Separation of Power means, judiciary, executive and legislature should work in their own field and should not interfere in one other’s works. The doctrine was propounded by French Political Philosopher Montesquieu in his book ‘Espirit des lois’ in 1748. The American constitution makers were so much influenced by this doctrine and they used it in American government. Later on, this was used by other constitutions including India. Indian constitution does not use the doctrine in its raw form, we have used with some modifications.
According to Montesquieu, “when the legislative and executive powers are united in the same person or body of persons there can be no liberty, because of the danger that the same monarch or senate should enact tyrannical laws and execute them in a tyrannical manner.”
William Blackstone in his ‘Commentaries on the laws of England’ (1756) expresses the same thought by saying that “wherever the right of making and enforcing the law is vested in the same man or one and the same body of men, there can be no public liberty”.
Harold Laski in his Liberty in the Modern State’ (1961) wrote, “… if in any state there is a body of men who possess unlimited political power, those over whom they rule can never be free. For the one assured result of historical investigation is the lesson that uncontrolled power is invariably poisonous to those who possess it. They are always tempted to impose their canon of good upon others, and, in the end, they assume that the good of the community depends upon the continuance of their power.
Liberty always demands a limitation of political authority, and it is never attained unless the rulers of a state can, where necessary, be called to account. That is why Pericles insisted that the secret of liberty is courage.”