The Roman Senate
The Senate was the chief governing body of the Roman republic for a period of 400 years. Originally it was the advisory council of the kings, and on the expulsion of the kings in 510 BC it continued to act, in theory, as adviser to the magistrates. In practice, however, although its decisions were only recommendations, they came to have the force of law. In time this caused difficulty, since after 287 BC the popular assembly was officially the sovereign body of Rome.
The Senate originally numbered 300, later 600. Method of entry varied- at first senators were chosen by the kings, then by the Consuls, then by the Censors. From the time of Sulla election to the quaestorship carried automatic entry to the Senate, so that the composition of the Senate was indirectly subject to popular election. Membership was for life, though the censors could remove those guilty of misconduct. Under the Empire the Senate remained important, as a source of administrative talent and an expression of public opinion, until the 3rd century AD when the emperor Gallienus ruled that senators could not hold military appointments. The Senate retained some prestige and privileges, but its political influence went into a continuous decline.