I'd have to say Easytiger pretty well summed it up. (And with Tolkien no less. Bonus points!
) In theory, this practice works. But until we can be sure we have the right people, it won't be practical. (and it's the appeals process that is costing so much money, not the executions)
As for Quadraton's point, it's NOT the same thing. Murder is the taking of life without justification. If I shoot a person in self defense, it isn't a crime. If I shoot a person because I just don't like them, that is a crime.
Think of the death penalty as the revolver some people keep in their bed-side drawer. If used properly, it keeps you and your loved ones safe from harm. If used improperly, you end up shooting your dog in the middle of the night on accident.