Don Boudreaux explains that harsh penalties may cause more crime:
Have you heard the one about how economists who study law explain why rape isn't punished as severely as murder?
...When I ask my fellow partygoers this question, they typically have no good answers. After watching them struggle to figure out where I'm going with this question, I hit 'em again: "Knowing that we can reduce the number of rapes by making it a capital crime, does the fact that we don't punish rape this severely mean that our society doesn't care as much as it should about women? Does it mean that we secretly think that there's some value to rape?"
...Put yourself in the place of a man who is a threat to rape women. If you learn that rapists will no longer merely be locked in prison for years but, instead, executed, you're a bit less likely than before to rape. That's good. But suppose that this higher "marginal" cost of committing a rape isn't sufficient to prevent you from raping a woman. So you rape a woman. Once you commit the rape, you are subject to being executed if you're caught and convicted.
What will you now lose by becoming also a murderer? Nothing. In fact, you have everything to gain by killing your rape victim. If you let her live, you run a real risk of being identified, captured and convicted -- and then executed. But if you murder the woman after you rape her, you reduce your chances of being caught and convicted. (The chief eyewitness to your heinous crime, after all, will be in her grave.) So with nothing to lose and much to gain by killing your rape victim, you're more likely to kill her than you would be if the penalty for rape were lower than is the penalty for murder.
Punishing rape less severely than murder ensures that rapists still have something more to lose if they kill their victims.
Sadly, life and theory are correlated:
In August 2000, Nicholas Markowitz, 15, was kidnapped in a Los Angeles suburb, held for several days, and then murdered by a group of men who had grown up with Markowitz' older brother. The larger motives for this crime remain murky, with allegations of prior drug dealing, drug debts, and attempted insurance fraud on the part of the older men still unresolved. It is clear that the young victim was innocent. What is clear as well is that the de facto absence of a death penalty in California led to the decision to murder the teenager.
After one of alleged killers, Jesse James Hollywood -- no, I am not making that up -- "called his lawyer and learned the severe penalty for kidnapping, police say, the young men decided they had to kill Nicholas" (Los Angeles Times, August 26, 2001). In other words, since the penalty for kidnapping effectively was a life sentence or something close to it, and since the perceived probability that the kidnappers would be apprehended and convicted was high, the marginal (or "extra") penalty for murdering Markowitz was perceived to be low or zero, in that the likelihood of actual subjection to capital punishment in California is trivial -- California has executed ten individuals since 1976. And it's a punishment that, in any event, is delayed one or two decades by the appeals process. Accordingly, the prospective act of murder, even upon arrest and conviction, would yield the same life sentence already looming. So why not get rid of the central witness to the kidnapping?
HT to DOL for the kidnapping story.