The Theian Assembly

Led by a Prime Minister, the Imperial Theian Assembly is composed of elected political representatives from across the Empire, who gather periodically in the Imperial Senate Building on Imperial Centre to draft legislation before passing it to the Council of Governors for review and approval. The Council has the power to veto legislation and send it back to the Assembly for revision, however the ultimate power of veto rests with The Imperial Privy Council.

To become a High Senator of a sector one must first win election as a Senator within that same sector, then be nominated by the Sector Governor, and finally be appointed a High Senator by the Emperor. The Prime Minister is the High Senator who serves as the leader of the largest political party in the Imperial Assembly and therefore is not directly elected by the citizens of the Empire. Additionally, his ascension to the role must be personally confirmed by the Emperor. All High Senators are properly addressed as "Senator" or "High Senator", while the Prime Minister retains the right to be addressed as "Excellency". Upon retirement certain High Senators will be awarded a Barony within their sector as a gift for their service. More commonly, High Senators will receive an MSE or GSE depending on their seniority in the chamber, also as a personal recognition from the Emperor for their work.

The High Senator of a sector will additionally chair a sector-level council of his system Senators, and in his absence be replaced by his deputy, the Senator of the sector's capital planet.