The Matter: While the Church does not possess the authority to judge a Pope, it does possess the competency and the right to judge whether or not a proposition professed by a Pope is materially heretical. This is an objective judgment, and therefore makes no difference if the proposition was professed by a pope or a non-pope. If any person (Pope or not) was to proclaim, for example, that “the old Covenant was never revoked by God” (45), or that “the resurrection of the body does not mean the resurrection of the actual physical body, but only the resurrection of the person”, the Church, or any Catholic who knows his Faith for that matter, can judge the statement to be heretical. Such a “judgment” would not constitute an inappropriate judgment of the person, since it is only an objective judgment of the proposition itself. Therefore, a council can certainly judge whether or not the material aspect of a teaching professed by a pope is heretical, but this objective judgment does not yet determine if the Pope himself is a heretic, since the second element, pertinacity, must also be established.
The Form: Establishing pertinacity is more difficult since it involves something that exists within the internal forum (the realm of conscience). If a person suspected of heresy does not openly admit that he rejects a Catholic dogma, pertinacity must be “drawn out” for it to be established with sufficient certainty.
45) Cf. Council of Florence, Cantata Domino, Denz. 712; and Mystici Corporis Christi, Pius XII, #29 - 30)