The following comes from a December 16 In the Light of the Law blog post by Edward Peters:

No one in a position of ecclesial responsibility—not the Four Cardinals posing dubia, not Grisez & Finnis cautioning about misuses, and not the 45 Catholics appealing to the College, among others—has, despite the bizarre accusations made about some of them, accused Pope Francis of being a heretic or of teaching heresy. While many are concerned for the clarity of various Church teachings in the wake of some of Francis’ writings and comments, and while some of these concerns do involve matters of faith and morals, no responsible voice in the Church has, I repeat, accused Pope Francis of holding or teaching heresy.

That’s good, because the stakes in regard to papal heresy are quite high. Those flirting with such suspicions or engaging in such ruminations should be very clear about what is at issue.

First. Heresy is, and only is, “the obstinate denial or obstinate doubt after the reception of baptism of some truth that must be believed by divine and catholic faith.” 1983 CIC 751. Heresy is not, therefore, say, the failure to defend effectively specific truths of Revelation (though that might be negligence per Canon 1389); moreover, privately-held heretical views, even if they are leading to certain observable actions, are not in themselves actionable under law (Canon 1330).

Second. We can dismiss as impossible—indeed, as unthinkable thanks to the protection of the Holy Spirit—any scenario whereby a pope commits the Church to a heresy. See Ott, Fundamentals (1957) 287 or Catholic Answers tract “Papal Infallibility” (2004). However grave might be the consequences for a pope falling into heresy, the Church herself cannot fall into heresy at his hands or anyone else’s. Deo gratias.

Those two points being understood, the canonical tradition yet recognizes (and history suggests) that a given pope could fall into personal heresy and that he might even promote such heresy publicly, which brings us to some thoughts on those possibilities.

Setting aside a few who, relying on half-baked notions like “popes are not bound by canon law”, throw up their hands in despair at the prospect of a heretical pope and predict the End-of-the-World-as-We-Know-It, others, more reasonably, point to Canon 1404, which states “The First See is judged by no one”, and conclude that the only remedies in the face of a genuinely heretical pope are prayers and fasting. May I suggest, though, that canon law has somewhat more to offer than that.

Wrenn, writing in the CLSA NEW COMM (2001) at 1618 states: “Canon 1404 is not a statement of personal impeccability or inerrancy of the Holy Father. Should, indeed, the pope fall into heresy, it is understood that he would lose his office. To fall from Peter’s faith is to fall from his chair.”

While I suggest that Wrenn’s warning be read again, lest its startling impact be overlooked by the calm manner in which he expressed it, turning to the crucial question as to who would determine whether a given pope has fallen into heresy, Wrenn notes that it is not settled by Canon 1404 nor, I would add, is it settled by any other canon in the Code. But again, one may turn to canonical tradition for insight.

To be sure, all admit that in talking about popes falling into heresy we are talking a very remote scenario. Vermeersch-Creusen, Epitome I (1949) n. 340, “This sort of case, given the divine protection of the Church, is considered quite improbable.” Beste, Introductio (1961) 242, “In history no example of this can be found.” And the great Felix Cappello, Summa Iuris I (1949) n. 309, thought that the possibility of a pope falling into public heresy should be “entirely dismissed given the special love of God for the Church of Christ [lest] the Church fall into the greatest danger.”

But Cappello’s confidence (at least in the scope of divine protection against heretical popes) was not shared by his co-religionist, the incomparable Franz Wernz, whose summary of the various canonical schools of thought about the possibility of a papal fall from office due to heresy is instructive. After reviewing canonical norms on loss of papal office due to resignation or insanity, Wernz-Vidal, IUS CANONICUM II (1928), n. 453, considers the impact of personal heresy on the part of a pope (emphasis and citations omitted):

Through heresy notoriously and openly expressed, the Roman Pontiff, should he fall into such, is, by that very fact, and before any declaratory sentence of the Church, deprived of his power of jurisdiction.

In sum, and while additional important points could be offered on this matter, in the view of modern canonists from Wernz to Wrenn, however remote is the possibility of a pope actually falling into heresy and however difficult it might be to determine whether a pope has so fallen, such a catastrophe, Deus vetet, would result in the loss of papal office.

May that fact serve as a check against those tempted to engage in loose talk about popes and heresy.