“In conscience one has the right to make such a judgment (of manifest formal heresy) because it is a legitimate matter of conscience, and can be known with certitude. All the canons, and teachings against privately judging superiors and prelates do not refer to judgments of conscience, such as the judgment concerning the manifest heresy of one’s superior, when it can be known with certitude; but rather, they prohibit judgments that require jurisdiction; and explain that private individuals do not possess the requisite jurisdiction for rendering an official judgment, and therefore they may not presume to judge their superiors juridically, and depose them with force of law. However, the right of conscience to judge privately as a matter of conscience in such cases as that of manifest heresy pertains to divine law, since such judgments of conscience are sometimes necessary for salvation; and such a right is acknowledged in Canon Law: ‘Can. 748 § 1. All persons are bound to seek the truth in those things which regard God and his Church and by virtue of divine law are bound by the obligation and possess the right of embracing and observing the truth which they have come to know.’ Indeed, the Salza/ Siscoe objection that the making such a judgment is forbidded to the private individual who must wait for the public judgment of the Church, and that asserting this right it is an exercise of the Protestant principle of Private Judgment, is not only false, but it effectively nullifies the Rule of Faith which safeguards the conscience of the individual.”
Kramer, Paul. To Deceive the Elect: The Catholic Doctrine on the Question of a Heretical Pope (Kindle Locations 736-747). Kindle Edition.