The office of tribune in the ancient Roman Republic had been instituted to function as an inviolable guardian of the people. The person of the tribune was considered sacrosanct; he could not be removed from office or hindered in any way, he could veto any act of the Senate with binding force, and if any man laid hands on him that man was to be killed.
But in 133 B.C., when Rome was beset by enormous corruption of unethical wealthy men preying on the people, often by creative usurpation of the law, the tribune Tiberius Gracchus (168-133 B.C.) took the unprecedented step of having the people depose another tribune, Octavius, who was acting in concert with the wealthy against the people. In the name of the spirit of the law, Tiberius Gracchus justified this seemingly revolutionary action in this way:
But beginning to understand that the course he had taken with Octavius had created offence even among the populace as well as the nobility, because the dignity of the tribunes seemed to be violated, which had always continued till that day sacred and honourable, he made a speech to the people in justification of himself; out of which it may not be improper to collect some particulars, to give an impression of his force and persuasiveness in speaking. “A tribune,” he said, “of the people, is sacred indeed, and ought to be inviolable, because in a manner consecrated to be the guardian and protector of them; but if he degenerate so far as to oppress the people, abridge their powers, and take away their liberty of voting, he stands deprived by his own act of honours and immunities, by the neglect of the duty for which the honour was bestowed upon him. Otherwise we should be under the obligation to let a tribune do this pleasure, though he should proceed to destroy the capitol or set fire to the arsenal. He who should make these attempts would be a bad tribune. He who assails the power of the people is no longer a tribune at all. Is it not inconceivable that a tribune should have power to imprison a consul, and the people have no authority to degrade him when he uses that honour which he received from them, to their detriment? For the tribunes, as well as the consuls, hold office by the people’s votes. The kingly government, which comprehends all sorts of authority in itself alone, is moreover elevated by the greatest and most religious solemnity imaginable into a condition of sanctity. But the citizens, notwithstanding this, deposed Tarquin, when he acted wrongfully; and for the crime of one single man, the ancient government under which Rome was built was abolished for ever. What is there in all Rome so sacred and venerable as the vestal virgins, to whose care alone the preservation of the eternal fire is committed? yet if one of these transgress she is buried alive; the sanctity which for the gods’ sakes is allowed them, is forfeited when they offend against the gods. So likewise a tribune retains not his inviolability, which for the people’s sake was accorded to him, when he offends against the people, and attacks the foundations of that authority from whence he derived his own. We esteem him to be legally chosen tribune who is elected only by the majority of votes; and is not therefore the same person much more lawfully degraded when, by a general consent of them all, they agreed to depose him? Nothing is so sacred as religious offerings; yet the people were never prohibited to make use of them, but suffered to remove and carry them wherever they pleased; so likewise, as it were some sacred present, they have lawful power to transfer the tribuneship from one man’s hands to another’s. Nor can that authority be thought inviolable and irremovable which many of those who have held it, have of their own act surrendered and desired to be discharged from. (Plutarch, Tiberius Gracchus)
Note the repeated theme throughout this speech that those who are given the power of administering and upholding the law are themselves responsible to the law, and if they fail to perform their lawful duties they essentially depose themselves from their positions.
This is a theme which reappears time and again in Medieval Christian political theory, especially in the later Middle Ages. The intriguing thing is that this is a very old Roman idea (from the Republic), and it winds up being deployed against the newer Roman idea (from the Empire) that the prince is not subject to the laws, but himself makes them.
Especially in terms of the later Medieval battles between conciliarists and papalists, in which the former repeatedly argue that the pope’s power is derived from the Church and the Church may depose him if he attempts to wreck the Church, it seems that the Roman Republic comes back to haunt the Roman Empire.