Shadow of the Wave is going around in circles here.
He made a claim that killing someone caused you to lose your own right to life.
Then he went on to explain that by saying society had to prevent the killer from killing again, and upon hearing that life imprisonment would accomplish the same goal, he simply said he felt it was not adequate punishment.
None of that has to do with the original statement and my question.
We do not need to waste space filling up our prisons with people that serve no purpose in society other than destroying it. My explanation was basic reasoning for the death penalty. Yes, life imprisonement can work as well, but my personal philosophy remains that people should be killed for killing.
In response to benwah's comment, I really didn't think I needed to get into intent, but sometimes people just assume things in order to fit their own argument. Killing someone who kills another is once again helping society. The person killing that person would be saving others rather than becoming part of the problem.