Gerry Uelman writes that the benefits of the death penalty don't outweigh its costs (Fall 2008, Santa Clara Law, pps. 10-11):
Because the death penalty is being sought, the prosecution and defense must actually prepare for two trials, one to determine guilt, the other to determine the sentence...those elements added approximately $500,000 to the cost of a homicide trial.
The bottom line: a conservative estimate of the current cost of our death penalty law in California is $137.7 million per year...to total $232.7 million [after implementing commission's recommendations].
I used to be pro-death penalty until I saw how the system works. I am still pro-death penalty in principle, but from an economic perspective, most studies show it's better to have life without parole. The other benefit of life without parole over the death penalty? Humility. The ones that were wrongfully convicted may get a chance to prove their innocence through DNA or some other new method.