I don't buy the argument that the death penalty is impractical because you can't undo it if someone is later found to be innocent. You can't give someone back 27 years of their life either. With or without the death penalty, a very, very small minority will suffer injustice and be falsely charged. However, this cannot stand as a barrier to having any sort of effective justice system on the larger scale.

People say you have to be as close as possible to 100% certain of a person's guilt before administering the death penalty, but then I would think the same applies to sentencing a person to prison. What do judges say? "Oh well, he's only going inside for a couple of years so it doesn't matter". Hmm don't think so.