Plus, regarding deterrence, the murder rate is lower in states that don't have the death penalty.
imo capital punishment is unethical.
fyi: countries that have the death penalty in red
1. From the document linked (http://www.deathpenaltyinfo.org/documents/FactSheet.pdf), i see that 46 people were executed in 2010 in the US. I don't think that 46 more prisoners would make a lot of difference on prison overpopulation. Besides, most of the prisons population is made of people with drug related offences. Here (in italy) we have the same problem with prison over-population, and the most sensible proposal that has been made is to release from prison (and find an alternative "punishment") for every non-violent crime. That would cut the prisons population by an astonishing 40% (really? we keep in prison, sometimes for years, people who have stolen a bag of money without harming anyone? O_o)
2. As many have already pointed out, a prisoner sentenced with a capital punishment costs more than a non-capital one. And anyway, i find quite difficult, on a moral basis, to justify a death penalty with money savings...
3. I suggest you to read this 18th century essay: On Crimes and Punishments. (chapter 28, in particular)
It explains very well why a capital punishment doesn't work as a deterrent. What really works is certainty of punishment and immediate punishment.
But in any case, even if death sentences were effective, i find them reprehensible on moral grounds. If the principle is that you cannot take a man's life, how can you justify the state doing the same thing?
IMO, the death penalty should be much more common. It should be applied when:
A) The crime in question is considerably gruesome or violent.
B) There is enough evidence that there is no doubt that they are guilty.
I don't know who would decide the parameters for this.
While I agree that murderers and rapists do not have a right to live, the problem with having the death penalty on the table is that it means you have to trust juries and the rest of the legal system to never make a mistake.
As the countless cases of people wrongly convicted of such heinous crimes proves, we absolutely cannot trust that such mistakes will not be made. In too many cases a clever psychopath can pin his crimes on an innocent third party, sometimes a loved one of the victim(s), thereby getting more deaths for the effort of the original killing(s). The only way to ensure that such miscarriages of justice can eventually be corrected is to take the death penalty option permanently off the table. Anyone who is convicted and whose conviction is not reversed by fresh evidence and a new trial should be locked up until they die either at the hands of fellow prisoners, or of old age. I disagree with giving such felons a 2nd chance.
The cost of imprisoning someone for life is less than the cost of the endless appeals that occur in death penalty cases. Also, juries require a higher level of conviction to convict in a death penalty case, so it is easier for a clever lawyer to get a guilty murderer off without any penalty if a conviction would carry a death penalty.
The death penalty is not a deterrent. Certainly in the case of religious psychopaths, who believe in the 18 virgins reward, it is something they actively seek. There are also cases of divorcees who are suicidal and angry at the dissolution of a relationship. Often these end in murder suicides. Again, a death penalty is no deterrent. Even in the case of property criminals such as bank robbers who kill in the "line of duty", the thought that they might get caught and executed doesn't come up at the time.
So, no matter how you slice it, the only benefit of the death penalty is to assuage our sense of outrage and the desire for revenge for a heinous act. The downsides of the death penalty far outweigh these considerations.
It is interesting that the most ardent supporters of the death penalty are those who distrust government agencies to do the right thing. These people support privately owned prisons to hold all the people that are arrested for victimless crimes such as possession of a few grams of marijuana. Yet these people trust their lives to the legal system which has time and again proven that it can't be trusted with the death penalty. Before you consider lobbying for the death of some apparently clearly guilty psychopath who has done something incredibly repulsive and clearly deserving of the death penalty, consider that this person might be you who has been framed for that act. There is no way for you to know how often this really happens, and there is nothing you can do to prevent it happening to you.
IMHO, it is important to not let our inevitable emotional reaction to a heinous crime blind us to the above implications of having a death penalty option.
That being said, I really like the "Dexter" TV series and novels with their idea that there is a class of psychopath whose prey of choice is other psychopaths. :)
1. It's ineffective. The death penalty does nothing to deter crime.
2. It's inhumane. The death penalty is the definition of "cruel and unusual punishment".
3. It can be, and often is, applied unjustly. More non-whites than whites are given death sentences for identical crimes.
4. It's possible for innocent people to be convicted of crimes, and even given death sentences.