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&#x27;t really go back and say &quot;sorry, my bad&quot; to a corpse. Er, I guess you can, but it doesn&#x27;t achieve much.  You can&#x27;t undo 20 years of incarceration either, but you can let someone out and give them some money to get restarted.<p>This happens even in capital cases. <a href="http:&#x2F;&#x2F;madamenoire.com&#x2F;73840&#x2F;exonerated-after-execution-12-men-and-one-woman-found-innocent-after-being-put-to-death&#x2F;" rel="nofollow">http:&#x2F;&#x2F;madamenoire.com&#x2F;73840&#x2F;exonerated-after-execution-12-m...</a><p>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&#x27;s useful to structure the system to be robust to those errors.