No credible evidence shows the death penalty deters homicide

Evidence

Despite improved analytic methods, the key issue of whether executions deter homicides more effectively than lifetime imprisonment without parole remains unsettled. Given the insufficient and equivocal quality of the data, claims that each execution saves a specified number of lives are highly questionable. The law professors John J. Donohue and Justin Wolfers described the difficulty of isolating a deterrent effect caused by a few executions within a mix of many other factors that influence murder rates. The penalty “is applied so rarely that the number of homicides it can plausibly have caused or deterred cannot reliably be disentangled from the large year-to-year changes in the homicide rate caused by other factors” (Liptak, 2007). Professor John Lamperti (1996) put it more succinctly: “The signal, if any, is hopelessly buried in the noise.” Liptak (2007) describes a deep disciplinary divide in this field. Econometricians, acting on the tenet that if you raise costs of an activity its use will decline, often claim deterrent effects. By contrast criminologists, who question the appropriateness of economic theory as a research method on violent crimes, find no credible evidence that murders are deterred by the threat of the death penalty. … In sum, there is no consistent evidence that the death penalty deters would-be murderers (Fagan, 2006). In a comprehensive review of research on the effect of the death penalty, a committee of the National Research Council concluded that much of the research is flawed and provides no informative evidence of a deterrent effect (Nagin & Pepper, 2012). The report cautions against using unreliable findings as a basis for policies regarding capital punishment. — Albert Bandura, Moral Disengagement, 1952

Categorization

• XREF: Economists and criminologists split over death penalty deterrence; echoes the law-and-economics vs. sociology-of-Deviance division seen in the Milgrom law-merchant material.
• ADDENDUM: Could bolster the ‘sacrifice as stabilizer’ essay: the death penalty as ritual harm sustained despite no deterrent evidence.