The Imperial Senate or Imperial Congress was the de jure legislative body of the Galactic Empire, though in fact it held little real authority. Instead, it served mainly as an advisory body to EmperorPalpatine. The Imperial Senate was the successor to the Galactic Senate of the Republic, which was reformed when then–Supreme Chancellor Palpatine declared himself sole ruler.
On the whole, however, the transition from Galactic Senate to Imperial Senate went quietly and without major incident. Emperor Palpatine did not want to risk tarnishing his public support by making an open grab for power, so he allowed the organization to continue to nominally exist, though it had been gutted of any real functional power. Under advice from Padmé Amidala shortly before her death, Senators Organa and Mon Mothma, along with other Senators from the Delegation of 2000, did not directly confront Palpatine's declaration of a Galactic Empire. Realizing they had already lost, and that further resistance would only be seized upon by Palpatine as justification for dismantling what little remained of the Senate, they determined that their best remaining option was to bide their time in silence.
Although at the time of the Empire's formation a majority of senators were loyal to Palpatine, the Imperial Senate was still a prime (if often clandestine) source of resistance to Palpatine's authority, and despite its changes, came to be known as the "last remnants of the Old Republic." Certain Senators—many of whom later joined the Rebellion—were known for using the Senate as a platform to voice proposals attempting to moderate Palpatine's rule, although always under the guise of perfect loyalty.
"The Imperial Senate will no longer be of any concern to us. I've just received word that the Emperor has dissolved the council permanently. The last remnants of the Old Republic have been swept away."
Hologram of Emperor Palpatine, taken from the speech in which he announced the disbanding of the Senate
In 0 BBY (35:3:5), Palpatine ordered the Imperial Senate to be shut down "for the duration of the emergency," ostensibly due to the widespread dissemination of the Declaration of Rebellion over the previous months. It was never revived. To fill the open void in the Imperial government, COMPNOR'sSelect Committee stepped up to the role of overseeing the vast Imperial bureaucracy and the Imperial Ruling Council became the central leadership within the Empire, while the Moffs and Grand Moffs retained direct control over their territories.
According to the Bureau of Operations of Imperial Intelligence, the Rebel Alliance managed to rescue many former Senators who were willing to use their political influence to oppose the Empire. To prevent these politicians from openly supporting the Rebellion, Imperial Intelligence sent teams to attack the Senators' hideouts.[1]
Discontented Imperial Senators form the Rebel Alliance
Besides the name, the organization differed somewhat from its Republican forebear. Whereas the Galactic Senate had held both legislative and executive power, the Imperial Senate held only legislative power—though most of this power was in the hands of the Emperor, as he was the overall ultimate authority. Despite such, the Imperial Senate still held limited judicial authority, enough to try high ranking officials in the Empire and, possibly, handle cases tied into the Supreme Court. The Emperor allowed the Senate to provide him counsel in enacting new laws. It also had nominal oversight of the Imperial bureaucracy and worked on the Imperial budget. However, the Emperor made it clear that his judgments would be final: Imperial decrees would be issued without debates, court proceedings, or Senatorial overrides. The Emperor could also call and dismiss the Senate at will. The Senate could also pass amendments to the Imperial Charter and apparently had at least nominal oversight of the Imperial Military.
The day-to-day head of the Senate was no longer the Vice Chair, but the Grand Vizier as President of the Senate. The Senate was, at least in theory, responsible for choosing a new Emperor upon the death or abdication of the current holder of the throne. As Palpatine had no intention of ever dying or abdicating, this power was merely a formality.
The Imperial Senate was made up of groups of congressmen: Senators and representatives, representing sectors in the Empire. Some were elected directly, while others were appointed by a planet's ruler.
Because of "Human High Culture," most of the alien Senators were replaced by Humans, who ended up representing worlds that were entirely non-human. However, alien senators were not unheard-of, especially in the early days of the Empire.
Palpatine's transformation of the Galactic Senate into the Imperial Senate mirrors how the Roman Republic was transformed into the Roman Empire by its first emperor, Augustus. Rather than risk further confrontation with the Roman Republic's Senate, Augustus allowed the Senators to continue meeting, but they had been stripped of any real executive power, continuing as little more than an advisory council which he could simply ignore at his leisure.