Federations are some of the most popular government types in fiction.
A federation is a union of self-governing states or regions that give up some of their freedom for a national government and the advantages it offers. A constitution outlines the status and division of power and cannot be altered by political powers, the federal government, or the regions in the union. One goal is greater stability, especially economic, but if the economy of one state experiences severe troubles, it can threaten the stability of them all. Territorial disputes are also resolved with the agreement, which also creates greater uniformity between disparate states.
The states have some sovereignty over themselves but nothing at the federal level or with other foreign powers. They have some rights to control local laws and administer their own affairs. Some states may have more autonomy than others, possibly because they joined a federation sooner, before the constitution changed. Federations can also provide a common military front to shared enemies. A federation is helpful in managing a very large area due to the ability of the small states (sometimes called provinces) to manage their more local affairs. Membership in the federation is not voluntary.
A challenge for all federations is that individual states sometimes have opposing ideas about what they can do and the central government must find a way to resolve this. Failure to do so can lead to civil war, states seceding, or even states being expelled. In extreme cases, the federation can collapse. One example is the United States Civil War, where southern states believed the constitution provided the right for slavery. Other states and the federal government disagreed. This caused the southern states to attempt seceding (to create a confederation, explained below). Seceding is not allowed in a federation and led to civil war as the federal government attempted to bring the southern states back in line. No foreign country recognized the south’s Confederation of the United States as being sovereign.
Federations, like Canada, sometimes do not include “federation” in their name, but others will. Titles include federation, federal republic, confederation, dominion, kingdom, and union. In other words, we can’t always tell what form of government a sovereign power has by its title.
A unitary state is similar to a federation except that the federal government can eliminate the autonomy of the states. Their formation is also different, as a federation comes together from independent states joining forces. A unitary state originates from a pre-existing central government granting more autonomy to previously dependent states. What the government giveth, it can taketh away. These subdivisions can be created and abolished by the central government at will. Laws can also be forced on the states or taken away. Sometimes the states cannot create any of their own laws.
These details may be the sort of thing we and our audience don’t care about, so we could ignore unitary states as an option for our sovereign powers and just have them be a federation instead, partly because we’ve all heard “federation.” Fewer have heard of “unitary state,” requiring explanation that is likely dry. If we use a unitary state, we may not want to call it one to avoid that reaction. This gives us the best of both worlds: a unitary state without reader confusion. If our story ever involves the government giving or removing rights to a state, then we can admit its form of government.
The United Kingdom is a unitary state.
A confederation is a group of sovereign powers who form a permanent union so as to act together against other states. Membership is voluntary, unlike a federation. Any agreements made by the confederation are not binding until the member states enact laws in accordance with those agreements. The actual confederation has no real power and any changes to its constitution require a unanimous vote. The formation is usually by treaty, but a constitution will be created shortly thereafter. One confederation might be quite different from another, meaning we have some freedom to create the rules of one; some will be stricter, like a federation.
Switzerland, Canada, Belgium, and the European Union are confederations.
In an empire, multiple sovereign powers are ruled by a single power via coercion. The individual powers are still self-governing because the central government allows it, similar to a federation. An empire can include territories across the sea and other territories not adjacent to it, like the British Empire. Sometimes a ruler, such as a king, names himself emperor, making his territory automatically an empire, even when it doesn’t fit the details outlined here (it’s still a single sovereign power).
In addition to controlling by conquest, an empire can gain control by exerting pressure due to having an advantage of some kind. This can include superior economics that make another sovereign power subservient to it. Using force requires keeping soldiers in each country. This limits options for further conquest, so other forms of coercion are attractive.
A weak state may also seek to be annexed by an empire for protection and other advantages such as trade. Imagine being the ruler of a kingdom sandwiched between an empire and a wasteland of nomads known for violent conquest; we might want the empire’s protection from the barbarian horde. This protection comes at the expense of current autonomy but is better than the alternative of being destroyed. In SF, a planet could be blockaded by space ships and prevented from interplanetary trade unless it joins the empire blockading it.
Due to this absorption of other countries, an empire includes multi-ethnic peoples and will typically force its culture on all its territories to consolidate its hold. When an empire fails, it often breaks into pieces based on these cultural and ethnic divisions, and the previously independent states (prior to the empire) don’t necessarily return to what government they were before the empire. An empire’s collapse is often catastrophic for its former territories, leading to enormous upheaval and uncertainty. If we want traveling characters to experience unexpected challenges wherever they go, an empire’s recent collapse provides believable chaos across many areas.
An empire can become a federal republic or a more loosely bound commonwealth of nations all governed by the previously dominant nation. For example, Britain still governs states that were part of its empire. The impact of having been part of an empire is long lasting even when full independence is achieved. Economic and cultural changes take root more deeply the longer a state was part of an empire.
Examples include the Roman Empire and British Empire.