Capital punishment is a one way street, and we have a history of realizing -- sometimes years later -- that we convicted someone based upon flawed or fraudulent

Capital punishment is a one way street, and we have a history of realizing -- sometimes years later -- that we convicted someone based upon flawed or fraudulent evidence. You can't really go back and say "sorry, my bad" to a corpse. Er, I guess you can, but it doesn't achieve much. You can't undo 20 years of incarceration either, but you can let someone out and give them some money to get restarted. This happens even in capital cases. http://madamenoire.com/73840/exonerated-after-execution-12-men-and-one-woman-found-innocent-after-being-put-to-death/ http://madamenoire.com/73840/exonerated-after-execution-12-m... From self-interest alone, we should all favor judicial penalties that can be undone if the system makes a mistake. We frequently make mistakes with, e.g., lineups, fingerprints, miscalculating the uniqueness of certain dna evidence, etc. So it's useful to structure the system to be robust to those errors.