The justice system is administered by humans. There is no other choice. Humans can make mistakes sometimes intentionally. I unlike you have faith in the justice system and certainly zero is hyperbole.
In the last 20 years with DNA, groups who do independent investigations of capital punishment case, liberal courts, and other technological improvements, executing an innocent person is very unlikely and becoming more so.
The question is what is the benefit to the death penalty if it is moral and we do our best job we will have some one innocent executed now and then.
What should be the penalty for someone doing life after a murder conviction who kills a guard or other inmate. Then can we execute them? Why can a police officer shoot a person who draws a weapon beefier they fire it. Shouldn’t they wait until there is a shot to make sure the person is intending to kill them? We give that power to the police because not is moral for the officer to live and the person drawing a weapon to die no matter what they are thinking or intending.
Do we not attack city in war knowing innocent civilians will die. Why because the benefit outweighs the negative. Life is too important to let people kill others and then maintain their own freedom of life.
beefier=before
The rest of your post has some interesting points. A few corrections or responses are in order:
What should be the penalty for someone doing life after a murder conviction who kills a guard or other inmate.
Prisoners should be confined to individual cells, and should generally live a miserable existence. Threats to guards and fellow inmates are mainly a function of the way we coddle them rather than punishing them.
Why can a police officer shoot a person who draws a weapon beefier they fire it. Shouldn’t they wait until there is a shot to make sure the person is intending to kill them? We give that power to the police because not is moral for the officer to live and the person drawing a weapon to die no matter what they are thinking or intending.
Two points here ...
1. You have erased the very wide, obvious line between an imminent threat and a deliberative process where there is no imminent threat. If a convicted criminal represents an imminent threat, then why not shoot him right in the courtroom rather than wait until he tries to escape and grabs a gun from the court officer?
2. Why even mention the police at all? We don't "give" the police the power you describe. The right of self-defense applies to individuals regardless of whether or not they are police officers.