Brett Parker - Death Penalty Statutes and Murder Rates: Evidence from Synthetic Controls

Public debates over the death penalty in the U.S. have long focused on the punishment’s putative deterrent effect. Unsurprisingly, numerous scholars have sought to determine (a) whether the penalty in fact prevents murders, and (b) how many murders it prevents. However, these efforts have deployed a fairly homogeneous set of methodological techniques—primarily OLS and two-stage OLS with instrumental variables. This article breaks from that tradition by using synthetic controls to assess the deterrent capacity of capital punishment. Applying this technique using seven states that recently abolished the death penalty and twenty-nine states that retained the punishment during the same period, I find no evidence that the presence of a capital punishment statute in a state is sufficient to deter murders. These results are robust to numerous alternative specifications; they also persist when I use stranger homicides—which are theoretically more susceptible to deterrence—as the dependent variable.