Capital punishment and recidivism

Greg Mankiw writes,

Cass Sunstein and Justin Wolfers say we don’t really know whether or not capital punishment deters crime.

Maybe so, but it does solve the problem of recidivism.

He links to a news article that refers to an excellent article by Wolfers and Donohue. But I don’t think Mankiw is correct about capital punishment solving recidivism. A key aspect of the death penalty in the U.S. is how rare it is for prisoners to actually be executed. I don’t see how you solve the problem of recidivism by executing on the order of a hundred people a year. And, given that already our best estimate is that a person who is sentenced to death has a two-thirds chance of having that sentence reversed by a higher court, it’s hard for me to believe that the rate of executions can be increased very much.

11 thoughts on “Capital punishment and recidivism

  1. Relative to life in prison without the possibility of parole, it has no incremental effect on recidivism at all.

  2. I think people who say that know what you mean, they just enjoy making a nasty joke. So it would be a mistake to spend too much effort explaining their "error".

  3. The argument is that it doesn't stop recidivism if you don't actually do it? That makes sense. It applies to most policies: if you do not carry out the policy, its effects are very small. Similarly, litter clean-up policies only tend to reduce litter in the areas you clean up. If you only clean 100 spots per year, the effect on total litter will be small. But those 100 spots are cleaner. (This is not to compare human life to litter. It is just the first example of a spottily applied practice that came to mind.)

    Contradicting an earlier commenter, life in prison retains the possibility of recidivism. You can commit crimes against other prisoners. There is plenty of that on record. There are no cases on record, to my knowledge, of an executed person going on to commit later offenses. I think that is a fair and true reading of Greg Mankiw's comment. And yes, it is gallows humor.

  4. I recall a study on inmates who were removed from death row in the wake of Furman. Some of these prisoners were eventually released (paroled) as were some of those who had been sentenced to life rather than execution. A comparison of these two groups showed no difference in recidivism for serious crimes, and in both groups, such recidivism was small. (Sorry, but I don't have the reference right now.)

  5. Zubon,

    Exactly. Executing 100 people a year might deter (as noted, the evidence on this could go either way), but there's no way it will "solve the problem of recidivism." You're talking about a very small percentage of cases.

    Derek, ZB,

    Yes, I had assumed it was a joke. But as a statistician, I'm often inclined to analyze jokes quantitatively (just as Mankiw might, I suppose, if he were to encounter an offhand joke about "supply and demand" or some other concept from economics).

  6. Recidivism, as typically used, refers to behavior after completing the prison term, or, in the case of substance abuse programs, after completing the treatment program. So I pedantically stick to my initial comment!

    Wasn't there a study done a while ago (JASA, IIRC, and other forums no doubt) that showed that murder rates spiked slightly 2-3 days after an execution?

  7. This argument is obviously tongue in cheek, but opponents of the death penalty cannot honestly claim that the low rate of executions and the slowness of the process is a downside of the system: it is those very opponents who slow up the system.

    Opponents of the death penalty also continuously fail to recognize that leaving murderers alive, even if in jail, guarantees that more innocents are killed. Murderers in prison kill prison guards, kill other inmates and order hits from inside prison.

  8. There are some problems with:

    A Death Penalty Puzzle: The Murky Evidence for and Against Deterrence (Washington Post, By Cass R. Sunstein and Justin Wolfers, June 30, 2008; Page A11 )

    The article states: "But that suggestion (of the many recent studies finding for deterrence) actually catalyzed Donohue and Wolfers's study of available empirical evidence. Existing studies contain significant statistical errors, and slightly different approaches yield widely varying findings, a problem exacerbated by researchers' tendency to report only those results supporting their conclusions."

    REPLY: ". . . researchers' tendency to report only those results supporting their conclusions."! My goodness, this seems much like the pot calling the kettle black. Please see the four replies to Donahue and Wolfers, at bottom – replies which, collectively, appear to lay waste to Donahue and Wolfers criticism. It should also be pointed out that Donahue and Wolfers chose not to publish their criticism in a peer reviewed publication.

    The article continues: "In short, the best reading of the accumulated data is that they do not establish a deterrent effect of the death penalty."

    REPLY: I think it is arguable that is an unfair reading of the data.

    My take is that it would be more accurate to state that the social science of determining the measurable effect of general deterrence is challenging, at best. The strength of the recent econometric studies is suggestive of a deterrent effect of the death penalty and the criticism of those studies seems much less robust than the studies, themselves.

    In general terms, the weight of the evidence is that all prospects for a negative outcome deter some. There appears to be few, if any, exceptions to that rule.

    The article continues: "But as executions resume, the debates over the death penalty should not be distorted by a misunderstanding of what the evidence actually shows."

    REPLY: Again, it appears that misunderstanding is, precisely, what this newest article was distributing, however unintended.

    The article continues: "A prominent line of reasoning, endorsed by several justices, holds that if capital punishment fails to deter crime, it serves no useful purpose and hence is cruel and unusual, violating the Eighth Amendment." "While some favor the death penalty on retributive grounds, many others (including President Bush) argue that the only sound reason for capital punishment is to deter murder."

    REPLY: The lack of balance or understanding by S&W appears quite robust. There are many well defined reasons for criminal sanction, outside of deterrence. Retribution, justice, upholding the social contract, incapacitation, among others. Obviously, capital punishment does not violate the Eight Amendment, as both the 5th and 14th Amendments assert the constitutionality of the death penalty. These are well known and important facts, not in S&W's article.

    Both the current Pres. Bush and former VP Al Gore stated they support the death penalty because of deterrence. However, it is important to clarify. Does anyone believe that either Gore of Bush would support the execution of someone if it wasn't deserved? I suggest the answer is no. It's a fair question. Ask them. Then ask them, if the death penalty did not deter like men as Bib Laden or Hitler, would you still support their executions? Does anyone not know their answer? Of course not.

    The article continues: "We concur with Scalia that if a strong deterrent effect could be demonstrated, a plausible argument could be made on behalf of executions. But what if the evidence is inconclusive?"

    REPLY: Inconclusive? The weight of the evidence is that some are deterred by any prospect of a negative outcome. But, let's project an imaginary world where the evidence is completely neutral on the effects of negative prospects, where there is no evidence of what incentives mean to behavior.

    We have two equally balanced prospects. The death penalty/executions deter and the death penalty/executions don't deter.

    This prospect is neither inconclusive or equally balanced, because you have a prospect between sparing innocent life, via death penalty/execution deterrence or a prospect of death penalty/execution, with no deterrence, but enhanced incapacitation.

    If deterrence is inconclusive, the prospect of saving innocent lives is not.

    In addition, the deterrence calculus becomes- we execute and save additional innocent lives (via deterrence) or we execute and don't save additional innocent lives (via deterrence). The weight falls upon saving additional lives, if we have inconclusive data, because the weight is greater for saving additional innocent lives than on not saving additional innocent lives.

    With this type of calculus, the only argument for not executing is if the evidence is clear that the death penalty/execution is sacrificing more innocents, via brutalization – the prospect that by executing, you are inspiring potential murderers to become real murderers. Brutalization is discounted because the evidence for deterrence is much more robust and the practical evidence that crimes will increase because of raised sanction doesn't exist.

    As noted, there are a number of good reasons to argue in favor of the death penalty, other than deterrence. Even if the death penalty is a very marginal deterrent, it is still a robust argument in favor of the sanction.

    Let's say that every four executions deters one potential murderer and every twenty death sentences deters one potential murderer. That would mean that around 650 innocents had been spared since 1973. Even marginal deterrence equals major benefit.

    This does not take into account the two other ways that the death penalty saves additional innocent lives. Enhanced incapacitation and enhanced due process.

    Sincerely, Dudley Sharp


    four replies to Donahue and Wolfers

    Hashem Dezhbakhsh & Paul H. Rubin
    From the 'Econometrics of Capital Punishment' to the 'Capital Punishment' of Econometrics: On the Use and Abuse of Sensitivity Analysis (September 2007). Emory Law and Economics Research Paper No. 07-18,

    Abstract: The academic debate over the deterrent effect of capital punishment has intensified again with a major policy outcome at stake. About two dozen empirical studies have recently emerged that explore the issue. Donohue and Wolfers (2005) claim to have examined the recent studies and shown the evidence is not robust to specification changes. We argue that the narrow scope of their study does not warrant this claim.


    (2006) "This analysis shows that ((Donohue and Wolfers' "D&W's")attempts to make the deterrence effect disappear are ineffective." (p 16)
    — Existence of the death penalty, in law, has a statistically significant impact on reducing murders. (p 23)
    — Execution rates show significant impact in reducing murders. (p 13 & 23)
    — Death row commutations, and other removals, increase murders. (p13 & 23)
    — The criticism of our studies is flawed and does not effect the strength of the measured deterrent effect.
    "The Impact of Incentives On Human Behavior: Can we Make It Disappear? The Case of the Death Penalty", Naci H. Mocan, R. Kaj Grittings, NBER Working Paper, 10/06, www(dot)

    (2006) " . . . (Donohue and Wolfers' "D&W") criticisms of Zimmerman's analysis are misrepresentative, moot or unsupportable in terms of the analyses they perform." "It is shown that Zimmerman's published empirical results, or the conclusions drawn from them, are not in any way refuted by D&W's critique." (pg 3) "This later estimate suggests that each execution deters 14 murders on average . . .". (pg 7) "It is shown that D&W made a number of serious misinterpretations in their review of Zimmerman's study and that none of the analyses put forward by D&W (which ostensibly refute Zimmerman's original results and conclusions) hold up under scrutiny. (pg8) " . . . D&W do not even report Zimmerman's "preferred" results correctly, and then proceed by carrying on this error throughout the remainder of their critique."(pg8) "Of course, (D&W's) omission tends to create a strong impression that Zimmerman's analysis 'purports to find reliable relationships between executions and homicides', when his actual conclusions regarding the deterrent effect of capital punishment are far more agnostic." (pg10) " . . . D&W's method of interpreting their results is not consistent with that proscribed by the received econometric literature on randomized testing . . .". "As such, D&W's interpretation of their randomized test in itself does not (and cannot) reasonably lead one to conclude that Zimmerman's estimates suggesting a deterrent effect of capital punishment are spurious." (pg12) " . . . D&W do not appear to have interpreted their randomization test in any meaningful fashion." (pg14) " . . . the state clustering correction employed by D&W may not be producing statistically meaningful results." (pg16) "And while D&W once lamented that recent econometric studies purporting to demonstrate a deterrent effect of capital punishment yield 'heat rather than light', as shown herein, their criticisms of Zimmerman (2004) tend to yield 'smoke rather than fire'."(pg26)
    Zimmerman, Paul R., "On the Uses and 'Abuses' of Empirical Evidence in
    the Death Penalty Debate" (November 2006). ssrn(dot)com/abstract=948424


    (2007) "Had (D&W's) paper been subjected to the normal blind peer review process in an authoritative economic journal it is highly unlikely that it would have survived intact , if at all. "

    "(D&W's) Quibbling over numerous and sometimes meaningless statistical issues obscures the picture painted by the cumulative effect of the nearly dozen studies published since the turn of the 21st century."

    "Using differing methodologies and data sets at least five groups of scholars each working independently (and often without knowledge of the others) have arrived at the same conclusion—there is significant and robust evidence that executions deter some homicides. While there may be merit in some of (D&W's) specific criticisms, none addresses the totality of the collection of studies. The probability that chance alone explains the coincidence of these virtually simultaneous conclusions is negligible."

    "DW’s unsupported claim that the appropriate variable in studies of deterrence using these borrowed tools from portfolio analysis is the amount or level of homicides in the respective jurisdictions. This claim is without theoretical basis or empirical precedent. "

    "With regard to DW’s specific comments on our two papers (Cloninger & Marchesini, 2001 & 2006) we find very little requiring defense. Implicit in their critique, and explicitly stated in private communications, DW were able to replicate our results based on data we furnished, at their request, as well as data they acquired independently. "

    "Reflections on a Critique", Dale O Cloninger and Roberto Marchesini, forthcoming Applied Economic Letters

  9. The major problem with capital punishment failing as a deterence today is two fold.

    First, it takes two to four years to get a capital case to trial. Then it takes another five to six years for the case to be reviewed by the appelate courts and all the appeals to be heard. This delay minimizes the seriousness of offender's action in the minds of the community and future offenders.

    Secondly, today the execution is carried out within the confines of a prison where the execution is viewed by prison officals and a few relatives or friends of the defendant. The real impact of capital punishment is therefore lost on both the prison inmate population and the general public.

    In the early 1900's it was a requirement of United States prisons that the entire inmate populations were to witness all executions while serving out their sentences. And fifty years earlier most executions were conducted in full view of the citizen's of the community. Imagine yourself driving by your local city hall and seeing one or two individuals swinging from ropes on a gallow. Would that scene have an impact on you? You bet it would!!!

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