Something the Iranian Government and I Agree on: I particularly like the involvement of the victims' relatives in the killing of the monster; I think that if he'd killed one of my relatives, I would have wanted to play a role in killing him. Also, though for many instances I would prefer less painful forms of execution, I am especially pleased that the killing — and, yes, I am happy to call it a killing, a perfectly proper term for a perfectly proper act — was a slow throttling, and was preceded by a flogging. ...Well, you get the idea. There's much, much more where that came from.
I should mention that such a punishment would probably violate the Cruel and Unusual Punishment Clause. I'm not an expert on the history of the clause, but my point is that the punishment is proper because it's cruel (i.e., because it involves the deliberate infliction of pain as part of the punishment), so it may well be unconstitutional. I would therefore endorse amending the Cruel and Unusual Punishment Clause to expressly exclude punishment for some sorts of mass murders.
Naturally, I don't expect this to happen any time soon; my point is about what should be the rule, not about what is the rule, or even what is the constitutionally permissible rule. I think the Bill of Rights is generally a great idea, but I don't think it's holy writ handed down from on high. Certain amendments to it may well be proper, though again I freely acknowledge that they'd be highly unlikely.
In any event, there's nothing unconstitutional about letting victims' relatives participate in the execution; it's only the use of cruel means that would require an amendment. ...
Why would my humanity be diminished by participating in the killing of a monster (he had sexually abused and then murdered at least about 20 children), or even by deliberately inflicting pain on him? It seems to me that this is the reaction to a natural, understandable, and laudable human impulse to avenge (even if in a ridiculously inadequate way) the abuse and death of so many innocents. Why shouldn't one say that our humanity is diminished if this monster is allowed to live on, or even to die a painless death, when his victims and their families endured unimaginable pain?
You know, I'm not yet sure that I'm 100 percent against the death penalty in every situation, though I may be headed that way. Certainly, vicious acts of violence may have worked at some level to keep people in line over the course of our evolution as a species. However, it seems pretty obvious to me that evolving away from that method of justice could only mean less violence at large in our society in the future. Don't advocates of such savagery understand the truth of aphorisms like "Those who live by the sword, die by the sword? Don't they understand the idea of modeling human behavior? Don't they understand that when we execute someone in a cruel and violent way, it inevitably sends a message that such violence is acceptable elsewhere, whether we intend to send such a message or not?
Update: Another conservative blogger and college professor, Glenn Reynolds apparently agrees with Volokh.