there was a time in rome when laying a hand on a certain politician — pushing him, striking him, even shoving past him — turned the assailant, automatically and lawfully, into a dead man. it was no rhetorical threat: it was the literal workings of one of the strangest and most powerful institutions the republic ever devised.
that office was born of pressure. after the great secession of the plebs to the sacred mount, around 494 bce, the aristocracy had to create a magistracy reserved for plebeians: the tribune of the plebs. but an office written into law counted for little against the real power and the weapons of the elite. the plebs knew it, and so it did not settle for a title: it armoured the post with a status that bordered on the supernatural.
they invested their tribunes with a status called sacrosanctitas: they were, literally, sacred.
the sacrosanctitas worked as a legal-religious shield. anyone who dared lay hands on a tribune became, by that act alone, sacer: accursed, consecrated to the gods as an offering. and a man who was sacer had lost all protection of the law. killing him was not only no crime — it was almost a civic duty: any roman could put him to death with impunity, without trial or process, and his goods were consecrated to the gods — in the tradition, to ceres — rather than confiscated by the state. the entire plebs swore collectively to enforce that sanction. it was political immunity backed not by the force of the state, but by the organised fury of the people.
with his life guaranteed, the tribune could do something unheard-of: stand before power and stop it. his decisive weapon was intercession. he could interpose his person between a citizen and an abusive magistrate — the auxilium, the “aid” given to the oppressed — and, above all, he could oppose, by means of the intercessio, the decisions of those in office and bring them to a dead halt. from that second prerogative comes the single word that later latin would fix as the symbol of every political deadlock: veto, “i forbid”. it is worth noting that in these earliest times the technical term was the intercessio, and that “veto” took hold as a label only later; but the translation captures its effect exactly. one tribunician voice was enough to freeze the machinery of the state.
that power, however, had carefully calculated limits: it was above all defensive and negative — the tribune could prevent, veto, protect, but he could not command armies or govern provinces like a consul. his authority stopped at the pomerium, the sacred boundary of the city, where the people he defended were, and dissolved on campaign. and, above all, the tribunes could cancel one another out: since there were several of them and intercession also worked among them, it was enough for the aristocracy to win one of them over for his veto to block the rest. the plebs’ shield had, therefore, a crack through which patrician money and influence would slip again and again. it was a formidable counterweight, but not a sword.
even with those limits, the result was a constitutional piece without parallel: a magistrate whose body was untouchable and whose word could halt the government. the tribunate gave the plebs, for the first time, real defensive power, and it became the engine of its political rise over the next two centuries. its shadow would reach far: in the late republic, the great reformers and agitators — from the gracchi onwards — would use the tribunate as a lever to shake the whole order, and the emperors would end up appropriating the potestas tribunicia as one of the foundations of their authority. what the plebs invented as a shield became one of the keys to power in rome.
the aristocracy, however, did not give up. if it could no longer bend the plebs by law or by force, one subtler weapon remained: money. by buying the loyalty of the poorest, binding them with favours and loans, the patricians would find a way to turn a good part of the people into an obedient clientele, neutralising from within the very power that had just slipped from their hands.
