"The principle, in short, which gives its form to our system of government is (to use a foreign but convenient expression) "Unitarianism", or the habitual exercise of supreme legislature authority by one central power, which in the particular case is the British Parliament. The principle which, on the other hand, shapes every part of the American polity, is that distribution of limited, executive, legislative and judicial authority among bodies each co-ordinate with and independent of the other which... is essential to the federal form of government."