Pope Francis caused no little controversy by revising §2267 of the Catechism of the Catholic Church to assert that “the death penalty is inadmissible because it is an attack on the inviolability and dignity of the person.” The problem, of course, is that previous Catholic teaching, including the previous version of §2267, had not ruled out the moral permissibility of capital punishment in certain contexts.
The brewing controversy was and continues to be whether Pope Francis is here faithfully and organically developing doctrine or whether he has simply contradicted centuries of Catholic teaching. Responding to this change in the Catechism, Edward Feser writes that
The Church has always taught, clearly and consistently, that the death penalty is in principle consistent with both natural law and the Gospel. This is taught throughout scripture—from Genesis 9 to Romans 13 and many points in between—and the Church maintains that scripture cannot teach moral error.
For those who dissent from Pope Francis’s teaching on capital punishment, the apparent Scriptural basis for capital punishment is significant. In the Scriptural argument for the morality of the death penalty, Genesis 9, which narrates God’s covenant with Noah, plays a particularly important role precisely because it is addressed through Noah to humanity as a whole rather than narrowly to the Israelite theocracy. Genesis 9 would seem to ground the death penalty as a common principle of the Natural Law and thus would make it be applicable and theoretically usable by all human societies.
The critical verse to which Feser refers, and from which he derives the title of his and Joseph M. Bessette’s book on the subject, is Genesis 9:6: “Whoever sheds the blood of a human, by a human shall that person’s blood be shed; for in his own image God made humankind” (NRSV). At first glance, this verse appears to be straightforward in its meaning. Those who violate the sanctity of the divine image in humanity through murder are to be punished by a human-enacted death penalty. The problem is that this translation of the critical phrase “by a human”—though ubiquitous in English versions—might not represent what the Hebrew text actually says.
The translational problem surrounds the very part of the passage that apparently entails the death penalty: “By a human shall that person’s blood be shed.” To explain this requires venturing into the weeds of both English and Hebrew grammar. In the English translation of Genesis 9:6, the verb “be shed” is in the passive voice and the agent of the action of that verb is expressed by a prepositional phrase “by a human.” Expressing the agent of a passive verb in English is perfectly grammatical and very common.
Classical Hebrew, by contrast, almost never expresses the agent of a passive verb. In fact, the authentic existence of any examples of passive agent with this kind of verb is debated by grammarians. If they do exist, they are rare. Of the hundreds of passive verbs in the Hebrew Bible, the grammarians can find only a handful of possible cases where the agent of a passive verb is explicitly expressed.
The translation “by a human shall that person’s blood be shed” is not strictly impossible, but given the norms of Classical Hebrew grammar, it should be viewed as prima facie unlikely especially since there is a much more plausible translation that is contextually appropriate and grammatically mundane. The phrase in question employs the Hebrew preposition b-, which has a variety of functions and senses. One of the regular senses of b- is to express price or exchange, and this use gives a sensible meaning to the passage. It is not “by a human shall that person’s blood be shed” but “for the human shall that person's blood be shed.” The prepositional phrase does not express the agent who sheds the murderer’s blood; it asserts that the murderer's blood is shed for the human that the murderer killed.
At this point, a detractor might fault this argument for pedantry. Perhaps the traditional translation is wrong, but what else could the passage refer to other than the death penalty? Even if Genesis 9:6 does not spell out that the murderer’s blood is to be shed “by a human,” surely the context implies that the murderer will be put to death by a human, right?
In fact, context supplies another, perhaps initially surprising, implied agent responsible for shedding the blood of the murderer. We need search the context no further than the immediately previous verse, Genesis 9:5: “But indeed I will seek your blood for your lives. From every beast I will seek it. From the hand of man, each man for his brother, I will seek the blood of a man” (my translation).
In several contexts, “to seek the blood” or simply “to seek” with God as subject means quite simply “to avenge.” Thus the NRSV translates “May the LORD see and seek” as “May the LORD see and avenge” (2 Chron 24:22), and “For he who seeks blood is mindful of them” as “For he who avenges blood is mindful of them” (Ps 9:12). The same sense applies in Genesis 9:5, which should be rendered: “But indeed I will avenge your blood for your lives. From every beast I will avenge it. From the hand of man, each man for his brother, I will avenge the blood of a man” (my translation).
As part of the covenant with Noah, God institutes several changes in the world and his own relation to it. He fundamentally changes the relationship between humanity and animals, giving animals an innate fear of humanity (Gen 9:2), and allowing the consumption of meat while forbidding the consumption of blood (9:4). In addition, God commits himself in Genesis 9:5 to a mysterious mode of intervention in the world in which somehow—he does not say how—he himself will intervene to avenge any creature, man or beast, that violates the sanctity of human life. This commitment to avenge the blood of any manslayer interprets the following verse, Genesis 9:6, and provides the agent that the grammar does not specify. Who will shed the blood of the murderer? God himself.
Genesis 9:5–6 raises important questions that the text does not address. How is it that God will avenge the blood of both beast and man? Here, as frequently in Scripture, he simply does not say. But the basic idea is widespread in Scripture. Deuteronomy 29:20–21, for example, contains the promise that when an individual—as opposed to the whole nation—violates the covenant, God will single that individual out for divine punishment. God will “single that person out” and “blot their name out from under heaven.” Will that person simply drop dead? Will they go into exile? The text does not say, but it does say that in one way or another, God will carry out the judgment. The wisdom literature is full of assurances that the wicked will get what is coming to them, and Ezekiel asserts as clearly as possible: “the person who sins shall die” (Ezek 18:20). Genesis 9:5–6 belongs in this strand of thought in insisting that God will ensure that the murderer is punished.
The supposed support Genesis 9:6 provides for proponents of the death penalty (and critics of Pope Francis) is not as straightforward as often supposed. Both the grammar and context point to this verse not being about the human-enacted death penalty at all, but rather about God’s own prerogative in executing judgment. If enlisted in arguments about capital punishment at all, this verse could in fact be enlisted in arguments against it.
Genesis 9 gives no provision for humans carrying out the execution of murderers. God alone here reserves the right to enact judgment on the murderer. The words of Genesis 9:6, therefore, can be read as expressing the same general principle contained in Deuteronomy 32:35 and quoted by St. Paul: “Do not seek vengeance, beloved, but give place for wrath, for it is written ‘vengeance is mine. I will repay, says the Lord.’” (Rom 12:19).
These observations on Genesis 9:6 do not, of course, settle the question of the morality of capital punishment or how Pope Francis’s revision of the Catechism should be understood in relation to previous Church teaching. But they do entail that if support for the death penalty is to be found in Sacred Scripture, it should be sought outside the covenant with Noah in Genesis 9.
 Edward Feser and Joseph M. Bessette, By Man Shall His Blood Be Shed: A Catholic Defense of Capital Punishment (San Francisco: Ignatius, 2017).
 See for example Bruce K. Waltke and M. O’Connor, An Introduction to Biblical Hebrew Syntax (Winona Lake: Eisenbrauns, 1990), 383, 385 who consider the expression of the passive agent in Niphal verbs to be real but “rare,” and compare Dennis Pardee, review of An Introduction to Biblical Hebrew Syntax, by Bruce K. Waltke and M. O’Connor, Journal of Near Easter Studies 53 (1994), 151, where in the midst of an overall very positive review of Waltke and O’Connor Syntax, Pardee criticises their discussion of the passive agent as an imposition of an Indo-European perspective on a Semitic language and provides an alternative analysis of their examples of expressed passive agency. See also Paul Joüon and T. Muraoka, A Grammar of Biblical Hebrew (Rome: Biblico, 2006), 454 who state “In Hebrew (and classical Semitic languages in general) the marking of an agent with a verb morphologically marked as passive is rather limited in scope when compared with many Indo-European languages.”