The doctrine of the separation of powers was adopted by the Convention of 1787, not to promote efficiency but to preclude the exercise of arbitrary power. The purpose was, not to avoid friction, but, by means of the inevitable friction incident to the distribution of the governmental powers among three departments, to save the people from autocracy.

Louis Brandeis (1856-1941) American lawyer, activist, Supreme Court Justice (1916-39)

Myers v. United States, 272 U.S. 293, (1926) [Dissent]