The United Citizen Federation is a unified government of Earth, the Solar System planets and other territories and colonies.
Born from The Disorders, the global conflicts that happened during the 21st and 22nd century, the UCF follows a republic-like, parliamentary system of government, based in Geneva. It's ruled by the Federal Council in most of matters, except the military.
All Federal Council members are selected from the pool of national governors within each star system under the jurisdiction of the Federation. Each Council member is able to cast a single vote pertaining to all matters directly affecting the Federation (with the notable exception being security). A 60% majority vote is required in order to garner approval for all policy decisions.
Every government position within the Federation (from the most junior member of a Council member's staff to the Council members themselves) can only be filled by a Citizen. Civilians are unable to apply for any government position given that they have not yet proven they will keep the interests of the Federation first and foremost within their heart, defending them with their life if necessary. Citizenship (or franchise) is earned by civilians primarily through a voluntary term of service with the Federal Service of no less than two years (including swearing an oath to that effect).
Direct control of the main branches of the Federal Armed Services are placed under singular command of a Sky Marshal during periods of declared war.