During a period when “mass incarceration” (see my article about it at https://davidhlukenbill.wordpress.com/2015/10/06/mass-incarceration/ ) and large scale prison releases are the dangerous trends—at least, so far, in California and in the federal prison system—a reminder that prisons do work is timely, even from this article published in 1996, and virtually nothing the author describes from then is much different now, except the finances.

An excerpt. 

All 30 Republican governors elected or re-elected in 1994 promised to get tough on crime. Most, like George Pataki of New York, are keeping their word. But several, like Tommy Thompson of Wisconsin, who has said he would build no more prisons, are quietly promoting plans to put more convicted criminals back on the streets. 

Most experts applaud Governor Thompson’s new-found “wisdom” and lament Governor Pataki’s “hard-line” approach. As these experts love to repeat, “incarceration is not the answer.”

If incarceration is not the answer, what, precisely, is the question? If the question is how to prevent at-risk youths from becoming stone-cold predators in the first place, then, of course incarceration is no solution.

But if the question is how to restrain known convicted criminals from murdering, raping, robbing, assaulting and stealing, then incarceration is a solution, and a highly cost-effective one.

On average, it costs about $25,000 a year to keep a convicted criminal in prison. For that money, society gets four benefits: Imprisonment punishes offenders and expresses society’s moral disapproval. It teaches felons and would-be felons a lesson: Do crime, do time. Prisoners get drug treatment and education. And, as the columnist Ben Wattenberg has noted, “A thug in prison can’t shoot your sister.”

All four benefits count. Increased incarceration explains part of the drop in crime in New York and other cities. As some recent studies show, prisons pay big dividends even if all they deliver is relief from the murder and mayhem that incarcerated felons would be committing if free.

In two Brookings Institution studies, in 1991 and 1995, the Harvard economist Anne Piehl and I found that prisoners in New Jersey and Wisconsin committed an average of 12 crimes a year when free, excluding all drug crimes. In other studies, the economist Steven D. Levitt of the National Bureau of Economic Research estimated that “incarcerating one additional prisoner reduces the number of crimes by approximately 13 per year.”

The economists Thomas Marvell and Carlisle Moody of William and Mary College found that “a better estimate may be 21 crimes averted per additional prisoner.” Patrick A. Langan, senior statistician at the Justice Department’s Bureau of Justice Statistics, calculated that tripling the prison population from 1975 to 1989 may have reduced “violent crime by 10 to 15 percent below what it would have been,” thereby preventing a “conservatively estimated 390,000 murders, rapes, robberies and aggravated assaults in 1989 alone.”

Studies by the Bureau of Justice Statistics found that 94 percent of state prisoners in 1991 had committed a violent crime or been incarcerated or on probation before. Of these prisoners, 45 percent had committed their latest crimes while free on probation or parole. When “supervised” on the streets, they inflicted at least 218,000 violent crimes, including 13,200 murders and 11,600 rapes (more than half of the rapes against children).

Retrieved October 8, 2015 from http://www.brookings.edu/research/opinions/1996/01/16crime-john-j-diiulio-jr