What is the optimal level of incarceration? An excessive rate of incarceration not only deprives individuals of freedom, but also costs taxpayers large amounts of money. Too little imprisonment harms society in a different way – through costs to victims and even non-victims who must increase precautions to avoid crime. Striking the right balance of costs and benefits is what good law and public policy strive for.
Changes to the inmate population may be made in a number of different ways and this website allows users to examine the impacts of 3 particular policies. The calculations are informed by a large amount of cutting edge research on the large array of mechanisms by which imprisonment impacts overall welfare.
To get started, choose one of the policies below to explore. You’ll have the ability to change some of the assumptions that go into the calculations. I look forward to discussing your reactions in the policy-oriented and model-oriented comments sections.
David S. Abrams
Professor of Law, Business Economics, and Public Policy
University of Pennsylvania Law School
Maybe we're not being harsh enough. Perhaps we can lower crime rates by increasing sentence lengths. Or maybe the cost savings from lowering all sentence lengths outweighs the increase in crime.Okay, let's go!
Maybe we have too many people in prison. What if we made fewer crimes punishable by prison time?Okay, let's go!
Maybe we have too many people in prison. What if we conducted a one-time release of prisoners?Okay, let's go!
Changing the sentence length will change the number of prisoners incarcerated at a each point in time. First, let's change the sentence length for burglaries.1
Now let's change the sentence length for assaults. Notice how changing the sentence length yields different effects for different types of crimes. This is because different types of crimes have difference costs of crime.
Your sentence length increase/decrease for burglaries created a benefit worth at a cost of . This means that your policy has a net benefit of , which comes out to a net benefit of per prisoner.
Your sentence length increase/decrease for assaults created a benefit worth at a cost of . This means that your policy has a net benefit of , which comes out to a net benefit of per prisoner.
Decreasing penalties for minor crimes will result in a lower prison population. What percentage of crimes would you like to reclassify?
Your crime reclassification created a benefit worth at a cost of . This means that your policy has a net benefit of , which comes out to a net benefit of per prisoner.
We can directly lower the number of incarcerated offenders by conducting a one-time release of prisoners. As long as it’s not repeated, this has the advantage of not decreasing general deterrence of crime. How many prisoners would you like to release?
 The calculations for changing sentence lengths are only valid for relatively small changes.
 The average sentence reduction from a prisoner release is assumed to be about 60 days. Therefore even though the annualized benefit is large, the net benefit is not so large.