In the United States, governmental power is divided vertically between nation and states and horizontally, at the national level, among the executive, legislative, and judicial branches. The Constitution leaves the lines of demarcation deliberately imprecise. Thus, from the beginning it was easy to predict that among those holders of power there would be tension (at least), conflict (probably), or total collapse (a possibility). The miracle of the American governmental system, with just this complexity and lack of definition, is the fact of its survival. It is not at all surprising that there have been a number of crises, some of which have seemed to imperil the whole edifice.
Robert B. McKay,
Court, Congress, and Reapportionment,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol63/iss2/4