The Imperial Senate, also referred to as the Galactic Senate or the council, was the nominal legislative assembly of the Galactic Empire. It held no actual power, but was a de jure continuation of the Galactic Senate of the Old Republic, which was reformed into an autocratic regime when Supreme Chancellor Sheev Palpatine declared himself Galactic Emperor.
Many of the Imperial citizenry believed that the Emperor was indeed restoring stability to the galaxy, after he vowed to end corruption in the Senate. However the Senate began to grow weaker as planetary governors assumed more responsibility over their territories, with most Senate decrees becoming repeatedly ignored by the Imperial Military. In truth, this ploy was part of the Emperor’s need to preserve order and by extension, maintaining the Imperial Senate until the Death Star was completed.
In 0 BBY, the Imperial Senate was disbanded after the capture of Princess Leia Organa of Alderaan nineteen years after the formation of the Empire. With Organa being a senator who supported the growing Rebellion against Palpatine’s absolute rule, the Emperor used the incident to cast doubt unto the loyalty of the assembly. As such, the Senate was dissolved, with its former prerogatives handed down to the regional governors and the military.