Estimates of the Deterrent Effect of Alternative Execution Methods in the United States: 1978-2000
Posted: 27 Feb 2003
Several recent econometric studies suggest that states' application of capital punishment deters the rate of murder [Brumm and Cloninger (1996), Cloninger and Marchesini (2001), Mocan and Gittings (2001), and Zimmerman (2002)]. Since the U.S. Supreme Court's moratorium on state executions was lifted in 1976, states with death penalty laws have executed individuals using one or more of five different methods of execution (electrocution, lethal injection, gas chamber asphyxiation, hanging, and/or firing squad). The perceived "brutality" of certain execution methods (such as electrocution and gas chamber asphyxiation) has also recently lead to lethal injection being imposed as the sole method of execution in several death penalty states.
Using a panel of state-level data over the years 1978-2000, this paper examines whether the method by which death penalty states conduct their executions affects the per-capita incidence of murder in a differential manner. Several measures of the subjective probability of being executed are developed taking into account the timing of individual executions as in Mocan and Gittings (2001). The empirical estimates suggest that the deterrent effect of capital punishment is driven primarily by executions conducted by electrocution. None of the other four methods of execution are found to have a statistically significant impact on the per-capita incidence of murder. These results are robust with respect to the manner in which the subjective probabilities of being executed are defined, whether or not a state has a death penalty law on the books, the removal of state and year fixed effects, controls for state-specific time trends, simultaneous control of all execution methods, and controls for other forms of public deterrence. In addition, it is shown that the negative and statistically significant impact of electrocutions is not driven by the occurrence of a "botched" electrocution execution during the relevant time period.
Keywords: executions, deterrence, methods of execution, capital punishment
JEL Classification: K42
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