State Executions, Deterrence, and the Incidence of Murder

Abstract

This study employs a panel of state data over the years 1978-1997 to estimate the deterrent effect of the probability of apprehension, the probability of conviction given apprehension, and the probability of execution given conviction on the rate of per-capita murders. Particular attention is paid to problems of endogeneity bias arising from the non-random assignment of death penalty laws across states and a simultaneous relationship between murders and the deterrence probabilities. The primary innovation of the analysis lies in the estimation of a simultaneous equations system whose identification is based upon the employment of instrumental variables motivated by the theory of public choice as it relates to the criminal justice system and bureaucratic behavior. This is the first time such instruments have been used in the literature, and it is shown that these instruments are both statistically relevant and valid. The estimation results suggest that structural estimates of the deterrent effect of capital punishment are likely to be downward biased due to the influence of simultaneity. Correcting for simultaneity, the estimates imply that a state execution deters approximately fourteen murders per year on average.

Keywords: capital punishment, executions, deterrence, murder

JEL Classification: K42, H00