Separation of powers

Constitutional theory principally associated with French political theorist Charles-Louis de Secondat, Baron de Montesquieu (1689-1755).

Liberty and good government are secured by the powers of government being separated amongst distinct, autonomous, but co-ordinated institutions; usually executive, legislature, and judiciary.

David Miller et al., eds, The Blackwell Encyclopaedia of Political Thought (1987)


Aristotle first mentioned the idea of a “mixed government” or hybrid government in his work Politics, where he drew upon many of the constitutional forms in the city-states of Ancient Greece. In the Roman Republic, the Roman SenateConsuls and the Assemblies showed an example of a mixed government according to Polybius (Histories, Book 6, 11–13).Antiquity

Early modern mixed government

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.”[1] 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.[2]

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.[3][need quotation to verify] 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.[4] Massachusetts Bay Colony (founded 1628), Rhode Island (1636), Connecticut (1636), New Jersey, and Pennsylvania had similar constitutions – they all separated political powers. (Except for Plymouth Colony and Massachusetts Bay Colony, these English outposts added religious freedom to their democratic systems, an important step towards the development of human rights.[5][6]) Books like William Bradford’s Of Plymouth Plantation (written between 1630 and 1651) were widely read in England.[citation needed] So the form of government in the colonies was well known in the mother country, including to the philosopher John Locke (1632–1704). He 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. (The Kingdom of England had no written constitution.)[7][need quotation to verify][8]

Tripartite System

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.[9]

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).[10]

Montesquieu’s separation of powers system


The term “tripartite system” is commonly ascribed to French Enlightenment political philosopher Baron de Montesquieu, although he did not use such a term but referred to “distribution” of powers. In The Spirit of the Laws (1748),[11] 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.[12][13][14] In the British constitutional system, Montesquieu discerned a separation of powers among the monarch, Parliament, and the courts of law.[15]

In every government there are three sorts of power: the legislative; the executive in respect to things dependent on the law of nations; and the executive in regard to matters that depend on the civil law.

By virtue of the first, the prince or magistrate enacts temporary or perpetual laws, and amends or abrogates those that have been already enacted. By the second, he makes peace or war, sends or receives embassies, establishes the public security, and provides against invasions. By the third, he punishes criminals, or determines the disputes that arise between individuals. The latter we shall call the judiciary power, and the other simply the executive power of the state.

Montesquieu argues that each Power should only exercise its own functions. He was quite explicit here:[16]

When the legislative and executive powers are united in the same person, or in the same body of magistrates, there can be no liberty; because apprehensions may arise, lest the same monarch or senate should enact tyrannical laws, to execute them in a tyrannical manner.

Again, there is no liberty, if the judiciary power be not separated from the legislative and executive. Were it joined with the legislative, the life and liberty of the subject would be exposed to arbitrary control; for the judge would be then the legislator. Were it joined to the executive power, the judge might behave with violence and oppression.

There would be an end of everything, were the same man or the same body, whether of the nobles or of the people, to exercise those three powers, that of enacting laws, that of executing the public resolutions, and of trying the causes of individuals.

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.[17]

The executive power ought to be in the hands of a monarch, because this branch of government, having need of despatch, is better administered by one than by many: on the other hand, whatever depends on the legislative power is oftentimes better regulated by many than by a single person.

But if there were no monarch, and the executive power should be committed to a certain number of persons selected from the legislative body, there would be an end then of liberty; by reason the two powers would be united, as the same persons would sometimes possess, and would be always able to possess, a share in both.

Montesquieu actually specified that the independence of the judiciary has to be real, and not merely apparent.[18] The judiciary was generally seen as the most important of the three powers, independent and unchecked.[19]

Checks and balances[edit]

The principle of checks and balances is that each branch has power to limit or check the other two, which creates a balance between the three separate branches of the state. This principle induces one branch to prevent either of the other branches from becoming supreme, thereby securing political liberty.

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.[20] 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.[21] They guarantee that the branches have the same level of power (co-equal), that is, are balanced, so that they can limit each other, avoiding the abuse of power. The origin of checks and balances, like separation of powers itself, is specifically credited to Montesquieu in the Enlightenment (in The Spirit of the Laws, 1748). Under this influence it was implemented in 1787 in the Constitution of the United States.

The following example of the separation of powers and their mutual checks and balances from the experience of the United States Constitution is presented as illustrative of the general principles applied in similar forms of government as well:[22]

But the great security against a gradual concentration of the several powers in the same department, consists in giving to those who administer each department the necessary constitutional means and personal motives to resist encroachments of the others. The provision for defense must in this, as in all other cases, be made commensurate to the danger of attack. Ambition must be made to counteract ambition. The interest of the man must be connected with the constitutional rights of the place. It may be a reflection on human nature, that such devices should be necessary to control the abuses of government. But what is government itself, but the greatest of all reflections on human nature? If men were angels, no government would be necessary. If angels were to govern men, neither external nor internal controls on government would be necessary. In framing a government which is to be administered by men over men, the great difficulty lies in this: you must first enable the government to control the governed; and in the next place oblige it to control itself.

A dependence on the people is, no doubt, the primary control on the government; but experience has taught mankind the necessity of auxiliary precautions. This policy of supplying, by opposite and rival interests, the defect of better motives, might be traced through the whole system of human affairs, private as well as public. We see it particularly displayed in all the subordinate distributions of power, where the constant aim is to divide and arrange the several offices in such a manner as that each may be a check on the other that the private interest of every individual may be a sentinel over the public rights. These inventions of prudence cannot be less requisite in the distribution of the supreme powers of the State.

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