Princeps senatus
The Roman emperors merged the princeps senatus' prerogatives with their own, although there are occasional mentions of distinctive principes during the later Empire.
[5] By the middle republic,[6] the princeps senatus was the most prestigious position in Rome and had adduced further privileges: he moved all routine senate business, having power to have his input directly moulded into them by choosing their wording.
[8] The position of princeps senatus was not defined by law (lex), but by tradition (mos), which makes it more difficult to follow its evolution.
[18] The most probable candidate is therefore Quintus Fabius Maximus Rullianus, chosen by the censors of 275, whose lectio left a mark in ancient sources.
[19] In 209 BC, the censor Publius Sempronius Tuditanus went against the tradition and appointed Quintus Fabius Maximus Verrucosus instead of Titus Manlius Torquatus, the senior ex-censor.
[23][24] However, Sulla would probably not have demoted his close ally, the princeps Lucius Valerius Flaccus, who had enabled his appointment as dictator though the lex Valeria.
[28] Pierre Willems and Francis Ryan have suggested that Cicero may have been the last princeps senatus of the Republic, appointed after April 43 by his fellow senators.
Such restoration of this ancient office was part of "diehard republicans"' propaganda against Mark Antony, whom Cicero had violently attacked in his Philippicae.
If the post was limited to certain gentes, the Julii were possibly ineligible, and Augustus was not yet then one of the customary candidates (senior ex-censors).
[31] In the emperor's absence, it is possible that a senator was granted the privilege of holding this role when the Senate met; the notoriously unreliable Historia Augusta claimed that during the Crisis of the Third Century, some others held the position; in particular, it stated that the future emperor Valerian held the office in AD 238, during the reigns of Maximinus Thrax and Gordian I, and he continued to hold it through to the reign of Decius.
