By “there” you presumably mean in the Old Testament, not Genesis 9:6 in particular, which simply says that murderers are to be put to death. We can read this a little more broadly (as the Church, historically, always has) as laying down a general principle: that human life is sacred precisely because of its conformity to the rational nature of God, and that the illicit taking of human life is a crime of the highest magnitude which merits the highest punishment. Subsequent passages in the OT (i.e., in Deuteronomy and Leviticus and elsewhere) don’t presume to lay out moral principles, they just extrapolate the general principle to particular cases. Obviously, general moral principles cannot change, even if the circumstances of their application can; so the fact that both of them appear in the OT is not in itself evidence that we have to either accept both or reject both.
Wouldn’t the release of innocent people from death row be evidence that the system and its safeguards are working? (Nice username by the way, I loved FF8!)
This doesn’t make much sense. “Morality” has two sources: the natural and the divine laws. Both of these are essentially unchangeable, the former being rooted in changeless human nature and the latter in changeless divine nature. If the death penalty was morally permissible yesterday, it is morally permissible today.
Of course that doesn’t mean the death penalty is necessarily good, because moral permissibility is a necessary but insufficient condition for deciding whether or not a particular course of action ought to be undertaken. By way of example, it is morally permissible for a man to make love to his wife, even if it were a terrible idea for prudential reasons (i.e., she is currently gravely ill and pregnancy could kill her). I read the Church as saying that the death penalty should be avoided for prudential reasons, i.e., because modern society no longer has a clear conception of the state as a dispenser of divine justice (or even a clear conception of “justice”), so that execution of criminals tends to conduce, not to an appreciation of divine justice, but to a valorization of the wrath of the mob and the supreme power of the totalitarian state. And I happen to agree with that assessment and with the conclusion that comes from it. But that is certainly different from saying “the death penalty is immoral today,” which, beyond being a non sequitur, is at odds with what the Church teaches.
It might. But it might also be an occasion for conversion – since the prospect of impending death tends to liberate people from worldly attachments that might be an impediment to conversion. Personally, I would be very happy to know the exact hour of my death, and to have access to the Sacraments immediately beforehand.