When Obama announced that his SCOTUS pick would be "empathetic," I immediately thought of Martha Nussbaum's theory that empathy (she often calls it sympathy) ought indeed to be the basis of legal reasoning, and that empathy-inspiring stories always lead our judgment in the right direction, a theory that she sets out in books like her Poetic Justice. I'm not the only one who made this connection. See here and here. (And see this for a discussion of the same issues that does not mention Nussbaum.)
The apparent connection here might be no coincidence. Both Obama and Nussbaum taught at the University of Chicago Law School (he as a non-tenure-track lecturer, she as a "distinguished service professor"), and their careers there overlapped by five years.
Obama had many opportunities to soak up Nussbaumian nostrums.
I sometimes hear it said that empathy is a source of fairness and balance in legal decisions. I believe the opposite is true.
Bear in mind what empathy is: feeling -- or more accurately, thinking you feel -- the feelings of another person based on seeing or hearing their story play out. "I feel your pain."
Now, suppose you are a judge hearing the case of a (assume for the sake of the argument) guilty criminal. Where will your empathy lead you? Well, here is the accused criminal with their affecting story to tell. Entering into the feelings of the defendant will incline you to leniency. Of course, you could also enter into the feelings of their victim. The victim will have very strong feelings about the accused. But sharing these feelings and being influenced by them would mean acting on vicarious revenge. You can't do that. Who else could you empathize with? Well, there are the future victims of crimes that you would be failing to deter if you are too lenient on the accused. But in the present decision-making situation, these other victims are mere theoretical possibilities, bloodless abstractions. You can't empathize with abstractions. So, unless you are willing to act on revenge, empathy will lead you to favor the accused criminal and to undervalue your duty to protect society against crime. Here empathy leads to bias.
Again, suppose you are on the Supreme Court, deciding a case involving the continued legality of abortion. Here there are plenty of empathy-inducing narratives about women who want or need an abortion. There are plenty of people to empathize with here. Who else? Could you empathize with the aborted fetuses? Of course not. In its early stages, when most abortions are performed, the fetus has a brain that is about as complex as that of a small fish. And it is not able to appear in your court and tell you its sad story. Empathy will bias you, then, in favor of the pro-choice position and agains the pro-life position.
Don't get me wrong: I am pro-choice myself. But this would be a very bad and unjust reason for being pro-choice.
In general, empathy will favor the person with the affecting story to tell, the one into whose feelings you (think) you can enter: the underdog, the attractive person, the person who seems nice, the person who resembles you. In the law, however, it is not the good guy who should win, but the person who has rights. Rights do not necessarily coincide with traits that make me melt with compassion.
It is best to stick with the old fashioned ideal of rational fairness. That ideal cannot be achieved perfectly, I admit. But empathy does not correct its imperfections. Like revenge, like any other sort of emotion-based decision-making, empathy systematically biases you in favor of one party at the expense of the other.
(I have criticized Nussbaum's sympathy theory at greater length here; a short version under a different title can be found here. I have attacked her on a variety of other, related issues here. If you are able to access it, you can find John Kekes' blistering review of her book Hiding from Humanity here.)