Study: Tougher Prison Sentences Don't Deter Most Potential Criminals

April 22, 2004

PHILADELPHIA Just the threat of "hard time" in prison doesn't discourage most potential criminals from committing crimes, according to a study led by a University of Pennsylvania Law School professor.

The findings, published in the forthcoming Oxford Journal of Legal Studies, show that it's unproductive for legislators to re-write laws to increase prison sentences in hopes of improving the deterrence effect.

The study found that very often potential criminals don't understand laws.  

"Even if they know what the rule is, a very large percentage of offenders have limited capacity, either because they have serious drug and alcohol problems, serious mental illness or other kinds of behavioral control problems," said Paul Robinson, lead author of the study, "Does Criminal Law Deter? A Behavioral Science Investigation.  "They assume the rules are as they assume they should be."

Robinson and co-researcher John Darley of Princeton University found that many criminals don't perform a rational cost-benefit calculation, and, even if they compared the positive and negative consequences of their actions they often would choose to commit the crime.

"Potential offenders don't seriously take into account getting caught, so it doesn't matter what you're threatening to punish at the other end.  Doubling the prison sentence is not something that's going to make a difference to people who don't think they're going to get caught," Robinson said.

The researchers say increasing funding for community awareness and education programs and also increasing police patrols could be more effective than the threat of a harsh prison sentence.  

"Knowing that a police officer is driving by every 30 minutes rather than every three days could have a greater deterrent effect," Robinson said.  

The researchers say that any criminal-justice system that imposes some type of punishment for crimes will achieve a natural deterrent effect, which at best will affect only a small number of potential criminals.  

"Just try to do justice and that will carry with it probably as much deterrent effect as you're going to get," Robinson said.

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