A very interesting concurring opinion yesterday, in United States v. Craig (7th Cir. Dec. 18, 2012); here’s a slightly trimmed version:

[From the panel opinion, which Judge Posner joined.] The defendant pleaded guilty to four counts of producing child pornography. He produced them by photographing his repeated sexual assaults on a girl who was a friend of his daughters and sometimes slept over at his house. He obtained additional pornographic images of her by threatening to kill her unless she photographed herself in sexually explicit poses and emailed him the images. The abuses began when she was 11 years old and continued until she was 14….

[T]he statutory maximum sentence for each count of conviction was 30 years. (It would have been longer had the defendant had previous convictions, but he didn’t.) The judge sentenced him to the 30–year maximum on one count and to concurrent sentences of 20 years on each of the remaining three counts, but he ordered that the set of 20–year sentences be served consecutively to the 30–year sentence, making the total sentence 50 years. The judge was entitled to do this….

[Judge Posner’s concurrence:] I write separately merely to remind the district judges of this circuit of the importance of careful consideration of the wisdom of imposing de facto life sentences. If the defendant in this case does not die in the next 50 years he will be 96 years old when released (though “only” 89 or 90 if he receives the maximum good-time credits that he would earn if his behavior in prison proves to be exemplary)…. [I]n all likelihood the defendant will be dead before his prison term expires.

Federal imprisonment is expensive to the government; the average expense of maintaining a federal prisoner for a year is between $25,000 and $30,000, and the expense rises steeply with the prisoner’s age because the medical component of a prisoner’s expense will rise with his age, especially if he is still alive in his 70s (not to mention his 80s or 90s). It has been estimated that an elderly prisoner costs the prison system between $60,000 and $70,000 a year.

That is not a net social cost, because if free these elderly prisoners would in all likelihood receive Medicare and maybe Medicaid benefits to cover their medical expenses. But if freed before they became elderly, and employed, they would have contributed to the Medicare and Medicaid programs through payroll taxes — which is a reminder of an additional social cost of imprisonment: the loss of whatever income the prisoner might lawfully have earned had he been free, income reflecting his contribution to society through lawful employment.

The social costs of imprisonment should in principle be compared with the benefits of imprisonment to the society, consisting mainly of deterrence and incapacitation. A sentencing judge should therefore consider the incremental deterrent and incapacitative effects of a very long sentence compared to a somewhat shorter one. An impressive body of economic research … finds for example that forgoing imprisonment as punishment of criminals whose crimes inflict little harm may save more in costs of imprisonment than the cost in increased crime that it creates. Ours is not a “little crime” case, and not even the defendant suggests that probation would be an appropriate punishment. But it is a lifetime imprisonment case, and the implications for cost, incapacitation, and deterrence create grounds for questioning that length of sentence.

For suppose the defendant had been sentenced not to 50 years in prison but to 30 years. He would then be 76 years old when released (slightly younger if he had earned the maximum good-time credits). How likely would he be to commit further crimes at that age? … [A]lthough persons 65 and older are 13 percent of the population, they accounted for only seven-tenths of one percent of arrests in 2010. Last year 1,451 men ages 65 and older were arrested for sex offenses (excluding forcible rape and prostitution), which was less than 3 percent of the total number arrests of male sex offenders that year. Only 1.1 percent of perpetrators of all forms of crimes against children are between 70 and 75 years old and 1.3 percent between 60 and 69. How many can there be who are older than 75?

It is true that sex offenders are more likely to recidivate than other criminals, Virginia M. Kendall and T. Markus Funk, Child Exploitation and Trafficking: Examining the Global Challenges and U.S. Responses 310 (2012), because their criminal behavior is for the most part compulsive rather than opportunistic. But capacity and desire to engage in sexual activity diminish in old age. Moreover, when released, a sexual criminal is subject to registration and notification requirements that reduce access to potential victims.

As for the benefits of a lifetime sentence in deterring other sex criminals, how likely is it that if told that if apprehended and convicted he would be sentenced to 50 years in prison the defendant would not have committed the crimes for which he’s been convicted, but if told he faced a sentence of “only” 30 years he would have gone ahead and committed them? …

Sentencing judges are not required to engage in cost-benefit analyses of optimal sentencing severity with discounting to present value. Such analyses would involve enormous guesswork because of the difficulty of assessing key variables, including one variable that I haven’t even mentioned, because I can’t imagine how it could be quantified in even the roughest way — the retributive value of criminal punishment. By that I mean the effect of punishment in assuaging the indignation that serious crime arouses and in providing a form of nonfinancial compensation to the victims.

But virtually all sentencing, within the usually broad statutory ranges — the minimum sentence that the judge could have imposed in this case, by making the sentences on all four counts run concurrently, as he could have done, would have been 15 years, and the maximum sentence, by making them all run consecutively, as he could also have done, would have been 120 years — involves guesswork. I am merely suggesting that the cost of imprisonment of very elderly prisoners, the likelihood of recidivism by them, and the modest incremental deterrent effect of substituting a superlong sentence for a merely very long sentence, should figure in the judge’s sentencing decision.