Paul H. Rubin, Reply to Donohue and Wolfers on the Death Penalty and
Deterrence, Economists’ Voice 3, article 4 (Apr. 2006), available at
http://www.bepress.com/ev/vol3/iss5/art4/.
My response to Rep. Stam was long and detailed: It read:
Hi again Rep. Stam
Thanks for taking the time to read this long message.
Also, many thanks again for sending along the summary of deterrence studies. I have indeed read them and incorporated them into my book.
What I did is ask the experts (scholars who study the death penalty for a living) whether they think the death penalty works, as well as whether it is plagued by sserious problems. With regard to deterrence, this is the result:
"Does capital punishment, as actually practiced in the United States, achieve deterrence (i.e., prevent future murders by causing fear in would-be murderers so that they do not commit murder)?"
Yes 9%
No 79%
Unsure 12%
Three of four of those who said yes explained that the death penalty may provide a deterrent effect but that it was small and countered by the brutalization effect of executions. Most criminologists were adamant that the death penalty does not deter.
For each question I asked the experts I followed it up with a "fact check" section. The purpose of this section was to verify or refute what the experts said by reviewing the empirical evidence.
Here is the fact check section on deterrence (importantly, you'll note that the near consensus is that the recetnt "pro-deterrence" studies by economists, which run counter to decades and decades of research, are
fundamnetally flawed ... subject to replication the results were not supported and in some cases reversed):
The numbers in the fact check are footnotes, which I have pasted at the end of the message. The following is right from my new book "Death Nation: The Experts Explain American Capital Punishment."
"Fact Check.
Deterrence is logical and underlies most forms of criminal punishment. When we punish pets for peeing on the floor and scratching up the furniture, we do it so the animals will not do it again (prevention). We assume pets learn through punishment, as do people. This is why there is a huge market in the name of child discipline – there are literally hundreds of approaches to disciplining children, the majority of which likely rest on the deterrence hypothesis.
"When it comes to humans, we assume that people are hedonistic (pleasure-seeking), rational (can think in advance of behavior), that they want to avoid pain such as punishment, and thus the thought of punishment should deter wrongful behavior. Further, seeing punishment administered to others should also deter. Of course, all of this assumes people who murder are rational and that murder is a rational act.
"The vast majority of the available scientific evidence with regard to general deterrence suggests that the death penalty is not a deterrent to murder and cannot be for the simple reason that the most important element of punishment is missing – certainty.[28] Punishment must be certain in order to deter. As explained by deterrence experts William
Bailey and Ruth Peterson, the death penalty '[c]annot be expected to be an effective deterrent to murder if its level of certainty is zero or very slight.' They continue: 'Similarly, even if administered with a high level of certainty, capital punishment will not be effective in discouraging crime if it is administered secretly. Rather, deterrence is a communication theory, and it is the perceived severity, certainty, and celerity of punishment that result from sanctioning practices that are predicted to influence offense rates.[29]
"In the United States, the administration of the death penalty is so rarely applied and so unlikely to be applied to any individual – that the likelihood that the death penalty is a general deterrent is extremely small. As noted earlier, less than 5% of aggravated murderers and less than 1% of all killers is actually executed, and even when executions occur, they are carried out secretly in the middle of the night.
"Deterrence studies tend to compare states with the death penalty and without, nations with the death penalty and without, changes in crime rates in jurisdictions before and after having death penalty, the effects of highly publicized executions, and relationships between executions and the murder rate, controlling for other factors.[30] All of these studies lead to conclusions inconsistent with the deterrence hypothesis.
"One example of this kind of research is a group of studies by the late capital punishment scholar Thorsten Sellin examining murder rates in 'five groups of three contiguous states: three groups in the Mid-West, and two in New England.' The states were similar across many important variables but differed in that some had the death penalty and some did not. The results showed no evidence that the presence of the death penalty had any effect on murder rate differentials during the years 1940 to 1955, and '[a] later review of such comparisons carried out between 1919 and 1969 showed that, in the majority of cases, abolitionist states had lower rates of homicide than their retentionist neighbors and that states that abolished the death penalty generally tended to have a smaller increase in homicides than did retentionist neighboring states.'[31] More recent replications, correcting for some of the original studies’ weaknesses, found the same results through 1995, that generally there is little to no evidence of deterrence.[32]
"According to the evidence, murder rates are lower in states without the death penalty than those with it and lower in nations without the death penalty than with it.[33] Additionally, when states and nations abolish capital punishment or simply stop carrying out executions, the murder rate generally falls.[34] Highly publicized executions tend not to have
any effect on murder rates.[35] And empirical studies, properly conducted, rarely find a deterrent effect of executions on murder rates, as I will show below. This includes in studies of the effects of executions on murder within states and across states, and regardless of the type of murder examined.[36]
"The largest, most sophisticated study of murder rates from 1935 to 1969 which did find evidence of deterrence concluded that for each execution, eight murders would be prevented.[37] However, this study was replicated numerous times and no effect was found.[38] The study was plagued by numerous flaws, including the fact that when the years 1963 to 1969 were removed from the analysis, no deterrent effect was found.[39] Bailey and Peterson thus ask: “Why was the death penalty not a significant deterrent to murder from 1933 through the mid 1960s although capital punishment was a significant deterrent from the period 1933-69? What could have happened during the latter half of the 1960s to so radically change the truth of he matter?”[40] The National Academy of Sciences did not accept Ehrlich’s findings. Its 1978 report concluded that 'the real contribution to the strength of Ehrlich’s statistical findings lies in the simple graph of the upsurge of the homicide rate after 1962, coupled with the fall in the execution rate in the same period.'[41]
"Although there have not been many, most studies from the modern execution period have found no evidence consistent with the deterrence hypothesis.[42] After a review of 60 deterrence studies, Bailey and Peterson note: 'The available evidence remains ‘clear and abundant’ that, as practiced in the United States, capital punishment is not more
effective than imprisonment in deterring murder.'[43]
"In spite of this, some death penalty defenders maintain that the evidence does not disprove deterrence either. For example, philosopher Lois Pojman notes '… we must conclude that we lack strong statistical evidence that capital punishment deters … There is no such evidence for nondeterrence either. The statistics available are simply inconclusive ...'[44] Similarly, the late legal scholar, Ernest van den Haag, wrote: 'Statistics have not proved conclusively that the death penalty does or does not deter murder more than other penalties.'[45] Interestingly, in another work, Pojman concludes that 'while we cannot prove conclusively that the death penalty deters, the weight of evidence supports its deterrence. Furthermore, I think there are too many variables to hold constant for us to prove via statistics the deterrence hypothesis, and even if the requisite statistics were available, we could question whether they were cases of mere correlation versus causation.'[46]
"Supporters also point to the 'best bet hypothesis,' which says that if we do not know if the death penalty is a deterrent, we should bet that it is.[47] It asserts that it would be better to assume there is a deterrent (when there is not) and use the death penalty (because this only unnecessarily kills guilty murderers), than to assume there is not a deterrent (when there is) and not use the death penalty (because this allows innocent people to die). Following this logic, executions become a moral imperative.[48]
"Supporters also put forth anecdotal evidence of individuals who say they were deterred because of the death penalty. Stories do exist of those who claim to have been deterred by fear of capital punishment.[49]
"Some of the most recent studies do support a general deterrent effect of executions.[50] These studies, using various methodologies and data sets, find each execution results in three fewer murders,[51] five fewer homicides,[52] between three and 25 fewer murders with an average of 14,[53] between 8-28 murders with an average of 18,[54] and even 150
fewer murders.[55]
"The author of one of the studies finding a deterrent effect of capital punishment testified to Congress that the research has led to a 'strong consensus among economists that capital punishment deters crime' and concluded that 'studies are unanimous.' When questioned about research that ran counter to her conclusion, she replied: 'There may be people on
the other side that rely on older papers and studies that use outdated statistical techniques or older data, but all of the modern economic studies in the past decade have found a deterrent effect. So I am not sure what the other people are relying on.'[56]
"This research, some of which has not been published in peer-reviewed journals or replicated, offers findings that are inconsistent with the great breadth and depth of knowledge on this topic. The studies are thus viewed with great skepticism by capital punishment experts, including those in this study and those in the previous study of presidents of major criminological organizations, discussed in Chapter 3.
"A few authors claim the findings of the recent studies that support deterrence are flawed.[57] For example, Richard Berk claims that statistical problems with data analyses reported in the pro-deterrence studies explain the findings.[58] One example is that state-specific measures of executions are extremely skewed; Texas executed 336 people from 1977 to 2004, versus 94 executions in the next highest state of Virginia. Only ten other states executed more than twenty people since 1977 while 20 states executed none.[59] This means that some findings of deterrence may rest on effects from one or two states.[60]
"More importantly, professors John Donohue and Justin Wolfers, who examined recent studies finding deterrent effects of the death penalty, point out several very significant problems with the studies. Among the many problems with the pro-deterrence studies include failing to control key (and also unknown) variables leading to spurious findings,
confounding the effects of capital punishment with broader trends in society, failing to use rates of executions to control for population size in states, failing to consider the effects of imprisonment on crime rates, presenting results that are inconsistent with the regression models actually run, relying on measures of key variables generated by
scholars with clear ideological biases, using invalid instruments,[61] reporting faulty confidence intervals,[62] and reporting biases caused by inappropriate treatment of standard errors. When Donohue and Wolfers changed one single key variable dealing with citizen partisanship, it actually changed the direction of the findings from the original study, meaning that executions not only did not deter homicides but actually increased them.[63] They thus conclude 'one has little reason to prefer the conclusion that the death penalty will save lives to the conclusion that scores will die as a result of each execution.'[64]
"Further, 'the existing evidence for deterrence is surprisingly fragile' and 'extremely sensitive to very small changes in econometric specifications.'[65] Their own 'reanalysis shows that small changes in specifications, samples, or functional form can dramatically change the results. Indeed, several of the more expansive specifications point to
an antideterrent effect of the death penalty.'[66]
"Donohue and Wolfers write:
'We are led to conclude that there exists profound uncertainty about the deterrent (or antideterrent) effect of the death penalty; the data tell us that capital punishment is not a major influence on homicide rates, but beyond this, they do not speak clearly. Further, we suspect that our conclusion that econometric studies are highly uncertain about the
effects of the death penalty will persist for the foreseeable future ... Aggregating over all of our estimates, it is entirely unclear even whether the preponderance of evidence suggests that the death penalty causes more or less murder.'[67]
"Rather than relying on flawed methodological approaches to studying deterrence, Wolfers and Donohue authors assert that scholars should first determine if the real-world evidence is consistent with deterrence. Thus, they examine fluctuations in homicide rates and executions over decades. This leads to the following conclusion:
'No clear correlation between homicides and executions emerges from this long time series. In the first decade of the twentieth century, execution and homicide rates seemed roughly uncorrelated, followed by a decade of divergence as executions fell sharply and homicides trended up. Then for the next forty years, execution and homicides rates again tended to move together – first rising together during the 1920s and 1930s, and then falling together in the 1940s and 1950s. As the death penalty fell into disuse in the 1960s, the homicide rate rose sharply. The death penalty moratorium that began with Furman in 1972 and ended with Gregg in 1976 appears to have been a period in which the homicide
rate rose. The homicide rate then remained high and variable through the 1980s while the rate of executions rose. Finally, homicides dropped dramatically during the 1990s. By any measure the resumption of the death penalty in recent decades has been fairly minor, and both the leve l of the execution rate and its year-to-year changes are tiny: since
1960 the proportion of homicides resulting in execution ranged from 0% to 3%. By contrast, these was much greater variation in execution rates over the previous sixty years, when the execution rate ranged from 2.5% to 18%. This immediately hints that – even with modern econometric models – it is unlikely that the last few decades generated enough variation in execution rates to overturn earlier conclusions about the deterrent effect of capital punishment.'[68]
"Donohue and Wolfers also examine murder rates in the US and Canada across decades. This leads to the conclusion that 'the homicide rate in Canada has moved in virtual lockstep with the rate in the United States, while approaches to the death penalty have diverged sharply.'[69]
"Finally, Donohue and Wolfers compare murder rates in states that have the death penalty with states that do not have the death penalty. Based on a comparison of six states that did not execute anyone from 1960 to 2000 and all other states, they conclude:
'Both sets of states experienced higher homicide rates during the death penalty moratorium than over the subsequent decade; the gap widened for the subsequent decade and narrowed only in the late 1990s. It is very difficult to find evidence of deterrence ... most of the action in homicide rates in the United States is unrelated to capital punishment
... most of the variation in homicide rates in driven by factors that are common to both death penalty and non-death penalty states.'[70]
"This explains why states that did not change their capital punishment laws had similar changes in murder rates over time to those that abolished or reinstated capital punishment.
"After re-examining the data from the various pro-deterrence articles, Donohue and Wolfers explain
'we find considerable variation in the estimated relationship between execution and murder rates. Our reading of these results suggests (weakly) that the preponderance of the evidence supports the view that increases in executions are associated with increases in lives lost, although further permutations of the full array of plausible models would be needed before strong conclusions could be reached.'[71]
"That is, there is more evidence of a brutalization effect of executions than a deterrent effect. Whatever the case, the bottom line, according to Donohue and Wolfers, is that '[t]he view that the death penalty deters is still the product of
belief, not evidence. The reason for this is simple: over the past half century the U.S. has not experimented enough with capital punishment policy to permit strong conclusions ... On balance, the evidence suggests that the death penalty may increase the murder rate although it remains possible that the death penalty may decrease it. If capital punishment does decrease the murder rate, any decrease is likely small. In light of this evidence, is it wise to spend millions on a process
with no demonstrated value that creates at least some risk of executing innocents when other proven crime-fighting measures exist? Even consequentialists ought to balk.'[72]
"In response to this article, Paul Rubin, author of one of the pro-deterrence articles, claims that 'They simply found different models and data yielded different results. Moreover, in my Congressional testimony, I cited not only my own article but a total of 12 studies by 15 different authors that find a deterrent effect.'[73] In a reply to this reply, it is claimed that, in the original study claiming to find that capital punishment prevents 18 homicides, 'Rubin and coauthors
described their key instrument for executions as ‘the Republican presidential candidate’s percentage of the statewide vote in the most recent election.’ But, we found that using that precise instrument leads to the exact opposite finding that they reached: each execution causes 18 more homicides.'[74]
"Another capital punishment expert, Jeffrey Fagan, in testimony to the Massachusetts Joint Committee on the Judiciary (which was considering legislation to initiate a 'foolproof' death penalty), commented that: 'A close reading of the new deterrence studies shows quite clearly that they fail to touch this scientific bar, let alone cross it.' He was referring to standards of social science research.[75] Among his specific concerns were 'technical and conceptual errors, including
inappropriate methods of statistical analysis, failures to consider all relevant factors that drive murder rates, missing data on key variables in key states, weak to non-existent tests of concurrent effects of incarceration, and other deficiencies.'[76]
"Finally, an article by Sociologist Ted Goertzel about the main methodology used by economists in studies such as the recent pro-deterrence studies, leads to this conclusion:
'It would be handy for social scientists if we lived in a Flatland ... [where everything moves along straight lines, flat plains, or rectangular boxes ... and] ... where everything else was equal and questions could be answered with a few calculations. But multivariate statistical analysis does not answer real-world questions such as, 'does Texas, with a high execution rate, have a lower homicide rate than similar states?' or 'did the homicide rate go down when Texas began
executing people, compared to trends in other states that did not?' Instead, it answers the question, 'If we use the latest, most sophisticated statistical methods to control for extraneous variables, can we say that the death penalty deters homicide rates other things being equal?' After decades of effort by many diligent researchers, we now know the answer to this question: There are many ways to adjust things statistically, and the answer will depend on which one is chosen.
We also know that of the many possible ways to specify a regression model, each researcher is likely to prefer one that will give results consistent with his or her predispositions.'
...
' It is time to abandon the illusion that mathematics can convert the real world into the mythical land of Ceteris Paribus ... [a place where everything is constant except the variables they choose to write about.] ... Social science can provide valid and reliable results with methods that present the data with as little statistical manipulation as possible and interpret it in light of the best qualitative information available. The value of this research is shown by its success in
demonstrating that capital punishment has not deterred homicide.'[77]
"The research finding a deterrent effect of executions is also inconsistent with views of law enforcement chiefs[78] and the views of the many major organizations who have taken a stand against capital punishment, including the American Society of Criminology (ASC). ASC’s National Policy Committee (NPC) states:
'The NPC’s review of the scientific literature has observed little evidence that the death penalty has a deterrent effect on violent crimes. A comparison of homicide rates both pre- and post-death penalty eras have not shown a deterrent effect, either within a single state or between states. More troubling are studies showing that the application of the death penalty is not carried out in an equitable manner and is often based on non-legal factors such as the defendant’s or victim’s race and socio-economic status. Finally, a number of well-publicized cases within the U.S. have shown wrongful convictions for persons sentences to death due to improper prosecutorial and sentencing practices as well as inadequate defense counsel.'[79]
"Further, the survey of Presidents of American Society of Criminology (ASC), the Academy of Criminal Justice Sciences (ACJS), and the Law and Society Association (LSA), introduced in Chapter 3, found that:
* 84% say death penalty is not a deterrent to homicide;
* 93% say the threat of the death penalty is not a greater deterrent to murder than long prison terms;
* 87% say abolishing the death penalty in a state would have no significant effects of murder in that state;
* 0% say the death penalty significantly reduces homicide;
* 100% say politicians support death penalty to appear tough on crime; and
* 87% say debates about death penalty distract law makers from focusing on real solutions to crime problems.[80]
"While the surveys of law enforcement chiefs and the presidents of ASC, ACJS, and LSA, and the conclusion of the American Society of Criminology’s (ASC) National Policy Committee preceded the studies finding a deterrent effect of executions, it is doubtful given the problems with the pro-deterrence studies that the minds of these individuals would be changed.
"Stated plainly, the facts refute the findings of econometric studies claiming to find a deterrent effect of modern executions. Executions have become rarer and thus less certain, and the capital punishment process has become slower and thus less swift. If anything, one should not even expect to find a deterrent effect – any deterrent effect
present in periods when executions were more common and the process occurred more quickly should now be absent. The evidence simply flies in the face of deterrence.
"Summary of Deterrence.
The experts indicated their strong belief that capital punishment, as actually practiced by states in the United States, does not achieve the goal of deterrence. This is largely due to the rare nature of the punishment; the death penalty is too rarely used for it to be a certain enough punishment to cause fear in world-be murderers. The facts show that capital punishment is extremely rare and that it does not reduce murder through deterrence."
Now, on top of all this, the experts overwhelimingly agreed that the death penalty is racially biased and biased against people in the lower class, and is likely to be used against the innocent.
I hope you will consider all this when debating the death penalty in North Carolina. A state-wide study in North Carolina will find the same results as my study.
Sincerely,
Matthew Robinson, PhD
Footnotes
[28]. Bailey, W., and R. Peterson (1997). Murder, capital punishment, and deterrence: A review of the literature. In H. Bedau (Ed.), The Death Penalty in America: Current Controversies. New York: Oxford.
[29]. Bailey and Peterson (1997), p. 137.
[30]. Bohm, B. (2003). DeathQuestII: An Introduction to the Theory and practice of Capital Punishment in the United States. Cincinnati, OH: Anderson; Bailey and Peterson (1997), p. 138.
[31]. Hood, R. (2002). The Death Penalty: A Worldwide Perspective. New York: Oxford University Press, p. 217, summarizing Sellin, T. (1959). The Death Penalty (1959). Philadelphia, PA: American Law Institute; and Bowers, W., Pierce, G., and J. McDeavitt (1984). Legal Homicide: Death as Punishment in America, 1864-1982. Boston, MA: Northeastern University Press.
[32]. See Lempert, R. (1983). The effect of executions on homicides: A new look in an old light. Crime and Delinquency 29: 88-115; Peterson, R., and W. Bailey (1998). Is capital punishment an effective deterrent for murder? An examination of social science research. In Acker, J., Bohm, B., and C, Lanier (Eds.), America’s Experiment with Capital Punishment: Reflections on the Past, Present, and Future of the Ultimate Penal Sanction. Durham, NC: Carolina Academic Press.
[33]. According to two deterrence experts, this is consistent with a lack of deterrence, “but it does not does not prove that capital punishment is not a deterrent to murder. Nor does it prove that capital punishment produces higher homicide rates (brutalization). It is possible that death penalty and abolitionist jurisdictions in the U.S. differ in other significant respects which influence lethal violence.” Peterson, R., and W. Bailey (2003). Is capital punishment an effective deterrent for murder? An examination of social science research. In Acker, J., Bohm, B., and C, Lanier (Eds.), America’s Experiment with Capital Punishment: Reflections on the Past, Present, and Future of the Ultimate Penal Sanction (Second Edition). Durham, NC: Carolina Academic Press, p. 254.
[34]. The opposite happened in the United States – when executions slowed in the 1960s and stopped in the 1970s – homicides rose. See Carrington, F. (1978). Neither Cruel Nor Unusual. New Rochelle, NY: Arlington). However, the simple correlation between falling executions and rising homicide rates was spurious, since it did not control for
“the lower costs and greater availability of weapons, increased racial tension, a general reduction in the severity of prison sentences, ... an increased gap between people’s economic expectations and their actual economic status ... [and] the effect of the postwar baby boom, which resulted in a great increase in the size of the most violent group
within society, males between eighteen and twenty-five years old.” Further: “While the homicide rate did increase, it increased at a much slower rate than other crimes, which really did skyrocket during his period. Since the death penalty had never been a factor in these other crimes, its absence could not have accounted for their increase.’ Finally, in
comparative studies of homicide increases in abolitionist and retentionist counties, “there was no evidence that death penalty states experienced greater increases as a result of the moratorium and their inability to execute murderers.” Nathanson, S. (2001). An Eye for an Eye: The Immorality of Punishing by Death. Lanham, MD: Rowman & Littlefield, pp. 27-28.
[35]. Bohm (2003); Peterson and Bailey (2003).
[36]. For specific studies and their findings, see Peterson and Bailey (2003), pp. 261-273.
[37]. Ehrlich, I. (1975). The deterrent effect of capital punishment: A question of life and death. American Economic Review 65: 397-417.
[38]. Beyleveld, D. (1982). Ehrlich’s analysis of deterrence. British Journal of Criminology 22: 101-123; Forst, B. (1977). The deterrent effects of capital punishment: A cross-state analysis. Minnesota Law Review 61: 743-767. For a discussion of other replications, see Bailey and Peterson (1997).
[39]. Cassell, P. and Taylor, J. (1977). The deterrent effect of capital punishment: Another view. American Economic Review 67: 445.
[40]. Bailey and Peterson (1997), p. 142.
[41]. National Academy of Sciences (1978). Deterrence and Incapacitation: Estimating the Effects of Criminal Sanctions on Crime Rates (Blumstein, A., et al).
[42]. Bailey, W. (1998). Deterrence, brutalization, and the death penalty: Another examination of Oklahoma's return to capital punishment. Criminology 36(4): 711; Cochran, J., and M. Chamlin (2000). Deterrence and brutalization: The dual effects of executions. Justice Quarterly 17(4): 685; Cochran, J., Chamlin, M., and M. Seth (1994). Deterrence or brutalization? An impact assessment of Oklahoma's return to capital punishment. Criminology 32(1): 107; Peterson, R. and W. Bailey (1991). Felony Murder and Capital Punishment: An Examination of the Deterrence Question. Criminology 29(3): 367; Sorensen, J., Wrinkle, R., Brewer, V., and J. Marquart (1999). Capital punishment and deterrence: Examining the effect of executions on murder in Texas. Crime and Delinquency 45(4): 481-493. Stack, S. (1993). Execution
publicity and homicide in Georgia. American Journal Of Criminal Justice 18(1): 25-39;
Thomson, E. (1997). Deterrence versus brutalization: The case of Arizona. Homicide Studies 1(2): 110-128; Yunker, J. (2001). A new statistical analysis of capital punishment incorporating U.S. postmoratorium data. Social Science Quarterly 82(2): 297-311.
[43]. Bailey and Peterson (1997), p. 155.
[44]. Pojman and Reiman (1998).
[45]. Van den Haag, E. (1997). The death penalty once more. In Bedau, H. (Ed.), The Death Penalty in America: Current Controversies. New York: Oxford University Press, p. 449.
[46]. Pojman and Reiman (1998); Pojman, L. (2004).
[47]. van den Haag, E. (1968). On deterrence and the death penalty. Ethics 78.
[48]. Pojman and Reiman (1998).
[49]. Cassell, P. (2004); Pojman, L. (2004); Pojman and Reiman (1998).
[50]. Brumm, H., and D. Cloninger (1996). Perceived risk of punishment and the commission of homicides: A covariance structure analysis. Journal of Economic Behavior and Organization 31(1): 1-11; Cloninger, D., and R. Marchesini (2001). Execution and deterrence: A quasicontrolled group experiment. Applied Economics 33(5): 569-576; Cloninger, D., and R. Marchesini (2005). Execution moratoriums, commutations and deterrence: The case of Illinois. [Online].
Available: http://www.cjlf.org/deathpenalty/IllStudyRevised.pdf; Dezhbakhsh, H., Rubin, P., and J. Shepherd (2003). Does capital punishment have a deterrent effect? New evidence from postmoratorium panel data. American Law & Economics Review 5(2): 344-376; Dezhbakhsh, H., and J. Shepherd (2003). The deterrent effect of capital punishment:
Evidence from a “judicial experiment.” Department of Economics, Emory University. Working Paper No. 03-14. [Online]. Available: http://people.clemson.edu/~jshephe/CaPuJLE_submit.pdf; Ehrlich, I., and Z. Liu (1999). Sensitivity analysis of the deterrence hypothesis: Lets keep the econ in econometrics. Journal of Law and Economics 42(1): 455-487; Mocan, H., and R. Gittings (2003). Getting off death row: Commuted sentences and the deterrent effect of capital punishment. Journal of Law and Economics 46(2): 453-478; Shepherd, J. (2004). Murders of passion, execution delays, and the
deterrence of capital punishment. Journal of Legal Studies 33 (2): 283-322; Zimmerman, P. (2004). State executions, deterrence and the incidence of murder. Journal of Applied Economics 7(1): 163-193.
[51]. Shepherd (2004).
[52]. Mocan, H., and R. Gittings (2003). Getting off death row: Commuted sentences and the deterrent effect of capital punishment. Journal of Law and Economics 46(2): 453-478.
[53]. Zimmerman (2004).
[54]. Dezhbakhsh et al. (2003).
[55]. Dezhbakhsh and Shepherd (2005).
[56]. Terrorist Penalties Enhancement Act of 2003: Hearing on H.R. 2934 Before the Subcommittee on Crime, Terrorism, and Homeland Security of the House Committee on the Judiciary, 2004, 108th Congress, 10-11. [Online]. Available:
http://judiciary.house.gov/media/pdfs/printers/108th/93224.pdf.
[57]. For a good discussion of methodological issues related to deterrence research generally, see Hood, R. (2002).
[58]. Berk, R. (2004). New claims about execution and general deterrence: Deja vu all over again?
Journal of Empirical Legal Studies. [online]. Available: http://preprints.stat.ucla.edu/396/JELS.pap.pdf.
[59]. Donohue, J., and J. Wolfers (2005). Uses and abuses of empirical evidence in the death penalty debate. Stanford Law Review 58: 791-846, pp. 814-815.
[60]. Shepherd (2005).
[61]. Some of the invalid instruments include “1) the statewide aggregate number of prison admissions; 2) total statewide aggregate police payrolls; 3) judicial expenditures (albeit not adjusted for inflation or state size); and 4) the statewide percent Republican vote in the most recent Presidential election” (Donohue, J., and J. Wolfers (2006). The death penalty: No evidence for deterrence. The Economists’ Voice April: 3. The authors explain: “To be valid, they would have to
influence executions and there would have to be no other link between these variables and the homicide rate. This is not the case.”
[62]. An example of a valid confidence interval from one of the studies ranges “from 429 lives saved per execution to 86 lives lost” which is “outside the bounds of credibility” (Donohue and Wolfers, 2006, p. 3).
[63]. Donohue and Wolfers (2005), pp. 825-826.
[64]. Donohue and Wolfers (2005), p. 827.
[65]. Donohue and Wolfers (2005), p. 794.
[66]. Donohue and Wolfers (2005), p. 836.
[67]. Donohue and Wolfers (2005), pp. 841, 843.
[68]. Donohue and Wolfers (2005), pp. 796-797.
[69]. Donohue and Wolfers (2005), p. 799.
[70]. Donohue and Wolfers (2005), p. 801.
[71]. Donohue and Wolfers (2006), p. 5.
[72]. Donohue and Wolfers (2006), pp. 5-6.
[73]. Rubin, P. (2006). The death penalty once more. The Economists’ Voice April: 1.
[74]. Donohue, J., and J. Wolfers (2006). A reply to Rubin on the death penalty. The Economists’ Voice April: 1.
[75]. Fagan, J., Public Policy Choices on Deterrence and the Death Penalty: A Critical Review of New Evidence, testimony before the Joint Committee on the Judiciary of the Massachusetts Legislature on House
Bill 3934, July 14, 2005, Online: (http://www.deathpenaltyinfo.org/MassTestimonyFagan.pdf).
[76]. Death Penalty Information Center (2006). Deterrence news and developments – Previous years. [Online]. Available:
http://www.deathpenaltyinfo.org/article.php?did=1705).
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