The Star League is a collection of individual Houses; there is a hereditary Emperor who is basically the head of the most powerful house. The heads of the other Houses hold Ranks which approximate that of Feudal Society. Each House makes its own laws and enforces them within their Spacial Holdings. There are no independant planetary governments within any declared House space.
The overall society of the League is a Feudal one. So if you aren't Nobility or a powerful merchant you are effectively nobody. Each planet (or group of planets) is under the control of a Baron, or Marquis.
There are six distinct Classes within the League; Nobility, Warriors, Merchants, The Ben Gezerette, Citizens and Non-Citizens.
The Star League is made up of approximately 85% Human or Humanoid.
The Navigators Guild is very powerful in the League, and every interstellar ship within the Leagues borders will have at least one navigator on board.