Capital punishment has been in use since the origins of mankind. When humans were too stupid to figure what to do with someone who committed a crime or someone who did something that violated the laws or ethics of society then he or she was simply killed. You would think that by now we would have figured out a less rash punishment for criminals and wrong-doers but as it is with many other arcane ideas/practices (like religion) we haven't. How surprising.
The main problem with executing criminals is the fact that it just doesn't solve anything. Contrary to popular belief, killing someone who has done you wrong does nothing to alleviate the pain associated with that person's action. If someone killed your dog and let's say just for the sake of argument, that he or she was found guilty in court and sentenced to death (and you of course were all for it because you loved your dog). The guy that killed your dog is eventually executed and guess what your dog is dead but now on top of it, another human being is dead too. What have we solved? Nothing. Now lets say (again just for the sake of arguement) that the court hadn't sentenced the man to death but rather sentenced him to a few years in jail. Now lets say the man got out of jail and decided he would change his dog-killing ways and focus on discovering something extraordinary. Now lets say he does discover this extraordinary thing --lets say he proved the existence of big-foot. The fact that you decided to kill the man also means that he never made his incredible discovery. And I'm sure you really want to know whether big-foot really exists so calm down and let the man live.
Another problem with capital punishment is that its completely inhumane for someone to sit in an 8 by 12 prison cell waiting to die. I mean if your going to kill someone why not just kill them immediately instead of making them suffer the anxiety of even just knowing the date of their execution. And in any case, who are you to decide ( you being a court of law) whether someone should live or die. Seriously, if you decide to kill someone then at least give that person a chance to fight for their life. I know that sounds a bit...gladiatorial ( if thats even a word) but when you just think about it, its so stupid for someone to decide the fate of another person.
I know it may seem really unfair that if a man murders your whole family, you cant decide that you want that man to be tortured and killed because, lets face it, that is everyone's instinctual reaction. Unfortunately though people just have to accept the fact that killing someone won't make things any better or easier to deal with. For one, think of the the family of the murderer and how they, much like you, are struggling to cope not only with what their family member has done but also with the fact that he or she will be killed. Think of the pain you are causing them by deciding that you want their family member to die.