Gun violence is a major social problem in Chicago and other American cities. The Illinois legislature is considering a proposed law that would increase the mandatory minimum prison sentence for having an illegal gun to three years and would require people serve at least 85 percent of their sentence.
Some people are understandably concerned that this bill will increase the human and financial costs of incarceration. But this bill is likely to pay for itself five times over by preventing violent crime.
The best estimate of the bill's potential costs comes from the Illinois Sentencing Policy Advisory Council. SPAC finds that the law would increase the number of people in Illinois prisons by more than 6,000, at a cost to the state of $131 million a year.
That cost estimate is almost surely too high. A growing body of research suggests that increased certainty of punishment deters crime, including gun crime. The deterrent effect reduces the number of crimes and the number of people sent to prison. Punishment need not be draconian, it just needs to be applied consistently.
If a new mandatory sentencing law in Illinois creates more consistency of punishment for illegal gun possession (as a similar law seems to have done in New York City), fewer people will be sent to prison than SPAC suggests.
The costs of the proposed law are just part of the picture, though. What about the benefits?
The University of Chicago Crime Lab, which I direct, analyzed data on people placed on probation for illegally carrying a gun in Cook County. These are the people who would wind up in prison under the proposed law. Our research finds that at least 3,800 crimes, including more than 400 serious violent crimes, would be prevented each year in Illinois because the people who would commit those crimes would be in prison. The deterrent effects of the law — the certainty of prison time — would increase the number of crimes averted.
We estimate the social cost of these crimes at more than $700 million — more than five times as much as the SPAC estimate of the cost of incarceration. Social cost includes such tangibles as the value of stolen property and such intangibles as the fear and pain suffered by victims of crime.
These social costs fall disproportionately on the most disadvantaged residents of Illinois, including people who live in distressed South Side and West Side neighborhoods of Chicago. That's because they are more likely to be victims of crime.
Lawmakers can debate whether there are other ways to get more consistent punishment for illegally carrying a gun. But we can't focus on the costs of preventing crime without considering the real costs when crimes are committed. A narrow focus on costs would undermine almost everything government agencies and nonprofit groups do, including many promising social programs carried out statewide that also help reduce crime. This sort of narrow focus would hurt, not help, efforts to reach the goal we all share — to reduce the toll of gun violence in Chicago and the rest of Illinois.
Jens Ludwig is a University of Chicago professor and director of the university's Crime Lab. He was elected in 2012 to the Institute of Medicine of the National Academy of Sciences.
Copyright © 2015, Chicago Tribune