Does the Death Penalty Deter Crime? Evidence Examined

Introduction

In a 1997 speech, Governor George Pataki of New York State declared the death penalty the cure to New York's ills. He echoed the arguments of death penalty supporters, stating that within one year after the reinstatement of the death penalty, violent crime rates dropped dramatically. This compelling speech reflects the voices of other death penalty supporters who claim that capital punishment is a deterrent to violent crime. These claims are based on sociological studies that suggest a connection between the death penalty and lower crime rates. However, more recently these studies have come under scrutiny, making way for a new generation of research that fails to support the death penalty as a deterrent. The following analysis examines both sides of the issue in order to determine whether the death penalty is a deterrent to crime, or merely another waste of taxpayer money.

Following Governor Pataki's impassioned speech, a series of research studies were launched that collectively supported New York's decision to reinstate the death penalty. However, the argument over the death penalty does not affect only New York — it inflames passions in every state in the union. Concerns over the results of studies supporting the death penalty stem from technical flaws and conceptual errors in their design. One of the key errors in these studies was that researchers failed to account for all relevant factors that drive murder rates. This type of error makes it difficult to determine causal relationships. Therefore, a majority of the studies must be considered inconclusive, despite their claims to the contrary.

According to the U.S. Bureau of Justice Statistics, the murder rate remained almost unchanged from 2001 to 2002. In these crimes, the race of victims was split 49% white and 49% black; however, victims in death penalty cases were nearly 81% white. In 76% of all murder cases, the victims knew their offenders, and arguments were the most commonly cited circumstance leading to the murder. These statistics do not support the effectiveness of the death penalty as a deterrent. The argument that the death penalty deters crime assumes that the person committing the crime is in a rational state of mind in which they can consider the consequences of their actions. When two people are engaged in an argument, they are seldom rational — they often say and do things they later regret, including commit murder. That is the nature of a crime of passion.

When one turns from sociological studies to econometric models, the results on the effectiveness of the death penalty as a deterrent to murder are mixed. Both sides of the debate can be accused of citing studies that support their particular point of view while ignoring evidence to the contrary. Regardless of one's opinion, it is important to examine the various studies critically. As noted above, sociological studies failed to account for confounding variables that render their results inconclusive. Some researchers claim that econometrics provides a more solid framework for studying an issue that involves many variables. Several research models are examined below.

Comparative Studies

This controversial issue can be approached from several distinct academic standpoints. The comparative research approach compares crime statistics of states that have the death penalty with those that do not. Comparative studies consistently demonstrate that the death penalty has little or no effect on preventing murders. One of the most famous of these studies was conducted by Sellin at the American Law Institute in Philadelphia. This study retains its credibility due to its reproducibility — new data can be applied to the same framework to verify the results.

Sellin compared the murder rates of Texas, California, and New York. Texas had the highest number of executions at that time; California had executed ten individuals; and New York did not have the death penalty at that time. Sellin concluded that the death penalty had little effect on deterring crime. Archer and Gartner examined fourteen countries that chose to eliminate the death penalty and found that homicide rates in those countries did not rise — an outcome that would be expected if the death penalty were truly a deterrent. The findings of Fessenden (2000) support these conclusions as well.

Econometric Studies

Comparative studies derive their credibility from the consistency of their results. Econometric methods, by contrast, fail to produce consistent results. Supporters of the death penalty can find a large number of econometric studies to support their position. The quandary is how such different results can be achieved on the same topic. Either the death penalty deters murder or it does not — both conclusions cannot realistically be correct. Sorting out conflicting results from varied study methods is difficult when one examines econometric research.

One of the key problems with econometric studies is that they rely on a sufficient volume of data to eliminate potential biases. However, there is relatively little data available on which to perform a regression analysis of the death penalty. Too little data, combined with too many ways to manipulate that data, creates significant challenges. It is difficult to construct an econometric model that includes all relevant variables with the proper weight assigned to each. The omission of variables, or the over-emphasis of one variable relative to another, can significantly skew the results.

Econometrics works best when all variables except the one being studied are held constant. In the real world, this is difficult to achieve, and this limitation accounts for many of the differences seen across econometric models. For instance, Texas has more executions per year than any other state. According to Goertzel, Texas accounts for half of all executions in the United States. Including Texas in a data set can therefore significantly skew the results. Econometric studies are most often cited by supporters of the death penalty because of their general acceptance in other research fields. There are a number of econometric studies that support a connection between executions and drops in homicide rates. However, as demonstrated above, econometric studies may not provide the most accurate picture of the effects of the death penalty on crime.

Conclusion

In order to support the death penalty as a deterrent to crime, one would have to find definitive evidence that the death penalty does indeed deter crime. However, the numbers used to report murder rates only tell us the number of crimes that have occurred. They tell us nothing about crimes that were never committed because of fear of the death penalty. The fundamental problem is that there is no realistic way to measure something that did not happen in the general population, at least not in a manner that would be credible from a scientific standpoint.

Those who support the death penalty tend to place greater emphasis on the credibility of econometric methods of analysis and can find many studies within that body of work to support their position. They discredit comparative methods of study that do not support their view. Both proponents and opponents have attempted to reduce the debate over whether the death penalty deters murder to a question of methodological credibility. This argument, however, fails — there are flaws in all of the methodologies used to study the issue to date. In some cases, it would appear that the death penalty actually increases the murder rate, as seen in the Southern states. Many of the studies reviewed suffered from attempting to make inferences and draw causal relationships when too many variables were left unaccounted for. They are inconclusive at best and therefore cannot tell us anything definitive about the connection between the death penalty and trends in murder rates.

This finding might appear to leave the original research question unanswerable. However, that is only true if one falls into what might be called the credibility trap — the assumption that some studies are so methodologically superior that they resolve the debate. Some studies may indeed be more credible than others, but this still does not mean they provide an authoritative answer. There is simply too much conflicting evidence to decide whether the death penalty does or does not deter crime. Those who support the death penalty do so on the basis of a selective number of research studies that claim a causal connection between drops in crime rates and the practice of capital punishment. However, as demonstrated throughout this analysis, many of these studies were flawed due to the inability to isolate the dependent variable. This does not mean their findings are necessarily inaccurate — it simply means they are inconclusive. Proponents of the death penalty cannot definitively prove that it deters crime.

On the other hand, opponents cannot disprove a causal relationship either. However, the burden of proof does not rest with them. If they can discredit the opposing argument by presenting conflicting results and inconclusive evidence, then their argument is supported by default. The original research question was whether the death penalty acts as a deterrent to murder. Considering the lack of positive proof, the answer must favor those who say it does not. One could therefore support the position that, due to a lack of substantial evidence that the death penalty deters crime, the practice of capital punishment warrants reconsideration in favor of less severe forms of punishment. Those who oppose the death penalty debate do so based on a lack of evidence that it deters crime. This argument is logically sound, even in light of the absence of contrary evidence.

Works Cited

Archer, D. and Gartner, R. (1984). Homicide and the death penalty: A cross-national test of a deterrence hypothesis. In Archer and Gartner, Violence and Crime in Cross-National Perspective. New Haven: Yale University Press.

Dezhbaksh, H., Robin, P., and Shepherd, J. (2002). Does capital punishment have a deterrent effect? New evidence from post-moratorium panel data. American Law and Economics Review 5(2): 344–376.

Fagan, J. (2005). Deterrence and the death penalty: A critical review of new evidence. Testimony to the New York State Assembly Standing Committee on Codes. Columbia Law School. January 21, 2005.

FBI (2003). Uniform Crime Reports. Released June 16, 2003.

Fessenden, F. (2000). Deadly statistics: A survey of crime and punishment. The New York Times, September 22, 2000.

Goertzel, T. (2004). Capital punishment and homicide: Sociological realities and econometric illusions. Skeptical Inquirer, July 2004.

Mocan, N. and Gittings, K. (2001). Pardons, executions and homicide. Working Paper 8639, National Bureau of Economic Research.

Pataki, G. (1997). Capital punishment gives killers good cause to fear arrest and conviction. USA Today, March 1997.

Sellin, T. (1959). The Death Penalty. American Law Institute, Philadelphia.

Sorenson, J., Wrinkle, R., Brewer, V., and Marquart, J. (1999). Capital punishment and deterrence: Examining the effect of executions on murder in Texas. Crime and Delinquency 45: 481–493.

U.S. Bureau of Justice Statistics (2003). Criminal Victimization, 2003.