Deterrence and the death penalty: the views of the experts.

• Author: Radelet, Michael L.

1. INTRODUCTION

   The American public has long been favorably disposed toward capital punishment for convicted murderers, and that support continues to grow. In a 1981 Gallup Poll, two-thirds of Americans voiced general approval for the death penalty. That support rose to 72% in 1985, to 76% in 1991, and to 80% in 1994.(1) Although these polls need to be interpreted with extreme caution, it is clear that there are few issues on which more Americans agree: in at least some circumstances, death is seen as a justifiable punishment.

   Part of the support for capital punishment comes from the belief that the death penalty is legitimate under a theory of "just deserts."(2) This justification suggests that murderers should be executed for retributive reasons: murderers should suffer, and the retributive effects of life imprisonment are insufficient for taking a life. While such views are worthy of debate, no empirical research can tell us if the argument is "correct" or "incorrect." Empirical studies can neither answer the question of what specific criminals (or non-criminals) "deserve," nor settle debates over other moral issues surrounding capital punishment.

   On the other hand, much of the support for capital punishment rests on its presumed value as a general deterrent: we need the death penalty to encourage potential murderers to avoid engaging in criminal homicide.(3) Politicians are often quick to use some version of the deterrence rationale in their cries for more and quicker executions when they see such appeals as a promising way to attract votes.(4)

   Whether or not the threat or use of the death penalty is, has been, or could be a deterrent to homicide is an empirical question that should not--and cannot--be answered on the basis of moral or political stands. It is an empirical question that scores of researchers, dating back to a young Edwin Sutherland, writing in the pages of this journal,(5) have examined.

   Has this long history and sizeable body of research led to any general conclusions? Can any factual statement be made about the death penalty's deterrent effects, or are the scholarly studies such that no conclusions can be reached? At least two valid methods can be used to answer these questions. One is to examine individual scholarly opinions, as is done in most published research reports. Here researchers review the empirical research on deterrence and reach conclusions based on it and their own research. A second approach is to gauge the informed opinions of scholars or experts. Indeed, much research-based public policy rests on known or presumed consensus of "expert" opinions. It is the aim of this paper to address the question of the death penalty's ability to deter homicides using this second approach: by gauging the judgments of a set of America's top criminologists.

2. LITERATURE REVIEW

   Measuring sentiment on the death penalty is not as easy a task as it might at first appear. When opinion polls ask respondents whether they support the death penalty, often no alternative punishments are given, and respondents are left to themselves to ponder what might happen if a particular inmate were not executed. Often respondents erroneously believe that absent execution, offenders will be released to the community after serving a short prison sentence.(6) Even the most ardent death penalty abolitionists might support capital punishment if the alternative was to have dangerous murderers quickly released from prison. When respondents are asked how they feel about the death penalty given an alternative of life without parole, support decreases significantly.(7) In 1991, Gallup found that 76% of Americans supported the death penalty, but that support would drop to 53% if life imprisonment without parole were available as an alternative.(8)

   While most deterrence research has found that the death penalty has virtually the same effect as long-term imprisonment on homicide rates,(9) in the mid-1970's economist Isaac Ehrlich reported that he had uncovered a significant deterrent effect.(10) He estimated that each execution between 1933 and 1969 had prevented eight homicides.(11) This research gained widespread attention, in part because Solicitor General Robert Bork used it to defend the death penalty in the 1970s when the Supreme Court was considering whether to make permanent its 1972 ban of the death penalty.(12) Although scholars, including a panel appointed by the National Academy of Sciences,(13) strongly criticized Ehrlich's work for methodological and conceptual shortcomings,(14) some continue to cite it as proof that the death penalty does have a deterrent effect.(15) A student of Ehrlich's, Stephen Layson, later reported his estimate that each execution deterred approximately 18 homicides.(16) This research, too, was loudly criticized,(17) but nonetheless it continues to be embraced by proponents of the death penalty.(18)

   It could very well be that the mere existence of a critique is more important than the quality of that critique. One researcher finds one thing, and another claims to refute it. What is left is a net gain of zero: politicians who never read or understand the original studies can select either position and cite only those studies that support their position.

   Some research has asked the general public whether the death penalty acts as a deterrent to murder. Such a question is regularly asked to national samples in Gallup Polls.(19) In the mid-1980's, just over 60% of the respondents in Gallup polls said they believed the death penalty was a deterrent. Furthermore, these polls showed that the deterrence rationale is an important death penalty justification. In the 1986 Gallup Poll, respondents were asked if they would support the death penalty "if new evidence proved that the death penalty does not act as a deterrent to murder." Given this assumption of no deterrent effect, support for capital punishment dropped from 70% to 51%.(20)

   Similarly, in the 1991 poll, where 76% of the respondents initially indicated support for the death penalty, Gallup asked those who favored the death penalty: "Suppose new evidence showed that the death penalty does not act as a deterrent to murder, that it does not lower the murder rate. Would you favor or oppose the death penalty?" As in the earlier poll, the respondents were less likely (76% vs. 52%) to support capital punishment if it were shown that it is not a deterrent to homicide.(21) These findings indicate that the assumption of a deterrent effect is a major factor in public and political endorsement of the death penalty. If that assumption is undermined, even those who initially favor the death penalty tend to move away from it.

   In another study that sheds light on the public's view of the death penalty's deterrent abilities, Ellsworth and Ross mailed...