This is interesting. In my original B.A. thesis work on conciliarism (some of which is as yet unpublished), I developed the idea of multiple streams of thought about authority in Western Christendom throughout the Middle Ages. The sources I had at hand at that time indicated that feudalism, particularly influenced by Germanic customs, incorporated the right of subjects to diffidatio, resistance to unjust leaders and laws.
So far, so good: long before the Protestant reformation Medieval Christendom recognized the right of abused subjects to resist their abusive leaders.
Today, reading about ancient Roman virtues, I discovered that a prime one was fides, faithfulness. What this entailed was not just personal honesty and a proper regard for one’s legal and financial obligations, but also the requirement of those in power over others, the patrons (patroni), to keep faith with their subordinates, the clients (clientes). Failure on the part of a patron to keep faith with his client was considered a grave offense against the gods and the community, and it had two main results: (1) the patron was put under a curse, and (2) the client gained the right to resist his patron. In extreme cases, divine wrath could be a consequence for an unfaithful patron.
So there it is. We don’t have to wait for Medieval Christendom and Germanic notions coming in from the outside to justify a key principle of Western political thought, resistance to tyranny. Nor do we have to consult sources outside of Roman law and cultural expectations. The ancient virtue of fides, built into the warp and woof of Roman society from very early times, came into the Christian order of things along with many other Roman things, and it can quite well do the conceptual and practical work of constructing a case that bishops and other prelates are not absolute authorities under God. If they break faith, they forfeit their right to expect obedience from their subjects, and what’s more, they draw upon themselves communal, and perhaps even divine, wrath.
Sic semper tyrannis: thus always to tyrants.