The first great event which gave the plebs protection and political importance was the appointment of representatives called “tribunes of the people,”—­a privilege extorted from the patricians.  The tribunes had the right to be present at the deliberations of the senate; their persons were inviolable, and they had the power of veto over obnoxious laws.  Their power continually increased, until they were finally elected from the senatorial body.  In 421 B.C. the plebs had gained sufficient influence to establish the connubium, by which they were allowed to intermarry with patricians.  In the same year they were admitted to the quaestorship, which office entitled the possessor to a seat in the senate.  The quaestors had charge of the public money.  In 336 B.C. the plebeians obtained the praetorship, a judicial office.

In the year 286 B.C. the distinctions vanished between plebeians and patricians, and the term populus instead of plebs, was applied to all Roman people alike.  Originally the populus comprised strictly Roman citizens, those who belonged to the original tribes, and who had the right of suffrage.  When the plebeians obtained access to the great offices of the state, the senate represented the whole people as it formerly represented the populus, and the term populus was enlarged to embrace the entire community.

The senate was an august body, and was very powerful.  It was both judicial and legislative, and for several centuries was composed of patricians alone.  Its members always belonged to the aristocracy, whether of patrician or plebeian descent, and were supposed to be rich.  Under Augustus it required one million two hundred thousand sesterces annually to support the senatorial dignity.  The senate, the members of which were chosen for life, had the superintendence of matters of religion and foreign relations; it commanded the levies of troops; it regulated duties and taxes; it gave audience to ambassadors; it determined upon the way that war should be conducted; it decreed to what provinces governors should be sent; it declared martial law in the appointment of dictators; and it decreed triumphs to fortunate generals.  The senators, as a badge of distinction, wore upon their tunics a broad purple stripe, and they had the privilege of the best seats in the theatres.  Their decisions were laws (leges). A large part of them had held curule offices, which entitled them to a seat in the senate for life.  The curule officers were the consuls, the praetors, the aediles, the quaestors, the tribunes; so that an able senator was sure of a great office in the course of his life.  A man could scarcely be a senator unless he had held a great office, nor could he often have held a great office unless he were a senator.  Thus it would seem that the Roman constitution for three hundred years after the expulsion of the kings was essentially aristocratic.  The plebs had but small consideration till the time of the Gracchi.