1.1 Background of the Study
The origin of this doctrine started from the work of the British philosopher John Locke who observed the conditions of the 17th century England. In his work, second Treatise on Civil Government, he reasoned that:
“It may be too great a temptation to human frailty, apt to grasp at power, for the same persons who have the power of making laws, to have also in their hands the power to execute them, whereby they may exempt themselves from obedience to the laws they made, and suit the law both in its making and execution, to their own private advantage” (italicized by researcher)
Power which is not checked may become absolute. This position agrees with the views of Ben Nwabueze:
“Concentration of government powers in the hands of one individual is the very definition of dictatorship and absolute power is by very nature arbitrary, capricious and despotic…” (italicized by researcher).
However, the applicability of this doctrine has been the subject of controversy in modern democracies across the world. This may be particularly due to the fact that there is no strict or watertight application of the doctrine of separation of powers. In actual practice, there is flexibility which logically leads to Principle of checks and balance. One branch or arm of government operates as a check on the other. James Madison , a Republican and Fourth President of the United States of America have this to say:
“In framing a government which is to administered by men, the great difficulty lies in this; you must first enable the government to control the governed, and the next place oblige it to control itself…”
Nigeria operates a democratic system of government. As obtainable in other similar jurisdictions, the concept of separation of power is an essential element of the Rule of Law and is enshrined in our Constitution.However, in practice, the doctrine operates in such ways that each arm of government acts independently of one another but also serves as a check and balance on one another to prevent the excess and abuse of power.
1.2 Statement of the Problem
There is need for a review and amendment of the Nigerian Constitution to reflect the practicability of the doctrine of separation of powers. This is because the applicability doctrine is an ever increasing controversy. The dynamics of the modern democracy has thrown up new constitutional challenges relating to the exercise of government powers.
Under the Constitutional arrangement, one branch of government should not encroach on the jurisdiction of another nor exercise the powers of another branch of government. The concentration of powers in the same person or body would lead to tyranny because based on the saying that power corrupts and absolute power corrupts absolutely, if the exercise of these powers do not have limits, there would be massive abuse of these powers.
 John Locke was an English philosopher and physician, widely regarded as one of the most influential of enlightenment thinkers and commonly known as the father of liberalism. He was among the most famous philosophers and political theorists between 1632 – 1704.
 John Locke, Second Treaties on Civil Government, chapter 12-13. Quoted in Wade Stewart & Philips Godfrey: Constitutional Administrative Law, 9thedn. London: Longman Publishers, (1977) at p.45.
 Ben Nwabueze: The Presidential Constitution of Nigeria, 1981, at p.32. Quoted in AbiolaOjo: Separation of Powers in a Presidential System of Government, London: Stevens & Sons Ltd., (1981)at p. 105.
Alexander H. et al; The Federal Harvard University Library, No.51. P. 356
 Constitution of the Federal Republic of Nigeria 1999 (as amended) Laws of the Federation 2004