Death Penalty Really Does Work as a Deterrent?

[Lemur]

I find this counter-intuitive, and I'm certainly going to want to do more reading before accepting it at face value, but a series of studies have shown that there is a statistically significant relationship between use of the death penalty and reduction of homicides. I toss this bloody chum into the churning waters of the Backroom. You're welcome.

Studies say death penalty deters crime

By ROBERT TANNER, AP National Writer Mon Jun 11, 4:53 AM ET

Anti-death penalty forces have gained momentum in the past few years, with a moratorium in Illinois, court disputes over lethal injection in more than a half-dozen states and progress toward outright abolishment in New Jersey.

The steady drumbeat of DNA exonerations — pointing out flaws in the justice system — has weighed against capital punishment. The moral opposition is loud, too, echoed in Europe and the rest of the industrialized world, where all but a few countries banned executions years ago.

What gets little notice, however, is a series of academic studies over the last half-dozen years that claim to settle a once hotly debated argument — whether the death penalty acts as a deterrent to murder. The analyses say yes. They count between three and 18 lives that would be saved by the execution of each convicted killer.

The reports have horrified death penalty opponents and several scientists, who vigorously question the data and its implications.

So far, the studies have had little impact on public policy. New Jersey's commission on the death penalty this year dismissed the body of knowledge on deterrence as "inconclusive."

But the ferocious argument in academic circles could eventually spread to a wider audience, as it has in the past.

"Science does really draw a conclusion. It did. There is no question about it," said Naci Mocan, an economics professor at the University of Colorado at Denver. "The conclusion is there is a deterrent effect."

A 2003 study he co-authored, and a 2006 study that re-examined the data, found that each execution results in five fewer homicides, and commuting a death sentence means five more homicides. "The results are robust, they don't really go away," he said. "I oppose the death penalty. But my results show that the death penalty (deters) — what am I going to do, hide them?"

Statistical studies like his are among a dozen papers since 2001 that capital punishment has deterrent effects. They all explore the same basic theory — if the cost of something (be it the purchase of an apple or the act of killing someone) becomes too high, people will change their behavior (forego apples or shy from murder).

To explore the question, they look at executions and homicides, by year and by state or county, trying to tease out the impact of the death penalty on homicides by accounting for other factors, such as unemployment data and per capita income, the probabilities of arrest and conviction, and more.

Among the conclusions:

• Each execution deters an average of 18 murders, according to a 2003 nationwide study by professors at Emory University. (Other studies have estimated the deterred murders per execution at three, five and 14).

• The Illinois moratorium on executions in 2000 led to 150 additional homicides over four years following, according to a 2006 study by professors at the University of Houston.

• Speeding up executions would strengthen the deterrent effect. For every 2.75 years cut from time spent on death row, one murder would be prevented, according to a 2004 study by an Emory University professor.

In 2005, there were 16,692 cases of murder and nonnegligent manslaughter nationally. There were 60 executions.

The studies' conclusions drew a philosophical response from a well-known liberal law professor, University of Chicago's Cass Sunstein. A critic of the death penalty, in 2005 he co-authored a paper titled "Is capital punishment morally required?"

"If it's the case that executing murderers prevents the execution of innocents by murderers, then the moral evaluation is not simple," he told The Associated Press. "Abolitionists or others, like me, who are skeptical about the death penalty haven't given adequate consideration to the possibility that innocent life is saved by the death penalty."

Sunstein said that moral questions aside, the data needs more study.

Critics of the findings have been vociferous.

Some claim that the pro-deterrent studies made profound mistakes in their methodology, so their results are untrustworthy. Another critic argues that the studies wrongly count all homicides, rather than just those homicides where a conviction could bring the death penalty. And several argue that there are simply too few executions each year in the United States to make a judgment.

"We just don't have enough data to say anything," said Justin Wolfers, an economist at the Wharton School of Business who last year co-authored a sweeping critique of several studies, and said they were "flimsy" and appeared in "second-tier journals."

"This isn't left vs. right. This is a nerdy statistician saying it's too hard to tell," Wolfers said. "Within the advocacy community and legal scholars who are not as statistically adept, they will tell you it's still an open question. Among the small number of economists at leading universities whose bread and butter is statistical analysis, the argument is finished."

Several authors of the pro-deterrent reports said they welcome criticism in the interests of science, but said their work is being attacked by opponents of capital punishment for their findings, not their flaws.

"Instead of people sitting down and saying 'let's see what the data shows,' it's people sitting down and saying 'let's show this is wrong,'" said Paul Rubin, an economist and co-author of an Emory University study. "Some scientists are out seeking the truth, and some of them have a position they would like to defend."

The latest arguments replay a 1970s debate that had an impact far beyond academic circles.

Then, economist Isaac Ehrlich had also concluded that executions deterred future crimes. His 1975 report was the subject of mainstream news articles and public debate, and was cited in papers before the
U.S. Supreme Court arguing for a reversal of the court's 1972 suspension of executions. (The court, in 1976, reinstated the death penalty.)

Ultimately, a panel was set up by the
National Academy of Sciences which decided that Ehrlich's conclusions were flawed. But the new pro-deterrent studies haven't gotten that kind of scrutiny.

At least not yet. The academic debate, and the larger national argument about the death penalty itself — with questions about racial and economic disparities in its implementation — shows no signs of fading away.

Steven Shavell, a professor of law and economics at Harvard Law School and co-editor-in-chief of the American Law and Economics Review, said in an e-mail exchange that his journal intends to publish several articles on the statistical studies on deterrence in an upcoming issue.

[Xiahou]

I saw this study too... interesting. Personally, I've always felt the death penalty should be used very rarely and cautiously, but I don't think it would be wise to take off the table altogether. Even still, as long as it's decided democratically, state-by-state, (as opposed to judicial fiat) I can live with either.

Here's something in the article that earns a resounding "no-duh" from me:

Speeding up executions would strengthen the deterrent effect.

Of course it would. But, on the flip side, the quicker the executions come, the more likely we are to see an innocent person executed.

[Kekvit Irae]

Personally, I believe it does. I'd much rather see a serial rapist or murderer get the chair than seeing him in prison for the rest of his life (and given almost as many rights as a normal US citizen).

[Proletariat]

I don't think it really matters if it's a deterrent or not. I always think of the death penalty as justice being implemented, not vengeance or a 'warning to others'

[Hosakawa Tito]

It certainly guarantees that the perp won't kill again. However, I would require that significant DNA evidence tie the accused to the crime. Eye witness evidence alone is way too unreliable and subject to human error, bias, and fallibility.

The killing doesn't stop once killers are in jail either. The victims just change to other inmates and prison staff. What's the deterrent to the already incarcerated homicidally inclined ? Whatcha gonna do C.O., throw me in jail?
A visit to old Sparky is in order. How do you like your justice, regular or extra crispy? The Donna Payant Story

[Kralizec]

I'm not sure wether the death penalty should be considered just (except for people like Milosovic and Charles Taylor) but I don't think deterrence has any relevance for determining its justice value. Saying someone deserves the death penalty is one thing, but making an example for the sake of making an example is never just.

[Proletariat]

If I wasn't clear, ^^^ is what I meant to say.



Edit: Well pointed out flaw in the 'life sentence is harsher than death' argument that comes up in these debates once in awhile from the anti-death penalty side, Hosa.

Edit2: Wow, chilling story.

[Rodion Romanovich]

I would require that significant DNA evidence tie the accused to the crime. Eye witness evidence alone is way too unreliable and subject to human error, bias, and fallibility.

Unfortunately, DNA evidence is also subject to error, bias and fallibility. It's not very difficult to plant DNA evidence, in fact human beings lose about 40 hairs a day, which are easy to pick up and plant on a victim.

The killing doesn't stop once killers are in jail either. The victims just change to other inmates and prison staff.

Lack of prison security is a problem in itself, not a justification for death penalty. Prison security must be solved anyway, because there will always be inmates who are in jail because they're poor and couldn't pay a fine, or wrongfully accused people. It's the duty of the state to protect these from danger when their freedom and liberty is temporarily stolen in the name of justice.

[Banquo's Ghost]

Most members know that I am implacably opposed to the death penalty, but the information posted bears reflection.

The deterrent effect of capital punishment is very tough to measure (in the same sense as measuring any decision-making process that leads to crime) but one objection I would be interested in exploring is the historical one.

Up until the middle of the nineteenth century, Europe (and especially the UK) executed enormous numbers of people for comparatively trivial crimes such as stealing. Yet this draconian regime did not ensure crime was at a low level during those times. (Clearly, we cannot easily gauge what the crime level would have been without the hangings, but when almost any crime might get one hanged, one would have thought people would have considered committing an offense a very poor life choice. This may be mirrored in modern China, where capital punishment is applied for a much wider range of crimes than murder, and yet criminals do not appear to be deterred).

Whilst there are obviously variables such as the dire consequences of poverty (in itself a death sentence in many cases) and the much lower likelihood of being caught, I'd be interested in views on why such brutal applications of the death penalty did not drastically reduce offending.

[Rodion Romanovich]

I find this counter-intuitive, and I'm certainly going to want to do more reading before accepting it at face value, but a series of studies have shown that there is a statistically significant relationship between use of the death penalty and reduction of homicides. I toss this bloody chum into the churning waters of the Backroom. You're welcome.

Studies say death penalty deters crime

By ROBERT TANNER, AP National Writer Mon Jun 11, 4:53 AM ET

Anti-death penalty forces have gained momentum in the past few years, with a moratorium in Illinois, court disputes over lethal injection in more than a half-dozen states and progress toward outright abolishment in New Jersey.

The steady drumbeat of DNA exonerations — pointing out flaws in the justice system — has weighed against capital punishment. The moral opposition is loud, too, echoed in Europe and the rest of the industrialized world, where all but a few countries banned executions years ago.

What gets little notice, however, is a series of academic studies over the last half-dozen years that claim to settle a once hotly debated argument — whether the death penalty acts as a deterrent to murder. The analyses say yes. They count between three and 18 lives that would be saved by the execution of each convicted killer.

The reports have horrified death penalty opponents and several scientists, who vigorously question the data and its implications.

So far, the studies have had little impact on public policy. New Jersey's commission on the death penalty this year dismissed the body of knowledge on deterrence as "inconclusive."

But the ferocious argument in academic circles could eventually spread to a wider audience, as it has in the past.

"Science does really draw a conclusion. It did. There is no question about it," said Naci Mocan, an economics professor at the University of Colorado at Denver. "The conclusion is there is a deterrent effect."

A 2003 study he co-authored, and a 2006 study that re-examined the data, found that each execution results in five fewer homicides, and commuting a death sentence means five more homicides. "The results are robust, they don't really go away," he said. "I oppose the death penalty. But my results show that the death penalty (deters) — what am I going to do, hide them?"

Statistical studies like his are among a dozen papers since 2001 that capital punishment has deterrent effects. They all explore the same basic theory — if the cost of something (be it the purchase of an apple or the act of killing someone) becomes too high, people will change their behavior (forego apples or shy from murder).

To explore the question, they look at executions and homicides, by year and by state or county, trying to tease out the impact of the death penalty on homicides by accounting for other factors, such as unemployment data and per capita income, the probabilities of arrest and conviction, and more.

Among the conclusions:

• Each execution deters an average of 18 murders, according to a 2003 nationwide study by professors at Emory University. (Other studies have estimated the deterred murders per execution at three, five and 14).

• The Illinois moratorium on executions in 2000 led to 150 additional homicides over four years following, according to a 2006 study by professors at the University of Houston.

• Speeding up executions would strengthen the deterrent effect. For every 2.75 years cut from time spent on death row, one murder would be prevented, according to a 2004 study by an Emory University professor.

In 2005, there were 16,692 cases of murder and nonnegligent manslaughter nationally. There were 60 executions.

The studies' conclusions drew a philosophical response from a well-known liberal law professor, University of Chicago's Cass Sunstein. A critic of the death penalty, in 2005 he co-authored a paper titled "Is capital punishment morally required?"

"If it's the case that executing murderers prevents the execution of innocents by murderers, then the moral evaluation is not simple," he told The Associated Press. "Abolitionists or others, like me, who are skeptical about the death penalty haven't given adequate consideration to the possibility that innocent life is saved by the death penalty."

Sunstein said that moral questions aside, the data needs more study.

Critics of the findings have been vociferous.

Some claim that the pro-deterrent studies made profound mistakes in their methodology, so their results are untrustworthy. Another critic argues that the studies wrongly count all homicides, rather than just those homicides where a conviction could bring the death penalty. And several argue that there are simply too few executions each year in the United States to make a judgment.

"We just don't have enough data to say anything," said Justin Wolfers, an economist at the Wharton School of Business who last year co-authored a sweeping critique of several studies, and said they were "flimsy" and appeared in "second-tier journals."

"This isn't left vs. right. This is a nerdy statistician saying it's too hard to tell," Wolfers said. "Within the advocacy community and legal scholars who are not as statistically adept, they will tell you it's still an open question. Among the small number of economists at leading universities whose bread and butter is statistical analysis, the argument is finished."

Several authors of the pro-deterrent reports said they welcome criticism in the interests of science, but said their work is being attacked by opponents of capital punishment for their findings, not their flaws.

"Instead of people sitting down and saying 'let's see what the data shows,' it's people sitting down and saying 'let's show this is wrong,'" said Paul Rubin, an economist and co-author of an Emory University study. "Some scientists are out seeking the truth, and some of them have a position they would like to defend."

The latest arguments replay a 1970s debate that had an impact far beyond academic circles.

Then, economist Isaac Ehrlich had also concluded that executions deterred future crimes. His 1975 report was the subject of mainstream news articles and public debate, and was cited in papers before the
U.S. Supreme Court arguing for a reversal of the court's 1972 suspension of executions. (The court, in 1976, reinstated the death penalty.)

Ultimately, a panel was set up by the
National Academy of Sciences which decided that Ehrlich's conclusions were flawed. But the new pro-deterrent studies haven't gotten that kind of scrutiny.

At least not yet. The academic debate, and the larger national argument about the death penalty itself — with questions about racial and economic disparities in its implementation — shows no signs of fading away.

Steven Shavell, a professor of law and economics at Harvard Law School and co-editor-in-chief of the American Law and Economics Review, said in an e-mail exchange that his journal intends to publish several articles on the statistical studies on deterrence in an upcoming issue.

Seemed interesting at first, then I noticed a major fallacy, in that these studies are done exclusively in the USA, not comparing the results with other countries, and they are also restricted to a short period; only the most recent 5-10 years of history. What we may draw as a conclusion is that in the last 5-10 years, only in America, there is a correlation between death penalty and reduced homicide. The lack of greater time and geography perspective means there's not any material to suggest a causality. In fact, the USA and China, notorious death penalty nations, quite conveniently have the most homicides in the world.

Edit: thanks Ironside, that's the type of data I mean