The doctrine of separation of powers as it is known today developed from the writings of classical and medieval thinkers such as Aristotle who opined that:

There are three elements in each constitution in respect of which every serious lawgiver must look for what is advantageous to it; if these are well arranged, the constitution is bound to correspond to the differences between each of these elements. These are, first, the deliberative, which discusses everything of common importance; second, the officials; and third, the judicial element[1]. (SEPARATION OF POWERS)

According to Madison, “where the whole power of one department is exercised by the same hands which possess the whole power of another department, the fundamental principles of a free constitution are subverted[2].” (SEPARATION OF POWERS)




The doctrine of separation of powers is a fundamental component of most modern democratic political systems. The doctrine presupposes an arrangement whereby the political powers which exist in any form of government should not be consolidated or concentrated in one person or group of persons. What is meant by this is that the existing powers must be separated into different organs and whatever power is vested in any organ should not be encroached upon by another organ[3]? The premise behind the separation of powers is that when a single person or group has a large amount of power, they can become dangerous to citizens. The doctrine, therefore, holds that liberty is best preserved if the tripartite functions of government- legislation, law enforcement, and adjudication are in different hands. It is generally accepted that there are three main categories of governmental functions- the Legislative, Executive and Judicial. According to the doctrine, these three powers and functions of government must, in a free democracy, always be kept separate and exercised by separate organs of government. The legislature cannot, therefore, exercise executive or judicial power; the executive cannot exercise the legislative or judicial power of the government[4]. (SEPARATION OF POWERS)

The concept of ‘separation of powers’ explained by Wade and Philips[5], means three different things:

  1. That the same persons should not form part of more than one of the three organs of Government, e.g. the Ministers should not sit in Parliaments;
  2. That one organ of the Government should not control or interfere with the exercise of its function by another organ, e.g. the Judiciary should be independent of the Executive or that Ministers should not be responsible to Parliament; and
  • That one organ of the Government should not exercise the functions of another, e.g. the Ministers should not have legislative powers.
  1. Thus, the whole purpose of the doctrine is to avoid tyranny in government. There is no gainsaying the fact that a government of separated powers is likely not to be tyrannical and more likely to follow the rule of law. However, it must be pointed out from the onset that there is no rigid application of the doctrine of separation of powers in the constitutional framework of any democratic State. The main object as per Montesquieu- is that there should be a government of law rather than having willed and whims of the official. It is to this end that the three branches of government usually have some overlap in their constitutionally assigned functions. As observed by Justice Oluwadare Aguda[6], there is no way in which all the powers of the State and functions of government can be shared out and put into mutually exclusive compartments and assigned to different segments of government. Some overlapping is bound to occur and occurs at various times. He noted further that, while much of the overlapping of powers between the different arms of government may not be intended by the Constitution, yet the most important of such overlapping arises from the powers allowed by the Constitution itself. (SEPARATION OF POWERS)

[1] Op. cit fn 13


[2] Federalist No. 47 (1788)

[3] D.O Odeleye and Mohammed Etudaye, “The Theory and Practice of Separation of Powers in a Presidential Constitution- The Nigerian Experience”. Abuja Journal of Public and International Law (2010)1:1, P.297

[4] C.K Takwani, Lectures on Administrative Law (India: Eastern Book Company, 2008) P. 31

[5] Constitutional Law (1960) P. 22

[6] Oluwadare A., Understanding the Nigerian Constitution of 1999 ( Lagos: MIJ Professional Publishers) 2000

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