Robert Weisberg, JD, PhD, Edwin E. Huddleson, Jr. Professor of Law at Stanford University Law School, in his Dec. 2005 Annual Review of Law and Social Science article titled "The Death Penalty Meets Social Science: Deterrence and Jury Behavior Under New Scrutiny," wrote:
"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(2,943KB), 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."
Donald L. Beschle, LLM, Professor of Law at the John Marshall Law School in Chicago, in a Jan. 1997 William and Mary Law Review essay titled "What's Guilt (or Deterrence) Got to Do With It? The Death Penalty, Ritual, and Mimetic Violence," wrote:
"...deterrence theory seems less and less central to the debate, even as it is understood currently. Most abolitionists and retentionists seem committed to their positions regardless of the evidence on deterrence. Deterrence seems to be an argument added to bolster a position already taken."
David B. Muhlhausen, PhD, Senior Policy Analyst at the Heritage Foundation's Center for Data Analysis, in testimony delivered on June 27, 2007 before the Subcommittee on the Constitution, Civil Rights, and Property Rights of the US Senate Judiciary Committee, stated:
"The recent studies using panel data techniques have confirmed what we learned decades ago: Capital punishment does, in fact, save lives [...]Over the years, several studies have demonstrated a link between executions and decreases in murder rates. In fact, studies done in recent years, using sophisticated panel data methods, consistently demonstrate a strong link between executions and reduced murder incidents. Using a panel data set of over 3,000 counties from 1977 to 1996, Professors Hashem Dezhbakhsh [and] Shepherd of Emory University found that each execution, on average, results in 18 fewer murders (268KB) [...]
They found that executions had a highly significant negative relationship with murder incidents. Additionally, the implementation of state moratoria is associated with the increased incidence of murders... While opponents of capital punishment allege that it is unfairly used against African–Americans, each additional execution deters the murder of 1.5 African–Americans. Further moratoria, commuted sentences, and death row removals appear to increase the incidence of murder... Americans support capital punishment for two good reasons. First, there is little evidence to suggest that minorities are treated unfairly. Second, capital punishment produces a strong deterrent effect that saves lives."
Robert B. Ekelund, PhD, Professor of Economics and Lowder Eminent Scholar Emeritus at Auburn University, et. al, in a Jan. 2006 Southern Economic Journal article titled "Marginal Deterrence and Multiple Murders," wrote:
"However strongly, execution variables deter first and only murders, the marginal cost of additional murders is, in effect, zero. Empirically, we find that execution and the death penalty have no significant effect on multiple murders... our study also shows that... single murders are deterred by execution variables... the form of execution --electrocution being considered marginally more 'painful' than lethal injection-- is an added deterrent to single murders..."
George W. Bush, MBA, 43rd President of the United States, in an Oct. 17, 2000 Third Bush-Gore debate at Washington University, answering to the question "Do both of you believe that the death penalty actually deters crime?," stated:
"I do, that’s the only reason to be for it. I don’t think you should support the death penalty to seek revenge. I don’t think that’s right. I think the reason to support the death penalty is because it saves other people’s lives."
George E. Pataki, JD, 53rd. Governor of New York State, in an Aug. 30, 1996 press release titled "Statement on Anniversary of Death Penalty by Governor Pataki," stated:
"New Yorkers live in safer communities today because we are finally creating a climate that protects our citizens and causes criminals to fear arrest, prosecution and punishment. ...this has occurred in part because of the strong signal that the death penalty sent to violent criminals and murderers: we won't excuse criminals, we will punish them... I sponsored the death penalty laws because of my firm conviction that it would act as a significant deterrent and provide a true measure of justice to murder victims and their loved ones... I have every confidence that it will continue to deter murders, will continue to enhance public safety and will be enforced fairly and justly."
Ernest Van Den Haag, PhD, late Professor of Jurisprudence at Fordham University, in an Oct. 17, 1983 New York Times "Op-Ed" article titled "For the Death Penalty," wrote the following:
"Common sense, lately bolstered by statistics, tells us that the death penalty will deter murder, if anything can. People fear nothing more than death. Therefore, nothing will deter a criminal more than the fear of death. Death is final. But where there is life there is hope... Wherefore, life in prison is less feared. Murderers clearly prefer it to execution -- otherwise, they would not try to be sentenced to life in prison instead of death. (Only an infinitesimal percentage of murderers are suicidal.) Therefore, a life sentence must be less deterrent than a death sentence. And we must execute murderers as long as it is merely possible that their execution protects citizens from future murder."
Isaac Ehrlich, PhD, Professor of Economics at the State University of New York and prominent analyst of the "deterrence theory," in a June 1977 American Economic Review study titled "The Deterrent Effect of Capital Punishment: A Question of Life and Death," concluded:
"...the results of [this] empirical investigation are not inconsistent with the hypothesis that, on balance, capital punishment reduces the murder rate...
In view of the new evidence presented here, one cannot reject the hypothesis that law enforcement activities in general and executions in particular do exert a deterrent effect on acts of murder. Strong inferences to the contrary drawn from earlier investigations appear to have been premature.
In contrast, since the results of this investigation support the notion that execution exerts a pure deterrent effect on offenders, they can be used to suggest that other punishments, even those which do not have any preventive effect, can in principle serve as substitutes."
Lewis Franklin Powell, Jr., LLM, late Justice of the US Supreme Court, in a June 29, 1972 Furman v. Georgia dissenting opinion, stated:
"On the basis of the literature and studies currently available, I find myself in agreement with the conclusions drawn by the Royal Commission [Report on Capital Punishment, 1949-1953] following its exhaustive study of this issue:
'The general conclusion which we reach, after careful review of all the evidence we have been able to obtain as to the deterrent effect of capital punishment, may be stated as follows. Prima facie, the penalty of death is likely to have a stronger effect as a deterrent to normal human beings than any other form of punishment, and there is some evidence (though no convincing statistical evidence) that this is in fact so.'"
The American Civil Liberties Union (ACLU), in its Apr. 9, 2007 website presentation titled "The Death Penalty: Questions and Answers," offered the following:
"[T]here is no credible evidence that the death penalty deters crime more effectively than long terms of imprisonment. States that have death penalty laws do not have lower crime rates or murder rates than states without such laws. And states that have abolished capital punishment show no significant changes in either crime or murder rates.
The death penalty has no deterrent effect. Claims that each execution deters a certain number of murders have been thoroughly discredited by social science research. People commit murders largely in the heat of passion, under the influence of alcohol or drugs, or because they are mentally ill, giving little or no thought to the possible consequences of their acts. The few murderers who plan their crimes beforehand -- for example, professional executioners -- intend and expect to avoid punishment altogether by not getting caught. Some self-destructive individuals may even hope they will be caught and executed."
Richard Berk, PhD, Professor of Criminology and Statistics at the University of Pennsylvania, in his July 2005 Journal of Empirical Legal Studies study titled "New Claims about Execution and General Deterrence: Deja Vu All over Again?," concluded:
"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."
Janet Reno, LLB, former US Attorney General, in a Jan. 20, 2000 US Justice Department press release titled "Weekly Media Availability with Attorney General Janet Reno," stated:
“I have inquired for most of my adult life about studies that might show that the death penalty is a deterrent. And I have not seen any research that would substantiate that point.”
Marian J. Borg, PhD, Associate Professor of Sociology at the University of Florida, and Michael L. Radelet, PhD, Professor and Chair of the Department of Sociology at the same university when quoted, in an Aug. 2000 Annual Review of Sociology essay titled "The Changing Nature of Death Penalty Debates," wrote:
"In the early 1970s, the top argument in favor of the death penalty was general deterrence. This argument or hypothesis suggests that we must punish offenders to discourage others from committing similar offenses; we punish past offenders to send a message to potential offenders...
However, over the last two decades more and more scholars and citizens have realized that the deterrent effect of a punishment is not a consistent direct effect of its severity --after a while, increases in the severity of a punishment no longer add to its deterrent benefits. In fact, increases in a punishment's severity have decreasing incremental deterrent effects, so that eventually any increase in severity will no longer matter...
In short, a remarkable change in the way the death penalty is justified is occurring. What was once the public's most widely cited justification for the death penalty is today rapidly losing its appeal."
James S. Liebman, PhD, Simon H. Rifkind Professor of Law at Columbia Law School, in a Dec. 2000 Columbia Law Review essay titled "The Overproduction of Death," concluded:
"...there is no evidence that the American system of capital punishment is even modestly focused on deterrence. Most people who support the death penalty do so despite doubts that it deters. These doubts are well-founded. More important, unlike eighteenth-century England's mandatory death penalty, which was carried out in properly deterrent - meaning brutal and terrorizing - fashion, in the town square on market day, preceded by fiery sermonizing on the object lesson intended thereby, the late twentieth-century American death penalty seems designed to minimize deterrence."
William C. Bailey, PhD, Professor of Sociology at Cleveland State University, in a June 1980 Social Forces study titled "Deterrence and the Celerity of the Death Penalty: A Neglected Question in Deterrence Research," wrote:
"No support whatsoever is found for the argument that the certainty, or celerity [speed], of the death penalty provides an effective deterrent to murder.
Although some possible limitations of this investigation have been identified, the consistency of the findings with earlier studies cannot be ignored. Nor can it be ignored that not a single reputable study has yet to demonstrate the death penalty to be a more effective deterrent to murder than alternative legal sanctions...
For these reasons, and because of the seriousness of the issue, I feel obliged to agree with most previous investigators. The evidence clearly suggests that the death penalty in our criminal justice system, at least for murder, will have to be justified on grounds other than its deterrence effectiveness."
Thurgood Marshall, LLB, late Justice of the US Supreme Court, in a June 29, 1972 Furman v. Georgia concurrent opinion, stated:
"It is generally agreed between the retentionists and abolitionists, whatever their opinions about the validity of comparative studies of deterrence, that the data which now exist show no correlation between the existence of capital punishment and lower rates of capital crime.
Despite the fact that abolitionists have not proved non-deterrence beyond a reasonable doubt, they have succeeded in showing by clear and convincing evidence that capital punishment is not necessary as a deterrent to crime in our society.
In light of the massive amount of evidence before us, I see no alternative but to conclude that capital punishment cannot be justified on the basis of its deterrent effect."
(2,943KB), 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.
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