Each stellar sector, in the final centuries of the Star Imperium, saw the ruling Moff share power in the sector with a sector assembly which was appointed by subsector assemblies. This continued under the United Planets. A sector assembly typically had 50 seats per Subsector.

Under the United Planets regime, each sector assembly elect one sector Moff and 25 members to the United Planets Assembly. In some cases, under the Politics in the United Planets era, the Monotheist Party and the Incarnate Party made inter-party deals where one party obtained the position of Moff while the other party obtained the majority of the sector's seats in the United Planets Assembly. In less frequent cases, the Incarnate Party made deals with the Freethinkers where the Freethinker assembly members supported an Incarnate Party candidate for Moff in return for 10 to 12 seats out of 25 seats the sector received in the United Planets Assembly on Alfheim.