Separation of powers

The separation of powers principle functionally differentiates several types of state power (usually law-making, adjudication, and execution) and requires these operations of government to be conceptually and institutionally distinguishable and articulated, thereby maintaining the integrity of each. To put this model into practice, government is divided into structurally independent branches to perform various functions (most often a legislature, a judiciary and an administration, sometimes known as the trias politica). When each function is allocated strictly to one branch, a government is described as having a high degree of separation; whereas, when one person or branch plays a significant part in the exercise of more than one function, this represents a fusion of powers.
Polybius (Histories, Book 6, 11–13) described the Roman Republic as a mixed government ruled by the Roman Senate, Consuls and the Assemblies). Polybius explained the system of checks and balances in detail, crediting Lycurgus of Sparta with the first government of this kind.
John Calvin (1509–1564) favoured a system of government that divided political power between democracy and aristocracy (mixed government). Calvin appreciated the advantages of democracy, stating: "It is an invaluable gift if God allows a people to elect its own government and magistrates." In order to reduce the danger of misuse of political power, Calvin suggested setting up several political institutions that should complement and control each other in a system of checks and balances. In this way, Calvin and his followers resisted political absolutism and furthered the growth of democracy. Calvin aimed to protect the rights and the well-being of ordinary people.
In 1620 a group of English separatist Congregationalists and Anglicans (later known as the Pilgrim Fathers) founded Plymouth Colony in North America. Enjoying self-rule, they established a bipartite democratic system of government. The "freemen" elected the General Court, which functioned as legislature and judiciary and which in turn elected a governor, who together with his seven "assistants" served in the functional role of providing executive power. Massachusetts Bay Colony (founded 1628), Rhode Island (1636), Connecticut (1636), New Jersey, and Pennsylvania had similar constitutions – they all separated political powers.
John Locke (1632–1704) deduced from a study of the English constitutional system the advantages of dividing political power into the legislative (which should be distributed among several bodies, for example, the House of Lords and the House of Commons), on the one hand, and the executive and federative power, responsible for the protection of the country and prerogative of the monarch, on the other hand, as the Kingdom of England had no written constitution.
During the English Civil War, the parliamentarians viewed the English system of government as composed of three branches – the King, the House of Lords, and the House of Commons – where the first should have executive powers only, and the latter two legislative powers. One of the first documents proposing a tripartite system of separation of powers was the Instrument of Government, written by the English general John Lambert in 1653, and soon adopted as the constitution of England for few years during The Protectorate. The system comprised a legislative branch (the Parliament) and two executive branches, the English Council of State and the Lord Protector, all being elected (though the Lord Protector was elected for life) and having checks upon each other.
A further development in English thought was the idea that the judicial powers should be separated from the executive branch. This followed the use of the juridical system by the Crown to prosecute opposition leaders following the Restoration, in the late years of Charles II and during the short reign of James II (namely, during the 1680s).
The first constitutional document to establish the principle of the separation of powers in government between the legislative, executive, and judiciary branches was Pacts and Constitutions of Rights and Freedoms of the Zaporizhian Host, written in 1710 by Ukrainian Hetman Pylyp Orlyk.
An earlier forerunner to Montesquieu's tripartite system was articulated by John Locke in his work Two Treatises of Government (1690). In the Two Treatises, Locke distinguished between legislative, executive, and federative power. Locke defined legislative power as having "the right to direct how the force of the commonwealth shall be employed" (Second Treatise, § 143), while executive power entailed the "execution of the laws that are made, and remain in force" (Second Treatise, § 144). Locke further distinguished federative power, which entailed "the power of war and peace, leagues and alliances, and all transactions with all persons and communities without [outside] the commonwealth" (Second Treatise, § 145), or what is now known as foreign policy. Locke distinguishes between separate powers but not discretely separate institutions, and notes that one body or person can share in two or more of the powers. Within these factors Locke heavily argues for "Autry for Action" as the scope and intensity of these campaigns are extremely limited in their ability to form concentrations of power. For instance, Locke noted that while the executive and federative powers are different, they are often combined in a single institution (Second Treatise, § 148).
Locke believed that the legislative power was supreme over the executive and federative powers, which are subordinate. Locke reasoned that the legislative was supreme because it has law-giving authority; "[F]or what can give laws to another, must need to be superior to him" (Second Treatise, § 150). According to Locke, legislative power derives its authority from the people, who have the right to make and unmake the legislature. He argues that once people consent to be governed by laws, only those representatives they have chosen can create laws on their behalf, and they are bound solely by laws enacted by these representatives.
Locke maintained that there are restrictions on the legislative power. Locke says that the legislature cannot govern arbitrarily, cannot levy taxes, or confiscate property without the consent of the governed (cf. "No taxation without representation"), and cannot transfer its law-making powers to another body, known as the nondelegation doctrine (Second Treatise, § 142).
The term "tripartite system" is commonly ascribed to French Enlightenment political philosopher Montesquieu, although he did not use such a term but referred to the "distribution" of powers. In The Spirit of Law (1748), Montesquieu described the various forms of distribution of political power among a legislature, an executive, and a judiciary. Montesquieu's approach was to present and defend a form of government whose powers were not excessively centralized in a single monarch or similar ruler (a form known then as "aristocracy"). He based this model on the Constitution of the Roman Republic and the British constitutional system. Montesquieu took the view that the Roman Republic had powers separated so that no one could usurp complete power. In the British constitutional system, Montesquieu discerned a separation of powers among the monarch, Parliament, and the courts of law.
Montesquieu argues that each Power should only exercise its functions. He was quite explicit here:
Separation of powers requires a different source of legitimization, or a different act of legitimization from the same source, for each of the separate powers. If the legislative branch appoints the executive and judicial powers, as Montesquieu indicated, there will be no separation or division of its powers, since the power to appoint carries with it the power to revoke.
Montesquieu actually specified that the judicial independence has to be real, and not merely apparent. The judiciary was generally seen as the most important of the three powers, independent and unchecked.
According to the principle of checks and balances, each of the branches of the state should have the power to limit or check the other two, creating a balance between the three separate powers of the state. Each branch's efforts to prevent either of the other branches from becoming supreme form part of an eternal conflict, which leaves the people free from government abuses. Immanuel Kant was an advocate of this, noting that "the problem of setting up a state can be solved even by a nation of devils" so long as they possess an appropriate constitution to pit opposing factions against each other. Checks and balances are designed to maintain the system of separation of powers keeping each branch in its place. The idea is that it is not enough to separate the powers and guarantee their independence but the branches need to have the constitutional means to defend their own legitimate powers from the encroachments of the other branches. Under this influence it was implemented in 1787 in the Constitution of the United States separation of powers. In Federalist No. 78, Alexander Hamilton, citing Montesquieu, redefined the judiciary as a separately distinct branch of government with the legislative and the executive branches. Before Hamilton, many colonists in the American colonies had adhered to British political ideas and conceived of government as divided into executive and legislative branches (with judges operating as appendages of the executive branch).
James Madison wrote about checks (and balances) in Federalist No. 51:
Thomas Paine wrote about balances in Common Sense:
Importantly, Thomas Paine rejected the theory that English liberty was secured by constitutionally guaranteed checks and balances. Denouncing the whole notion of checks and balances, at least as far as the English constitution was concerned, Paine articulated the case for republican virtue as follows:
There are different theories about how to differentiate the functions of the state (or types of government power), so that they may be distributed among multiple structures of government (usually called branches of government, or arms). There are analytical theories that provide a conceptual lens through which to understand the separation of powers as realized in real-world governments (developed by the academic discipline of comparative government); there are also normative theories, both of political philosophy and constitutional law, meant to propose a reasoned (not conventional or arbitrary) way to separate powers. Disagreement arises between various normative theories in particular about what is the (desirable, in the case of political philosophy, or prescribed, in the case of legal studies) allocation of functions to specific governing bodies or branches of government. How to correctly or usefully delineate and define the 'state functions' is another major bone of contention.
The legislative function of the government broadly consists of authoritatively issuing binding rules.
The function of adjudication (judicial function) is the binding application of legal rules to a particular case, which usually involves creatively interpreting and developing these rules.
The executive function of government includes many exercises of powers in fact, whether in carrying into effect legal decisions or affecting the real world on its own initiative.
Adjudicating constitutional disputes is sometimes conceptually distinguished from other types of power, because applying the often unusually indeterminate provisions of constitutions tends to call for exceptional methods to come to reasoned decisions. Administration is sometimes proposed as a hybrid function, combining aspects of the three other functions; opponents of this view conceive of the actions of administrative agencies as consisting of the three established functions being exercised next to each other merely in fact. Supervision and integrity-assuring activities (e.g., supervision of elections), as well as mediating functions (pouvoir neutre), are also in some instances regarded as their type, rather than a subset or combination of other types. For instance, Sweden has four powers, judicial, executive, legislative, and administrative branches.
One example of a country with more than 3 branches is Taiwan, which uses a five-branch system. This system consists of the Executive Yuan, Legislative Yuan, Judicial Yuan, Control Yuan, and Examination Yuan.