PeterZ wrote:Empires are not necessarily aristocracies or even monarchies. They are a form of government that exercises authority over a collection of states or countries. I can see an Empire as being very similar to a federal system of a republic where the member states are different enough that their local form of government is very different from other member states/countries.
I can agree on an empire not needing to be an aristocracy (the Kingdoms of Sweden, Norway and Denmark, for example, have kings but no aristrocracy), but I won't on a monarchy. Even if a figurehead, an empire is defined by there being an emperor. Or at least there having been one in the past (see the Klingon Empire, that hadn't had an emperor for 500-800 years). And another example from Star Trek is the Romulan Empire, which we saw ruled by a Praetor but whose emperor we've never seen on TV (the empress makes an appearance in one of the "A Time To..." books). On the other hand, in Babylon 5 we had a Vorlon Empire whose emperor we never saw and a Centauri Republic whose emperors we did see... (Turhan, Mollari and Vir).
That doesn't mean it's a hereditary monarchy either. The emperor might be elected, like the Holy Roman Emperor was, by the Prince Electors. OF course, that brings the saying that the Holy Roman Empire was neither Holy, nor Roman, nor an Empire...
As an example, let's assume the Sarthians for a planetary parliament based on their aristocracy for the upper house and clans for the lower house.
Further assume that one other civilization is a representative republic more like the current US but composed of a timocratical upper house and a religiously based lower house that represents a myriad of religions.
So, as we can see the PU of Earth can send representatives to the Terran Empire that consists of vastly different member planetary nations. Each of which governs itself in distinctly different ways, but owes allegiance to the Terran Empire's authority.
That's entirely possible. An extra level of government, above that of the planet and/or system, which is characterised by a constitutional, possibly elective, monarchy. If that's an elected emperor, that might also be both head of state and head of government. With lifespans measured in centuries, it wouldn't be out of the question that the head of state be elected for 50 T-years, a period longer than most monarchs have enjoyed so far on Earth.
Weirder things have happened. The King of France and the King of Spain used to be co-kings of Andorra. But for a couple of decades in the 20th century, neither Spain nor France had kings (Spain now does again). So the President of France is co-king of Andorra with King Phillip VI of Spain.