Econometric Estimates of Deterrence of the Death Penalty: Facts or Ideology?

In 2007, the Wall Street Journal published an article claiming that each execution saves more than 70 lives. This example is used to show how easy it is, using simple or advanced econometric techniques, to produce results that do or do not support the deterrence hypothesis. Moreover, we also point to some puzzles which have not been satisfactorily solved so far. We then present a critical survey of the papers published in the last ten years. It is shown how simple changes can produce quite different results using the same data. Finally, we draw some conclusions about the usefulness of statistical arguments in policy debates, but also on the moral questions involved in this particular debate

The Deterrent Effect of Capital Punishment: Evidence from a "Judicial Experiment"

Does capital punishment deter capital crimes? We use panel data covering the fifty states duringthe period 1960-2000 period to examine the issue. Our study is novel in four ways. First, we estimate the moratorium's full effect by using both pre- and postmoratorium evidence. Second, we exploit the moratorium as a judicial experiment to measure criminals' responsiveness to the severity of punishment; we compare murder rates immediately before and after changes in states' death penalty laws. The inference draws on the variations in the timing and duration of the moratorium across states provide a cross section of murder rate changes occurring in various time periods. Third, we supplement the before-and-after comparisons with regression analysis that disentangles the impact of the moratorium itself on murder from the effect on murder of actual executions. By using two different approaches, we avoid many of the modeling criticisms of earlier studies. Fourth, in addition to estimating 84 distinct regression models - with variations in regressors, estimation method, and functional form - our robustness checks examine the moratorium's impact on crimes that are not punishable by death. Our results indicate that capital punishment has a deterrent effect, and the moratorium and executions deter murders in distinct ways. This evidence is corroborated by both the before-and-after comparisons and regression analysis. We also confirm that the moratorium and executions do not cause similar changes in non-capital crimes. The results are highly robust.

The Deterrent Effect of Capital Punishment: Evidence from a "Judicial Experiment"

We use panel data for 50 states during the 1960--2000 period to examine the deterrent effect of capital punishment, using the moratorium as a "judicial experiment." We compare murder rates immediately before and after changes in states' death penalty laws, drawing on cross-state variations in the timing and duration of the moratorium. The regression analysis supplementing the before-and-after comparisons disentangles the effect of lifting the moratorium on murder from the effect of actual executions on murder. Results suggest that capital punishment has a deterrent effect, and that executions have a distinct effect which compounds the deterrent effect of merely (re)instating the death penalty. The finding is robust across 96 regression models. (JEL C1, K1) Copyright 2006, Oxford University Press.