> ...I do not think pre-meditated murder by uneffected agents acting on behalf of the state is proportionate.
I'm 100% with you. The way it's done in our society is unjust. But what I'm trying to get at is, if putting people to death is fundamentally unjust. Most people I've talked to that are opposed to it tie the two inseparably and it clouds the morality of the fundamental question.
As far as your other points, I disagree entirely. Any credible threat of violence can be met with whatever preventative measures the potential victims warrant appropriate. I don't have to wait til I'm about to be killed to protect myself, if I know an attempt on my life is impending I can justifiably act.