Irrelevant truth. So what? If you even had the slightest inkling of a perfect system, share your enlightenment with the rest of us.
And in this case, the innocent person was put to death. That is a crime.
Complete and utter BS. The chance this clown was innocent is so small that claiming his innocence can only amount to massive intellectual dishonesty. It doesn't take twenty years to execute someone without reason. By the time the switch is pulled, the case has been checked and rechecked dozens of times.
Are innocent people occasionally sentenced to death? Of course. Are innocent people executed? In spite of the ardent fantasies of anti-death penalty activists, apparently not. If an innocent person were executed, anti-death penalty whackjobs wouldn't have to resort to a whole pile of half-truths and deceptions to insinuate that this or that guy may, possibly have been innocent if you essentially ignore all the facts of the case.
The perfect system is one that leaves open the possibility that society will be able to correct its mistake. That really is not a perfect system. But it is a whole lot better than the one we have now.
Oh yes, I see your point - if it cannot be made perfect then why bother making it better?