In this WSJ op-ed, Duke visiting professor John Hasnas uses Bastiat's principle to show what is wrong with judging based on empathy with the party before the court rather than the rule of law.
The law consists of abstract rules because we know that, as human beings, judges are unable to foresee all of the long-term consequences of their decisions and may be unduly influenced by the immediate, visible effects of these decisions. The rules of law are designed in part to strike the proper balance between the interests of those who are seen and those who are not seen. The purpose of the rules is to enable judges to resist the emotionally engaging temptation to relieve the plight of those they can see and empathize with, even when doing so would be unfair to those they cannot see.
Calling on judges to be compassionate or empathetic is in effect to ask them to undo this balance and favor the seen over the unseen. Paraphrasing Bastiat, if the difference between the bad judge and the good judge is that the bad judge focuses on the visible effects of his or her decisions while the good judge takes into account both the effects that can be seen and those that are unseen, then the compassionate, empathetic judge is very likely to be a bad judge. For this reason, let us hope that Judge Sotomayor proves to be a disappointment to her sponsor.
Hasnas's examples are all from civil law, but the principle applies to criminal law as well. We constantly hear calls for mercy for the defendant before the court. Mercy has a place and sometimes is the right decision, but we should never forget the danger of excessive mercy to persons not before the court, persons with a claim to society's protection that is at least equal to and usually greater than the defendant's. The criminal law saves the lives, health, and property of law-abiding people through incapacitation and deterrence, and failure to enforce it has real impact on real people, even though they may be unseen and unknown at the time of sentencing.
Here is an exercise for those who oppose the death penalty, the issue on which this comes in to sharpest focus. Deterrence has not been conclusively proved, but no reasonable person familiar with the evidence can say it is not a substantial possibility that an enforced death penalty will save lives. Picture the one person in the world closest to your heart. If you knew to a certainty that that person would be murdered as a result of abolition, would you still favor it? If not, is there any moral basis for a different view when the additional persons to be murdered are unseen and unknown yet very real people?