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The essay shows that the new deterrence studies are fraught with numerous technical and conceptual errors: inappropriate methods of statistical analysis, failures to consider several relevant factors that drive murder rates such as drug epidemics, missing data on key variables in key states, the tyranny of a few outlier states and years, weak to non-existent tests of concurrent effects of incarceration, statistical confounding of murder rates with death sentences, failure to consider the general performance of the criminal justice system, artifactual results from truncated time frames, and the absence of any direct test of the components of contemporary theoretical constructions of deterrence. Social scientists have failed to replicate several of these studies, and in some cases have produced contradictory or unstable results with the same data, suggesting that the original findings are unreliable and perhaps inaccurate. The central mistake in this enterprise is one of causal reasoning: the attempt to draw causal inferences from a flawed and limited set of observational data, and the failure to address important competing influences on murder. Murder is a complex and multiply-determined phenomenon, with cyclical patterns for over forty years of distinct periods of increase and decline that are not unlike epidemics of contagious diseases. There is no reliable, scientifically sound evidence that pits execution against a robust set of competing explanations to identify whether it can exert a deterrent effect that is uniquely and sufficiently powerful to overwhelm these consistent and recurring epidemic patterns. These flaws and omissions in a body of scientific evidence render it unreliable as a basis for law or policy that generate life-and-death decisions. To accept it uncritically invites errors that have the most severe human costs.


Criminal Law | Criminal Procedure | Law | Law Enforcement and Corrections