For starters, and for what it’s worth, I also — like Alexham and Michael Joseph — oppose capital punishment. (That said, and like Alexham and Justice Scalia, I believe that the Constitution permits, though it constrains the application of, the death penalty.) And, as it happens, I was at the excellent, provocative conference (and presented this paper) at which Justice Scalia presented his essay, to which Alexham linked, indicating his disagreement with what he takes to be the position set out in the Catechism and in Evangelium vitae.
It remains, it seems to me, a tricky and unresolved question: If it is the case that the death penalty is almost always immoral — that is, as Section 2267 puts it, if it is true that the cases in which it is “the only possible way of effectively defending human lives against the unjust aggressor” are “‘very rare, if not practically non-existent'” — then why, exactly, is it the case? It is, after all, not the Church’s teaching that “punishment”, properly understood, is justified consequentially, i.e., in terms of its ability to deter and incapacitate. (It is not the case that only those punishments are justified that deter or incapacitate.) Justice Scalia is right — isn’t he? — to point out that the Church long taught, or at least did not dispute, that capital punishment can constitute morally justified retribution. The reasoning in Section 2267 seems to assimilate the imposition of capital punishment to private self-defense — both may be permissible when and to the extent necessary to defend against unjust aggression. But, I would have thought that, in the Tradition, “punishment” has not been so assimilated. What is it, then, that makes the death penalty an unjust punishment — and, to be clear, I’m happy to assume that it is — as opposed to a disproportionate defensive move?
Put another way — is there “another shoe” that needs to drop, on this matter, after Evangelium vitae?