5. The doctrine of separation of powers The doctrine of separation of powers has evolved since the writings of Locke and Montesquieu as various definitions have been coined. The concept of separation of powers divides the institutions of government into three branches: legislative, executive and judiciary where the legislature makes the laws; the executive put the laws into operation; while the judiciary interprets the laws. Separation of powers promotes democratic and good governance by ensuring that power is not concentrated in one state institution or one individual. Through mechanisms of checks and balances, the doctrine counters abuse of authority and promotes public accountability and transparency in the exercise of authority by each of the three branches of government. The doctrine of separation powers ought to be built into the fabric of all good modern constitutions2 . Separation of powers is both substantive and formal in nature. Substantively, it requires separation of mandate, personnel and the independence of each of these branches in the discharge of their authority. Formally, separation of powers requires the institutional division of governmental authority into the three branches. It is therefore necessary that a constitution capture both the formal and substantive features in order to effectively promote separation of powers. Institutional division of state governance into the three branches-executive, judiciary and legislature Separation of power (also known as trias politica principle) is a model of state governance where the state is divided into three branches namely the executive, the judiciary and the legislature. The executive comprises of the presidency and the cabinet, mandated with the authority to implement legislation. The legislature comprises of the parliament, mandated to enact laws while the judiciary comprises of the courts, mandated to administer the law. In order to capture and promote the idea of separation of powers, a constitution must clearly show this institutional division of governmental authority into these three branches. Guaranteed independence of each of the braches from the influence of each other The doctrine of separation of powers requires that these three branches be independent of each other and that they provide oversight of each other. In order to ensure the independence of each of these branches of government, the doctrine of separation of powers requires that no same person(s) should function as a member of more than one branch. Although for purposes of coordination of government functions, it becomes necessary that certain individuals operate in more than one branch of government. For instance, a cabinet minister (who is a member of the executive) can double up as a member of the legislature with the mandate to make regulations (known as subordinate legislation) that give flesh to principal legislation enacted by parliament. However, there ought to be mechanisms to ensure that such mandate is not abused. Checks and balances The doctrine of separation of powers also requires that the three branches of government must check against each other, to avoid abuse of authority. Therefore, the constitution must create mechanisms 2 Greg Linington; 2012, “Reflections on the significance of constitutions and constitutionalism for Zimbabwe”, page 63 in “Zimbabwe Mired in Transition” 25