The Government of the Solarians was established by the Colonist Papers shortly after the arrival of the Korolev. It is a federal non-partisan directorial republic with thorough elements of direct democracy. It is made of The Council (executive branch) is one of three branches of government which includes the Assembly (legislative branch), and the Hall (judicial branch). The Council is made up of elected officials from various districts and regions across their adoptive homeworld. The Council includes ministers usually picked by the Chancellor, while the Assembly is made up entirely of elected officials and the Hall is predominantly made up of appointed judicial figures. The Council yield great power, though the Assembly ratifies all laws devised by the Chancellor and the Council. It is also able to veto provisions made by the Chancellor. There is no head of state, the Council members are all the head of state though the Chancellor leads the group and is elected to his position by the majority of Solarian citizens. The Vice Chancellor is elected separately, he often leads the Council while the Chancellor presides over both the Assembly and the Council. The Assembly is a unicameral legislative body. The Chancellor's immediate administration is made up of his presidential aide, Chief of Staff, the Vice Chancellor, the Council, his military advisor, science advisor and the Commandant of the Stellar Corps.
Together with the Assembly and the Hall, the government determined that the official term for Korolev colonists would be Solarian. As it was decided that the only unifying cultural identity was that all colonists came from the Solar System and originally native to the 23rd century.
Each colony runs themselves independently but an overarching federal government allows more collaboration and speedy trade. Modeled on the US government and parliamentary systems.
The Solarian government is often referred to as The Union.
http://en.battlestarwiki.org/wiki/Government_of_the_Twelve_Colonies