Tribunicia potestas (tribunician power) refers to the rights granted to Rome’s tribuni plebis—including sacrosanctity, that is, personal inviolability while in office—and ...
Tribunicia potestas (tribunician power) refers to the rights granted to Rome’s tribuni plebis—including sacrosanctity, that is, personal inviolability while in office—and (later) to the claim by Roman emperors to the plebeian tribunes’ privileges, a status which they employed to reckon their own years of rule and also publicly designate a successor. In official titulature the emperors commonly list it second among their distinctions (with number of continuous years held, thus functioning akin to a regnal year), after the office of pontifex maximus and before the number of imperatorial acclamations and consulships (see imperator, consul).
Tribunes originally received their prerogatives to defend and support the plebs, which essentially formed a “state within a state” in the Roman polity. But already in the mid-4th century bce, tribunes were using their powers more generally in senatorial politics; by the early 3rd century bce, the tribunes also had made themselves indispensable to the smooth functioning of the Roman legislative process. Though the plebeian tribunate lasted well into the imperial period, its practical and political importance faded swiftly with the demise of the Republic. Already in 48 bce the patrician Caesar received an extraordinary grant of tribunicia potestas (later confirmed for life) without having to hold the office of the tribunate itself. In 36 bce his adopted son Octavian seized upon the precedent in his struggles as triumvir; in the constitutional settlement of 23 bce as Augustus he formalized his tenure of annually renewable tribunicia potestas, henceforth reckoning his years of rule by it. This assumption of tribunician power, alongside enhanced imperium, definitively established the legal basis of his principate, and that of subsequent emperors for at least the next three and half centuries. Augustus also secured grants of tribunicia potestas for his successive sons-in-law to mark them off for dynastic succession—first Agrippa, then Tiberius. Here too he set a productive example for future emperors.