes to concealed handguns, why the laws reduce both the number of shootings as well as their severity, and why other penalties like executions have differential deterrent effects depending upon the type of murder.


The following articles discuss the philosophical and policy implications of deterrence and capital punishment. Because they do not claim to be empirical research, the criterion of peer-reviewed publication does not apply.

Cass R. Sunstein & Adrian Vermeule
Is Capital Punishment Morally Required? The Relevance of Life-Life Tradeoffs
58 Stan. L. Rev. 703 (Jan. 2006)

Abstract: Many people believe that the death penalty should be abolished even if, as recent evidence seems to suggest, it has a significant deterrent effect. But if such an effect can be established, capital punishment requires a life-life tradeoff, and a serious commitment to the sanctity of human life may well compel, rather than forbid, that form of punishment. The familiar problems with capital punishment— potential error, irreversibility, arbitrariness, and racial skew—do not require abolition because the realm of homicide suffers from those same problems in even more acute form. Moral objections to the death penalty frequently depend on a sharp distinction between acts and omissions, but that distinction is misleading in this context because government is a special kind of moral agent. The widespread failure to appreciate the life-life tradeoffs potentially involved in capital punishment may depend in part on cognitive processes that fail to treat “statistical lives” with the seriousness that they deserve. The objection to the act/omission distinction, as applied to government, has implications for many questions in civil and criminal law.

Carol S. Steiker
No, Capital Punishment is Not Morally Required: Deterrence, Deontology, and the Death Penalty
58 Stan. L. Rev. 751 (Jan. 2006)

Cass Sunstein and Adrian Vermeule argue that, if recent empirical studies finding that capital punishment has a substantial deterrent effect are valid, consequentialists and deontologists alike should conclude that capital punishment is not merely morally permissible but actually morally required. While the empirical studies are highly suspect (as John Donohue and Justin Wolfers elaborate in a separate article in this Issue), this Article directly critiques Sunstein and Vermeule’s moral argument. Acknowledging that the government has special moral duties does not render inadequately deterred private murders the moral equivalent of government executions. Rather, executions constitute a distinctive moral wrong (purposeful as opposed to nonpurposeful killing) and a distinctive kind of injustice (unjustified punishment). Moreover, acceptance of “threshold” deontology in no way requires a commitment to capital punishment even if substantial deterrence is proven. Rather, arguments about catastrophic “thresholds” face special challenges in the context of criminal punishment. This Article also explains how Sunstein and Vermeule’s argument necessarily commits us to accepting other brutal or disproportionate punishments and concludes by suggesting that even consequentialists should not be convinced by the argument.

Cass R. Sunstein & Adrian Vermeule
Deterring Murder: A Reply
58 Stan. L. Rev. 847 (Dec. 2005)

No abstract.