Well, I think imprisonment is cruel and unjust, but aside that, you and I have already agreed that killing someone in self defense is just, and you haven't actually responded to my reasoning at all. You're reiterating your position, which is fine but doesn't lend itself well to fruitful discussion.

A jury, the state, all that I can agree with. That doesn't mean though that a group putting someone to death is always unjust, just that our mechanisms for doing it are.

I'd argue that me and my buddy deciding to go grab someone and kill them for, say for example, killing my cousin or raping my nephew or threatening to do so is entirely just. 

 Which part haven't I responded to? I'll do my best. 

 Well, youre saying "bottom line murder is wrong", I'm saying it's not always murder, we seem to be in agreement on that. You're saying when the state does it they commit injustice because of the process by which they do it, I'm in agreement with you. But you keep making those same points which aren't in contention at all and which we have already addressed. 

 I think I used up all my brain cells this morning. Anyways... I can respect that you read everything and still disagree.  

 A jury is explicitly not the state. 

We haven’t had real juries for a long time. 

My entire argument about death sentence rests on first restoring the true jury trial. 

https://mises.org/library/book/lets-abolish-government