The ceremony of law smells of both blood and paper, for it is when the impulse of violence becomes subject to rule, when combat becomes contest. I know nothing about the specific case we are all thinking about. I simply want to propose a thesis.
The question is, under what circumstances within a civilized society is violence (threat of or infliction of physical pain, injury or death) permissible? To say none is to value the life of an assailant over that of a victim, and I can think of no argument for that. Rules have purposes, and life, all life, has value. So my suggestion is that violence is justified only to protect innocent life from imminent violence, and the justification for that is the value of innocent life, and necessity. Because life itself has value, there is an obligation to minimize harm to the assailant the degree compatible with ensuring safety for the prospective victim. Here centuries of common law agrees with me, as long as we are out in the world. It is when we enter the prison that everything changes.
But why does it? I can see no justification for inflicting physical pain, injury or death on the defenseless and the disarmed. A person in custody is defenseless and disarmed. Therefore there is no justification for executing a prisoner.
This view is not a “Christian” view. No one is being asked to turn the other cheek, and none of this precludes vigorous self-defense when an assailant is at liberty, police firefights in pursuits, what have you. War is hell. The intuition behind this is not one which finds self-assertion itself repugnant. Rather, it is an intuition about what constitutes a “fair fight.”
In our culture, we make films that gratify the desire to see violence unleashed against the absolutely helpless. The genre is called “torture porn.” When the State does it to gratify the same impulse, it is live theater torture porn. Turning the condemned into a gladiator would be more moral. Give up the complete control, or give up the violence, for you cannot have both, without arousing the revulsion of all civilized people.