In political science, it has long been a goal to create a typology or taxonomy of polities, as typologies of political systems are not obvious.[16] It is especially important in the political science fields of comparative politics and international relations. Like all categories discerned within forms of government, the boundaries of government classifications are either fluid or ill-defined.

Superficially, all governments have an official de jure or ideal form. The United States is a federal constitutional republic, while the former Soviet Union was a federal socialist republic. However self-identification is not objective, and as Kopstein and Lichbach argue, defining regimes can be tricky, especially de facto, when both its government and its economy deviate in practice.[17] For example, Voltaire argued that "the Holy Roman Empire is neither Holy, nor Roman, nor an Empire".[18] In practice, the Soviet Union was a centralized autocratic one-party state under Joseph Stalin.

Identifying a form of government is also difficult because many political systems originate as socio-economic movements and are then carried into governments by parties naming themselves after those movements; all with competing political-ideologies. Experience with those movements in power, and the strong ties they may have to particular forms of government, can cause them to be considered as forms of government in themselves.

Other complications include general non-consensus or deliberate "distortion or bias" of reasonable technical definitions to political ideologies and associated forms of governing, due to the nature of politics in the modern era. For example: The meaning of "conservatism" in the United States has little in common with the way the word's definition is used elsewhere. As Ribuffo notes, "what Americans now call conservatism much of the world calls liberalism or neoliberalism"; a "conservative" in Finland would be labeled a "socialist" in the United States.[19] Since the 1950s conservatism in the United States has been chiefly associated with right-wing politics and the Republican Party. However, during the era of segregation many Southern Democrats were conservatives, and they played a key role in the conservative coalition that controlled Congress from 1937 to 1963.[20][a]

Opinions vary by individuals concerning the types and properties of governments that exist. "Shades of gray" are commonplace in any government and its corresponding classification. Even the most liberal democracies limit rival political activity to one extent or another while the most tyrannical dictatorships must organize a broad base of support thereby creating difficulties for "pigeonholing" governments into narrow categories. Examples include the claims of the United States as being a plutocracy rather than a democracy since some American voters believe elections are being manipulated by wealthy Super PACs.[21] Some consider that government is to be reconceptualised where in times of climatic change the needs and desires of the individual are reshaped to generate sufficiency for all.[22]