However, a differentiation of the functions of different departments is an invariable feature of all written constitutions. The very purpose of a written constitution is the demarcation of the powers of different departments of government so that the exercise of their powers may be limited to their particular fields. In countries governed by a written constitution, as India is, the supreme authority is not Parliament but the Constitution. Contrasting it with the supremacy of Parliament, Dicey has characterised it as the supremacy of the Constitution." 574. A. V. Dicey, the celebrated propounder of the doctrine of the sovereignty of Parliament, had criticized Austin for frequently mixing up "legal sovereignty" and "political sovereignty" (See: Law of the Constitution by A. V. Dicey — 10th Edn. p. 72). He contrasted the British principle of "Parliamentary Sovereignty" with what was described by him the "Supremacy of the Constitution" in America. He observed (at p. 165). "But, if their notions were conceptions derived from English law, the great statesmen of America gave to old ideas a perfectly new expansion, and for the first time in the history of the world formed a constitution which should in strictness be 'the law of the land', and in so doing created modern federalism. For the essential characteristics of federalism — the supremacy of the constitution — the distribution of powers — the authority of the judiciary — -reappear, though no doubt with modifications, in every true federal state." He said (at p. 144) : "a federal state derives its existence from the constitution, just as a corporation derives its existence from the grant by which it is created. Hence, every power, executive, legislative, or judicial, whether it belongs to the nation or to the individual States, is subordinate to and controlled by the constitution." He wrote about the American Supreme Court (at p. 159) : "Of the nature and position of the Supreme Court itself this much alone need for our present purpose be noted. The Court derives its existence from the Constitution, and stands therefore on an equality with the President and with Congress, the members thereof (in common with every Judge of the Federal Judiciary) hold their places during good behaviour, at salaries which cannot be diminished during a judge's tenure of office." 575. The theory of the Supremacy of the Constitution is thus not a new one at all. It is inherent in the very concept of "the auguster thing" which lies behind Parliament or king and is sought to be embodied in the Constitution of a country. The Judges, who are vested with the authority and charged with the duty to uphold the Constitution, do so as the mouthpieces of what has been called the "Real will" of the people themselves by political philosophers such as Bosanquet. That, as I have indicated earlier, is the theory underlying