Does the death penalty deter capital crimes?

To follow is an excerpt from the CQ Researcher issue "Death Penalty Debates" by Kenneth Jost on November 19, 2010

Three decades after casting the pivotal vote in the 1976 decision to uphold revised death penalty laws, Justice John Paul Stevens in 2008 urged the Supreme Court and state legislatures to reconsider the issue. Among his reasons, Stevens cited what he called the lack of “reliable statistical evidence” that capital punishment deters potential offenders. Without such evidence, Stevens wrote, “deterrence cannot serve as a sufficient penological justification for this uniquely severe and irrevocable punishment.”

Stevens' opinion — a separate concurrence in a decision that upheld the procedures for lethal injection executions — prompted a tart response from conservative Justice Antonin Scalia. He accused Stevens of ignoring what two scholars had called “the significant body” of evidence pointing to a possible deterrent effect. Regardless of the evidence, Scalia concluded, the Supreme Court has no right “to demand that state legislatures support their criminal sanctions with foolproof empirical studies, rather than commonsense predictions about human behavior.” [Footnote 5]

The question of deterrence has divided supporters and opponents of the death penalty in the United States at least since the early 19th century, according to legal historian Stuart Banner. In those days, the UCLA law professor writes, there was “a virtual absence of any attempt by either side to back up its claims with numbers.”[Footnote 6] Today, by contrast, the debate is densely statistical. Even so, more than three decades of research by economists and law professors published in two dozen or more academic articles have failed to resolve the debate.[Footnote 7]

The modern debate dates from an article published in 1975 in the American Economic Review by Isaac Ehrlich, now chairman of the economics department at the University of Buffalo and also a distinguished professor at the State University of New York. Ehrlich used data from the period 1933–1969 to conclude that each execution served on average to prevent eight murders through deterrence of other killings. As Banner relates, the article drew unaccustomed attention for a statistically technical study — followed by “intense criticism” of Ehrlich's methodology and conclusion.[Footnote 8]

Many more studies followed. By the early 2000s, supporters of capital punishment counted a total of 14 that found evidence of a deterrent effect from the death penalty. In an influential study published in 2003, Emory University economists Hashem Dezhbakhsh and Paul H. Rubin and Emory law professor Joanna Shepherd used data from before and after then-recent death penalty moratoriums to conclude that each execution prevented on average 18 murders.

Their conclusion was challenged in turn in a 2005 article by Yale law professor John Donohoe and economist Justin Wolfers of the University of Pennsylvania's Wharton School. They called the evidence for deterrence “surprisingly fragile,” noting that minor changes in methodology resulted in completely different results. In a condensed version that appeared along with an exchange with the Emory authors, Donohoe and Wolfers wrote: “The view that the death penalty deters is still the product of belief, not evidence.”[Footnote 9]

Today, the economists remain in disagreement while appearing to acknowledge the impossibility of a definitive conclusion. “There are ways to do the analyses to find deterrence and ways to do it to find no deterrence,” says Rubin. For his part, Wolfers says the presence or absence of deterrence “is difficult to tell no matter whatever angle you look at it.”

With the economists in disagreement, pro- and anti-death penalty advocates tend to side with the view that supports their position. “I think the literature as a whole still shows deterrence,” says Scheidegger with the Criminal Justice Legal Foundation. “And I think the evidence will grow stronger over time.” From the other side, Cornell's Blume says flatly, “There's no credible evidence that the death penalty is a deterrent.”

Even while supporting the death penalty, many in the law enforcement community voice doubts that killers actually weigh the potential consequences of their crimes before committing them. “Do people in emotional circumstance contemplate” the potential punishment? asks Scott Burns, executive director of the National District Attorneys Association. “Probably not.”

The search for evidence of deterrence is difficult in part because of the relative infrequency of executions in the United States. “In 99 percent of the murders, there are not going to be executions, not even a death sentence,” says Dieter with the Death Penalty Information Center.

“It's certainly an enormous waste of money in terms of deterrence,” says Streib, the Ohio Northern University professor. “There are so many other things we could do with that money.”

The Issues:
* Does the death penalty deter capital crimes?
* Does capital punishment cost more to administer than it is worth?
* Do capital defendants have adequate legal representation in court and after sentencing?

For more information see the CQ Researcher report on "Death Penalty Debates" [subscription required] or purchase the PDF

[5] The decision is Baze v. Rees, 553 U.S. 535 (2008),

[6] Stuart Banner, The Death Penalty: An American History (2002), p. 114.

[7] For a good journalistic overview of the scholarship, see Adam Liptak, “Does Death Penalty Save Lives? A New Debate,” The New York Times, Nov. 18, 2007, sec. 1, p. 1, The website version includes hyperlinks to several of the major articles. Some background drawn from article.

[8] Banner, op. cit., pp. 279–281.

[9] John Donohue and Justin J. Wolfers, “The Death Penalty: No Evidence for Deterrence,” in Joseph E. Stiglitz, et al. (eds.), The Economists' Voice: Top Economists Take On Today's Problems (2008), p. 255.