Death penalty supporters rely on three arguments. First, that the possibility of capital punishment deters crime by increasing the expected punishment that confronts rational, forward-looking murderers. Second, that executing criminals convicted of the most serious crimes is cheaper than incarcerating them for life. Third, that murderers deserve to die.The effects of the death penalty is one of the most controversial issues in law and economics. At Freakonomics Justin Wolfers blogs on How the Supreme Court Misread My Research: Empirics and the Death Penalty. Wolfers writes
None of these arguments is persuasive. Decades of social science research finds little evidence that the death penalty deters murder. Some murderers are not forward looking (e.g., perpetrators of crimes of passion), and forward-looking murderers correctly believe their chances of being executed, even if arrested and convicted, are low and will only occur years or decades after conviction. The monetary savings from use of the death penalty are overstated, since fighting appeals from death row prisoners is costly. Moral considerations do not resolve the issue because many people believe it is wrong for the state to take a life, no matter how heinous the crime.
The death penalty, moreover, has unintended consequences. Capital punishment eliminates the possibility of correcting mistakes. This is not an enormous effect if most convicted murderers are guilty, but everyone benefits from correcting the mistakes that do occur. As with gun control, the death penalty is a distraction. Society wastes substantial energy arguing about the death penalty rather than focusing on policies that would actually reduce crime, such as ending drug prohibition, legalizing prostitution, and improving educational outcomes.
Cass Sunstein and I have an Op-Ed in today’s Washington Post, discussing the mis-reading of available empirical evidence in recent death penalty jurisprudence. Some background: A recent Supreme Court ruling (Baze v. Rees) reaffirmed the constitutionality of the death penalty, and along the way, the justices revisited the empirical literature on whether the death penalty has been shown to be an effective deterrent. Justice Stevens cited research by John Donohue and myself in concluding that “there remains no reliable statistical evidence that capital punishment in fact deters potential offenders.” Countering this, Justice Scalia cited a paper by Cass Sunstein and Adrian Vermeule, in arguing that the data do in fact point to deterrence. As two of the supposed flag bearers for the competing views cited by the court, Sunstein and I thought it worth poring over the data to see what we agree on. It turns out there’s a lot of agreement between us: “In short, the best reading of the accumulated data is that they do not establish a deterrent effect of the death penalty.”Ronald Bailey at Reason magazine asks Does It Really Matter If The Death Penalty Deters Murderers? In the article Bailey argues
The reason to retain the death penalty is vengeance, or as more polite people put it, retribution.But notes at the end of the article
... in the era of post-conviction exoneration through DNA testing, I have become much more uncomfortable about the possibility that an innocent person might be executed.This I think is the biggest problem with the death penalty, if you get it wrong there is nothing you can do about it ex post.