Saturday, August 27, 2005

Prison sentences and crime 

Being an alumnus of the University of Michigan (among other fine institutions), I get regular emails summarizinng the academic work of its professors. Much of it reveals the difference in thinking between academics and everybody else. A couple of days ago the "U of M" sent me a link to this article:
Long prison sentences have minimal effects on young criminals

ANN ARBOR, Mich.—Young offenders aren't necessarily deterred from crime after they turn 18 even when they know they could be slapped with a much longer prison sentence, a new study co-authored by a University of Michigan researcher suggests....

"Our results suggest that offenders are highly impatient and impulsive people. It is hard to deter people with these characteristics from committing crime, just by threatening them with longer sentences," said David S. Lee, who, with McCrary, co-wrote "Crime, Punishment, and Myopia," which appears on the National Bureau of Economic Research website. Lee is an economics professor at the University of California-Berkeley.

Well, yeah. They can't be deterred, so that is why they must be locked up until they are old and feeble and we do not have to worry about deterring them. The authors of the study grope their way toward this conclusion, without actually reaching it (at least in the press release -- I confess that I have not read the study itself, which costs $5 online):
A natural policy implication, McCrary said, would be to spend less money on prison expansion and more money on policing. "Even with highly impatient or myopic criminals, doubling the odds of punishment will double the effective price of crime."

The press release both suggests that long prison sentences do not deter crime, but more policing, which will raise the odds of capture, will deter crime. Increased odds of a short prison sentence is better deterrance than shorter odds of a long sentence? Perhaps true, but I would be amazed if the paper actually demonstrated that.

I think we know the reason why the authors of the paper seem to have deliberately missed the critical point that prison interdicts crime. There's no social science, and therefore no career advancement, in proving that locking criminals up prevents them from committing crimes!


By Blogger geoffrobinson, at Sat Aug 27, 01:22:00 PM:

Sometimes a crimes deserves a punishment. It's not all about rehibilitation/prevention/deterrants.  

By Blogger Rob, at Sat Aug 27, 10:55:00 PM:

When I learned criminal law from Joe Goldstein (co-author of the text by Goldstein, Dershowitz & Schwartz), the relevant concept was specific deterrence. You like the guy up who commits a crime, and he's deterred for as long as he is locked up. I would like to see a study of the correlation between the long prison sentences meted out in the federal system for drug crime and the decline of crime. The federal sentences started to get stiff in 1984. I suspect crime started to see an impact by 1996 independent of economic factors.

General deterrence referred/refers to societal incentives not speicifally directed at an individual person.

Was the author of the study on the law faculty?  

By Blogger Rob, at Sat Aug 27, 10:58:00 PM:

Interestingly, the concepts of specific deterrence and general deterrence might have a feedback effect (not quite correctly phrased).

If taking enough thugs off the streets for a long time diminishes the culture that leads to crime in certain areas, the specific deterrence may lead to something like general deterrence. Not exactly general deterrence, but still a societal impact in which imprisoning A has an influence on B's likelihood to commit crime.  

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