Joseph M. Bessette in the Wall Street Journal:
Consider this example that the philosopher Edward Feser and I recount in our book, By Man Shall His Blood Be Shed: A Catholic Defense of Capital Punishment: At a professional conference, a criminologist reported that two burglars had broken into his mother’s apartment and tied her up as they searched for valuables. As they were about to leave, one said: “She has seen us and can identify us. Should we kill her?” “No,” answered the other, “we don’t want to risk the death penalty.” They let her live. One can hardly imagine a clearer example of deterrence.
Another example comes from Sen. Dianne Feinstein of California. In the 1960s she served on the California Women’s Parole Board. At one hearing, Mrs. Feinstein asked an armed robber seeking release from prison why she never used a loaded gun. “So I would not panic, kill somebody, and get the death penalty,” she answered. That convinced Mrs. Feinstein that (in her words) “the death penalty in place in California in the ’60s was in fact a deterrent.”
A third example is recounted by law professor Robert Blecker, who had spent years interviewing prisoners. A veteran criminal told Mr. Blecker that the reason he spared the life of a drug dealer in Virginia whom he had tied up and robbed was because the state had the electric chair. In a similar situation in the District of Columbia, which had abolished the death penalty, the criminal had killed his victim. “I just couldn’t tolerate what they had waiting for me in Virginia,” he said.
These examples are powerful illustrations that the death penalty can and does deter some would-be murderers. Like the rest of us, criminals want to live, and, as the these examples show, they will often adjust their behavior accordingly. Without the death penalty, what incentive would a “lifer” have not to kill while in prison or, if he escaped, while on the run?
There is also a deeper kind of deterrence, largely overlooked in discussions of the death penalty, which doesn’t require rational calculation. When society imposes the ultimate punishment for the most heinous murders, it powerfully teaches that murder is a great wrong. Children growing up in such a society internalize this message, with the result that most people wouldn’t even consider killing another human being.
I would add that eliminating the death penalty undermines the message that murder is a great wrong and contributes to leniency and a ratcheting down of penalties in respect of non-capital crimes such as rape.
Here the principle of justice, which demands that malefactors receive a punishment proportionate to their offense, and deterrence of this deeper sort meet. If we abolish the death penalty for even the most heinous and coldblooded murderers, we fatally undermine the idea of justice as the cornerstone of our criminal-justice system. Over time justice will be replaced by a therapeutic or technocratic model that treats human beings as cases to be managed and socially engineered rather than as morally responsible persons.