Volume 22, No. 1,
The Scientific Evidence
Statement Before the Joint Interim Health and Welfare Committee
Gary W. Potter, PhD.
There is probably no public policy issue related to crime control that
has been researched and studied over as long a period of time as the death
penalty; in more varied ways than the death penalty; or in greater volume
than the death penalty. Put simply, the dilemma is this: there is no crime
control issue we know more about than the death penalty and there is no
crime control issue where the scientific research has been more ignored
by decision-makers and the public than the death penalty. The fact is that
the death penalty debate is much more than a matter of conflicting opinions,
morals, ethics, and values. There are a plethora of well established, scientifically
documented facts at the disposal of both the public and lawmakers. These
facts have emanated from research that has been replicated over and over
again and subjected to the most rigorous scientific review process available.
These facts are well beyond refutation. In sum, it is fair to say to a
level of certainty that far exceeds the most rigorous standards of proof
in any court in America, that the death penalty, as presently constructed
and administered is deplorably bad public policy. In studies using entirely
different methodologies, at different times, in different places, constructing
research questions in different ways, the facts are immutable and unchanging.
The scientifically proven facts of the death penalty are clear. Those facts
The overwhelming body of scientific studies supporting each of these propositions is presented in a written addendum to my testimony, summarizing every important scholarly study on the death penalty since 1980. I believe that if you take the time to read that scientific evidence it will become obvious that the weight of the scientific evidence against the death penalty is not just in preponderance, it is overwhelming and virtually unrefutable.
I have been asked today to specifically discuss in some detail issues of cost, deterrence and brutalization. Allow me to begin with the evidence on cost.
The Cost of the Death Penalty
One of the least obvious, but most important problems with the death penalty is it’s enormous cost. Research on cost has consistently shown that pursuing a capital case is at least twice as costly as housing a convicted murderer for life in a high security correctional institution. Cost studies in North Carolina, Kansas, Texas, Kentucky, Nebraska and New York all show varying costs but similar ratios with regard to expense of death as a sentencing option:
The death penalty also has a negative impact on the ability of criminal justice agencies to carry out their missions and perform their duties. The immense cost of the death penalty endangers the public in tangible and compelling ways as these examples indicate:
There are a large number of factors which come together to create the exceptionally high costs associated with the death penalty. First of all, both procedural and substantive constitutional safeguards put in place by the Supreme Court in death penalty cases drive up trial costs and the cost of appeals. As a result there is limited plea bargaining in death penalty cases (a factor which keeps down costs in all other prosecutions); there are lengthy pretrial motions; extensive investigations; increased use of expert witnesses; extensive voir dire; preemptory challenges; and extensive trial and appeal processes. Virtually none of these requirements are subject to reform or state recourse because they were necessitated by Supreme Court guidelines for the death penalty. In addition, almost every capital defendant in America is poor and taxpayers must invariably pay defense costs.
Let me emphasize two issues here:
In view of the fact, as we shall in the next portion of my testimony, that scientific research can establish no incapacitative or deterrent benefit from the death penalty, this cost is entirely wasted.
The most commonly advanced argument in support of capital punishment has been that no offender wants to die, therefore the threat of execution will deter homicide in society at large. While this may seem a common sense fact, it is anything but sensible. The scientific facts are very simple. No credible study of capital punishment in the United States has ever found a deterrent effect.
In studies of contiguous states, at least one with the death penalty and at least one without, research has shown that there is no deterrent impact from capital punishment (Sellin, T. 1980. The Penalty of Death. Beverly Hills, CA: Sage Publications).
In studies of states where the death penalty was adopted or reinstated after having been abolished, research has once again failed to show any deterrent effect. (Sellin, T. 1980. The Penalty of Death. Beverly Hills, CA: Sage Publications; Zeisel, H. 1977. The deterrent effect of the death penalty: Facts v. Faith. In The Supreme Court Review 1976. P. Kurland (ed.). Chicago: IL: University of Chicago Press).
Comparative data also fails to demonstrate any deterrent value to the death penalty. The United States is the only Western democracy that retains the death penalty. The United States also has, far and away, the highest homicide rate in the industrialized world (Kappeler, V., M. Blumberg, and G. Potter. 1996. The Mythology of Crime and Criminal Justice (2nd ed.). Prospect Heights, IL: Waveland Press: 310).
Comparative data compiled by region within the United States shows the same pattern. According to data from the Bureau of Justice Statistics, Southern states have consistently had the highest homicide rates in the country. In 1997, the South was the only region with a homicide rate above the national average, despite the fact that it accounts for 80% of all executions. The Northeast, which accounts for less than 1% of all executions in the U.S., has the lowest homicide rate. Similarly, when states with the death penalty are compared to those without the death penalty, the data show that a majority of death penalty states have homicide rates higher than non-death penalty states. In 1997 the average homicide rate for death penalty states was 6.6, while the average homicide rate for non-death penalty states was only 3.5.
The alleged deterrent value of the death penalty is refuted by all the
data we have on violent crime. The death penalty, if it is to deter, must
be a conscious part of a cost-benefit equation in the perpetrator’s mind.
There are very few murders that involve that level of rationality or consciousness
of the outcomes. Most murders are (1) committed under the influence of
drugs or alcohol; (2) committed by people with severe personality disorders;
(3) committed during periods of extreme rage and anger; or (4) committed
as a result of intense fear. None of these states of mind lend itself to
the calm reflection required for a deterrent effect.
Some proponents of the death penalty argue that capital punishment provides a specific deterrent which controls individuals who have already been identified as dangerous criminal actors. According to this argument, the presence of the death penalty ought to reduce a wide variety of criminal acts. The weight of scientific evidence tells us that it does not.
If the death penalty deters homicide then it should prevent incarcerated people from killing again and reduce the number of homicides among prisoners. The fact of the matter is that over 90% of all prisoner homicides, killings of other prisoners or correctional officers, occur in states with capital punishment (Sellin, T. 1980. The Penalty of Death. Beverly Hills, CA: Sage Publications).
An extensive death penalty study, using multiple means of measurement that measured the impact of capital punishment in three distinct and different ways could find no evidence that the death penalty had any effect on felony crime rates, "this pattern holds for the traditional targeted offense of murder, the personal crimes of negligent manslaughter, rape, assault and robbery, as well as the property crimes of burglary, grand larceny, and vehicle theft. In other words, there is no evidence ... that residents of death penalty jurisdictions are afforded an added measure of protection against serious crimes by executions" (Bailey, W. 1991. The general prevention effect of capital punishment for non-capital felonies. In R. Bohm (ed.) The Death Penalty in America: Current Research. Cincinnati, OH: Anderson and the Academy of Criminal Justice Sciences).
Finally, it has been argued that capital punishment specifically protects law enforcement officers by deterring assaults on and killings of police. There have been five major studies addressing the question of whether capital punishment protects police officers. In no case did the death penalty provide any deterrent to killing law enforcement officers, nor did it reduce the rate of assaults on police (Bailey, W. and R. Peterson. 1987. Police killings and capital punishment: The post-Furman period. Criminology 25, 1: 1-25; Bailey, W. 1992. Capital punishment and lethal assaults against police. Criminology 19: 608-625; Sellin, T. 1980. The Penalty of Death. Beverly Hills, CA: Sage Publications; Cardarelli, A. 1968. An analysis of police killed in criminal action: 1961-1963. Journal of Criminal Law, Criminology, and Police Science. 59: 447-453; Hunter, R. and R. Wood. 1994. Impact of felony sanctions: An analysis of weaponless assaults upon police. American Journal of Police 13, 1: 65-89).
Once again the scientific evidence is clear, the death penalty does not provide specific deterrence from other crimes. It has no deterrent impact on other felonies, it has no deterrent impact on crimes against law enforcement officers, it has no deterrent impact on drug crimes, and it has no deterrent impact on violent crimes. In fact, the death penalty is more likely to endanger the lives of police who investigate crime and pursue fugitives, and endanger the lives of witnesses who may provide evidence necessary for conviction. The reason is obvious, preventing capture and conviction becomes far more pressing a matter in death penalty states.
Another frequently advanced argument is that the death penalty protects society by incapacitating violent criminals and thereby preventing further offenses. The evidence for this proposition is also weak. Obviously, an executed murderer is unlikely to recidivate, but so is a murderer in prison for life without parole. The facts, however, indicate that even if not executed and even if not incarcerated for life, it is unlikely that a person convicted of homicide will kill again, or even commit an additional serious offense.
A massive study which tracked the post-release behavior of 6,835 male prisoners serving sentences for homicide offenses, who were paroled from state institutions, found that only 4.5% of them were subsequently convicted of another violent crime and only 0.31% committed another homicide (Sellin, T. 1980. The Penalty of Death. Beverly Hills, CA: Sage Publications). This means that for every 323 executions we might prevent one additional murder. Other studies find essentially the same results. For example, a study of prisoners whose sentences were commuted as a result of the Furman decision (Marquart, J. and J. Sorensen. 1988. Institutional and post-release behavior of Furman-commuted inmates in Texas. Criminology 26: 677-693), found that 75 percent of these inmates committed no serious infractions of prison rules, and none of these inmates were involved in a prison homicide. Some of the Furman-commuted inmates were paroled back into the community. Only 14 percent of them committed a new crime, and only one committed an additional homicide.
Vito, Koester and Wilson (1991) also analyzed the behavior of inmates removed from death row as a result of the Furman decision. Their study found that of those inmates eventually paroled only 4.5% committed another violent crime and only 1.6 percent committed another homicide. The authors conclude "that societal protection from convicted capital murderers is not greatly enhanced by the death penalty" (Vito, G., P. Koester, and D. Wilson. 1991. Return of the dead: An update on the state of Furman-commuted death row inmates. In R. Bohm (ed.) The Death Penalty in America: Current Research. Cincinnati, OH: Anderson and the Academy of Criminal Justice Sciences).
Even in states with capital punishment the overwhelming majority of people convicted of homicide receive a prison sentence, and many of them will eventually be released on parole. A review of the data on these released murderers clearly reveal that they have the lowest recidivism rates of any felons. In addition, paroled murderers in states without the death penalty had a much lower rate of recidivism than parolees released in states with the death penalty (Bedau, H. (ed.) 1982. The Death Penalty in America. 3rd ed. Oxford: Oxford University Press).
The death penalty does not protect society from further crimes of violence in any way. Eleven additional studies from the National Criminal Justice Reference Service database for the period 1980-1998 all fail to find any general or specific deterrent or any incapacitive impact from the use of the death penalty (Bailey, W.C. and R.D. Peterson. 1994.Murder, Capital Punishment, and Deterrence: A Review of the Evidenceand an Examination of Police Killings. Journal of Social Issues 50, 2: 53-74; Cheatwood, D. 1993. Capital Punishmentand the Deterrence of Violent Crime in Comparable Counties. Criminal Justice Review 18, 2: 165-181; Grogger, J. 1990. Deterrent Effect of Capital Punishment: An Analysis of Daily Homicide Counts. Journal of the American Statistical Association 85, 410: 295-303; Decker, S. H. and C. W. Kohfeld. 1990. Deterrent Effect of Capital Punishment in the Five Most Active Execution States: A Time Series Analysis. Criminal Justice Review 15, 2: 173-191; Decker, S.H. and C.W. Kohfeld. 1987. Empirical Analysis of the Effect of the Death Penalty in Missouri. Journal of Crime and Justice 10, 1: 23-46; Decker, S.H. and C. W. Kohfeld. 1986.Deterrent Effect of Capital Punishment in Florida: A Time Series Analysis. Criminal Justice Policy Review 1, 4: 422-437; Decker, S.H. and S.W. Kohfeld. 1984. Deterrence Study of the Death Penalty in Illinois, 1933-1980. Journal of Criminal Justice 12, 4: 367-377; Archer, D., R. Gartner and M. Beittel. 1983. Homicide and the Death Penalty - A Cross-National Test of a Deterrence Hypothesis. Journal of Criminal Law and Criminology 74, 3: 991-1013; Forst, B. 1983. Capital Punishment and Deterrence - Conflicting Evidence?Journal of Criminal Law and Criminology 74, 3: 927-942).
The Brutalization Effect of the Death Penalty
Neither incapacitation nor deterrence theories are supported by the scientific research on capital punishment. In most public policy debates the burden of proof is on those advocating a measure to demonstrate its effectiveness. If that were the case in the death penalty debate adherents would fail miserably. But the fact is that the death penalty not only doesn’t deter murder, it encourages people to kill.
Studies of capital punishment have consistently shown that homicide actually increases in the time period surrounding an execution. Social scientists refer to this as the "brutalization effect." Execution stimulates homicides in three ways: (1) executions desensitize the public to the immorality of killing, increasing the probability that some people will be motivated to kill; (2) the state legitimizes the notion that vengeance for past misdeeds is acceptable; and (3) executions also have an imitation effect, where people actually follow the example set by the state, after all, people feel if the government can kill its enemies, so can they (Bowers and Pierce, 1980; King, 1978, Forst. 1983).
Let me clear here. The scientific evidence on the brutalization effect
is compelling. We are not talking about one or two speculative studies.
We are talking about a body of research that has found over and over again,
in state after state, that the use of the death penalty increases, and
often sharply increases, the number of homicides. Let me be specific:
Criminologists and criminal justice scholars are constrained to make their judgments on facts and scientifically valid and reliable scholarly research. It is the judgment of the overwhelming majority of criminologists and criminal justice scholars that the death penalty is bad policy and is in fact criminogenic in its social impact. The American Society of Criminology, an organization made up of the best researchers and scholars in the country, has strongly condemned the death penalty:
Be it resolved that because social science research has demonstrated the death penalty to be racist in application and social science research has found no consistent evidence of crime deterrence through execution, the ASC publicly condemns this form of punishment and urges its members to use their professional skills in legislatures and the courts to seek a speedy abolition of this form of punishment (ASC Annual Meeting, Montreal, 1987).
The scientific evidence on the death penalty is clear and unequivocal.
The use of the death penalty in American society is the rough equivalent
of a person hitting himself or herself repeatedly on the head with a hammer
in order to treat a headache resulting from a brain tumor. It can only
make a very bad situation much worse. This judgment is not based upon vague
conceptions of morality or popular formulations of common sense or the
vagaries of political opinion, it is based on rigorous evaluation of the
state's two primary responsibilities: (1) to protect the public health
and safety; and (2) to provide equity, fairness and justice to its citizens.
The death penalty is anathema to both goals. It is the worst kind of crime-control