This doctrine originated under the US constitution, like the theory of separation of power its objective is also to secure the liberty of the people and limit the authority of the government. Its inclusion in the constitution is an acknowledgement of the fact that it is not desirable to have a clear severance of the three wings of the government.
IF an organ of the government is left to itself completely and without any control it might misuse its power and become tyrannical and oppressive . The constitution therefore provides for a system of internal check and balances.
Under this doctrine, power of one organ of government are so devised as to exercise a check upon the power of the other organs of the government. This doctrine has been designed to promote overall equilibrium in the governance of the country.