Aaaaaaand now we have the rest of the story. Never mind due process. Never mind the 8th Amendment, if someone commits a crime, let's just kill'em.
First of all, it's already a given that if a criminal puts someone in extreme danger and the defender must use deadly force in self-defense that the criminal is not, at that precise moment going to be entitled to due process, etc. Because of the extreme nature of his crime and the fact that the citizen defender can't rely on the government for help at that moment, the citizen is entitled to defend himself even if it costs the attacker his life.
Second, your comment reveals a fundamental disconnect between the purpose of deadly force and your vision of what it is for.
Deadly force is NOT about the government punishing a criminal by giving a citizen the right to shoot him. Legal punishment for a crime committed comes ONLY as the result of a trial.
Punishment is determined by a set of laws completely and entirely distinct from the deadly force laws and is administered ONLY by the government.
It is completely incorrect to equate the outcome of a justifiable self-defense encounter with punishment administered by the government. The two things are entirely and completely separate and attempting to conflate the two reveals a significant misunderstanding of both concepts.
By the way, this is a common misconception on BOTH sides of this argument. On the one side you have people advocating that criminals should be shot by law-abiding citizens as an alternative to incarceration or other punishment and on the other side you have people arguing that justifiable deadly force isn't fair because it imposes a penalty more severe than the common legal penalty associated with the crime in question. Both views are incorrect because self-defense laws are NOT about punishing criminals. They are about defending innocent life under extreme circumstances.
And THAT'S why SYG is so dangerous to our society.
That's got nothing to do with SYG. Even under SYG it's illegal to just shoot someone for merely threatening you with deadly force. There are a number of legal considerations that must be satisfied before deadly force is justifiable and that is true even when retreat is not one of those legal considerations.
I get that you don't agree with SYG, but it's hard to take you seriously when it's obvious that you haven't taken the time to learn what it means. Your comments reveal a significant lack of understanding of what SYG is and what it means. That obvious misunderstanding effectively discredits you to anyone who has taken the time to develop a basic understanding of SYG.
And, I should point out that given that the SYG concepts have been explained to you quite thoroughly and you have had ample time to verify the accuracy of the explanations, at some point, if you continue mischaracterize SYG it will be impossible to pretend that it's merely the result of ignorance.