Sovereignty is supreme authority. It involves authority over all others within its field of operation, and the absence of any other superior authority in that same field. It is essentially a legal construct, rather than one reflecting the possession of power and authority in practice (sometimes referred to as political sovereignty).
Sovereignty is a concept used predominantly in the domestic context of the legal authority wielded within and by a State. It is thus more a concept of constitutional law than of international law, since on the international plane no State has as a matter of law authority over all other States.
The notion of sovereignty as it is now understood only entered the vocabulary of political discourse in the second half of the 16th century, at a time when modern conceptions of the State were beginning to take shape. Before then notions of supreme authority in the community as a whole were based more on religious than temporal considerations. But even in the middle ages the word souverain (itself derived from the Latin superanus, meaning “above”) was used to denote an authority, political or other, which within its particular hierarchy had no authority above itself (such as a cour souveraine, which was a court with no superior court above it). As States in Western Europe evolved in the 16th century and subsequently, the need grew for the State’s authority to have a firm temporal basis. In parallel there also developed a need for rulers of these evolving States to confirm their authority within their States to the maximum extent possible.
It was against this background that the term “sovereignty” was introduced into political science by Bodin in De la République (1577). Building on older notions of what was souverain, the concept was introduced and developed in political theory in the context of the power of the ruler of the State over everything within the State. Bodin, writing in support of centralised State absolutism, defined sovereignty as the absolute and perpetual power within a State: sovereignty was the attribute of a king in a monarchy and of the people in a republic. For Bodin such power was the supreme power within the State without any restriction other than the Commandments of God and the Law of Nature. That supreme power could not be limited by any Constitution or by positive law. Hobbes, in De Cive (1642), went further than Bodin in maintaining that a sovereign was not bound by anything; others (such as Pufendorf, in De Jure Naturae et Gentium (1672)) took a more restrictive view, acknowledging that while sovereignty was the supreme power within a State it was not an absolute power, and could be constitutionally restricted. But virtually all agreed that sovereignty was indivisible - either a State and its ruler was sovereign, or it was not.
The disintegration of the German Empire in the eighteenth century saw the emergence into the international community of several hundred reigning princes of the Empire’s former member States. After the Westphalian Peace of 1648 these States and their rulers enjoyed in practice even if not in theory a large degree of independence. Yet it was not felt appropriate to treat them as sovereign States of the same standing as the major European States such as France, Sweden and England. Instead, full sovereignty was attributed to all rulers who held supreme authority within their States and enjoyed unqualified independence in their relations with other rulers. Such “sovereign rulers” ranked equally as amongst their fellow-sovereign rulers, but above those other rulers who in some way did not have supreme authority within their States or unqualified external independence but were to some degree in law dependent upon the authority of some other ruler.
While Kings and Emperors were accordingly acknowledged to be of the highest rank in terms of their sovereign authority, the standing of the many lesser rulers, such as Princes of varying status, Grand Dukes, and so on, was characterised by their enjoyment of only relative, partial or imperfect sovereignty. At a time when a ruler could properly say “L’État, c’est moi”, such considerations of comparative ranking were not just a matter of personal aggrandisement but touched on issues of high politics in the emerging international community.
These developments confirmed what had been apparent since its origins in the sixteenth century, namely that “sovereignty” was perceived primarily in terms of internal constitutional power and authority, conceived as the highest, temporally underived power within the State with exclusive competence therein. They also established that, contrary to earlier views and despite some continuing theoretical objections (e.g. by Rousseau, Contrat Social (1762)), sovereignty was in practice potentially divisible - a practice confirmed in particular by the transformation of the United States in 1787 from a confederation of States into a federal State, in which the State’s overall sovereignty was shared between the central Federal State and the several member States.
In the essentially religious societies in which the evolution of modern statal communities was taking place, no temporal ruler could assert his supreme authority within the State without at the same time recognising the overriding spiritual authority of whatever God or God-like Being the community acknowledged. The constitutional structures of the different States developed different ways of accommodating this need to combine spiritual and temporal authority - thus in some the ruler himself possessed divine status, in others the ruler was regarded as divinely chosen and appointed, in others divinity was seen to be reflected in natural law by which the ruler was bound notwithstanding his temporal sovereignty. Whatever the technique, however, it was essentially one devised by the constitutional developments within the State concerned.
At the beginning of the 21st century the continued theoretical utility of the concept of sovereignty is increasingly open to question. As a concept denoting supreme legal authority it never was appropriate for the international position of States, since no State has such authority over all other States. In its proper field of internal constitutional law, the growing interdependence of States has both reduced the areas in which a State may truly be said to exercise supreme legal authority within its own borders, and has increased the areas in which authority within a State’s territory may lawfully be exercised by some other State or other external authority. Quite apart from such emerging developments in the scope of States’ legal power and authority, the practical realities of international life make it no longer appropriate for a State to determine its sovereign status by looking only to its internal legal position: the legal powers and freedom of action of all States is restrained by their interreactions with other States and international authorities.
Politically, however, “sovereignty” has lost none of its appeal, much of it at bottom nationalistic and emotional. Such political use of notions of sovereignty is nowadays little more than a nostalgic attempt to invoke the memory of past freedoms, independence and supremacy.
(1) Sovereignty and international law: independence and equality. Within the overall context of self-determination the place of sovereignty in international law requires some explanation, since self-determination is usually (although erroneously) seen as a quest for sovereignty and independence.
Sovereignty as a principle of international law is to be distinguished sharply from sovereignty in its internal and constitutional aspects. It is implicit in the nature of sovereignty as supreme authority that such a notion of sovereignty is inapplicable to the role of sovereign States on the international plane and within international law. Internationally, no State has supreme legal power and authority over other States in general, nor are States generally subservient to the legal power and authority of other States (although in former times such claims were occasionally made, most notably in the traditional Chinese view of international relations, maintained for well over a millenium, that the rightful relationship of all foreigners with the imperial court was one of respectful subordination - a view which led to major differences on the occasion of the visit of a British diplomatic and trade mission to the Chinese Emperor, Qianlong, in 1793). Moreover, State sovereignty on the international plane would be inconsistent with the conception of international law as a body of rules of conduct binding upon States irrespective of their internal domestic law, for this implies their subjection to international law and renders untenable any claims by a State on the international plane to absolute sovereignty and to the lawfulness of its conduct being beyond question.
Sovereignty is also not to be confused with international personality. The former is based on notions of supreme authority and independence. International personality connotes the possession of rights, duties, powers and capacities in international law: whatever person or entity possesses rights, duties, powers and capacities in international law has international personality, even if that person or entity does not possess sovereignty. Sovereign States characteristically possess the full range of international legal rights, duties, powers and capacities, and undoubtedly possess international personality. But many States which are in one way or another subject to the authority of another State and may well therefore not be fully sovereign, may nevertheless, through the possession of at least some of the legal entitlements conferred by international law, enjoy international personality (albeit on a less plenary basis that do sovereign States); the same applies to non-statal entities such as many international organisations.
Sovereignty being supreme authority necessarily implies independence. “Toute nation qui se gouverne elle-même, sous quelque forme que ce soit, sans dépendance d’aucun étranger, est un État souverain” (Vattel, Le droit des gens (1773 ed.), Bk. 1, Ch. 1, s.4). A ruler or State which is sovereign is, strictly, independent of any other temporal legal authority so far as concerns its legal powers within its borders, and is equally independent as regards its legal authority to act beyond its borders. A sovereign ruler’s domestic legal authority to act both internally and externally is not in law dependent on any other earthly authority. In modern times independence (despite difficulties of application which can arise in practice) has come to be regarded as the essential quality of ‘sovereign’ States, and on the international plane as in effect coterminous with sovereignty and as the defining characteristic of Statehood.
Independence was referred to in classic terms by Judge Anzilotti in 1931 as involving
“the existence of [a State], within its frontiers ..., as a separate State and not subject to the authority of any other State or group of States. Independence as thus understood is really no more than the normal condition of States according to international law; it may also be described as sovereignty (supreme potestas), or external sovereignty, by which is meant that the State has over it no other authority than that of international law ... As long as these restrictions [i.e. upon a State’s liberty and arising out of ordinary international law or contractual engagements] do not place the State under the legal authority of another State, the former remains an independent State however extensive and burdensome those obligations may be.”
In the perspective of international law sovereignty has always predominantly been, and is now invariably, seen as a legal construct of the domestic constitutional law of States, of which international law takes cognisance as a fact but which is not itself based on international law. Instead of supreme authority over all other States, sovereignty, in international law, brings into play considerations of comparative ranking similar to those which influenced the development of conceptions of sovereignty within the framework of domestic political theory. If ruler A is, in his domestic legal order, a sovereign ruler, then he is, in terms of legal standing, in the same position as ruler B who, in his domestic legal order, is also a sovereign ruler. As between two rulers (and thus their States) who are both (internally) sovereign, the appropriate legal relationship is one of equality. The sovereignty of their States is not sovereignty as a matter of international law, but rather a sovereignty in their separate domestic laws of which international law takes due note. In international law sovereignty is more descriptive of the authority of a State and its ruler within and as a matter of domestic law than constitutive of their authority as a matter of international law: it is more an attribute of Statehood in international law, than a condition for its existence.
Since the gradations of authority which formerly characterised the constitutional position of statal communities are now largely a thing of the past, and virtually all such communities have now become fully sovereign States, it is in the sense just described that one of the legal constitutional underpinnings of modern international law is the sovereign equality of States: “The [United Nations] Organization is based on the principle of the sovereign equality of all its Members” (UN Charter, Article 2.1). This principle was elaborated in the 1970 Declaration on Principles of International Law (GA Res 2625(XXV)(1970)) in the following terms:
All States enjoy sovereign equality. They have equal rights and duties and are equal members of the international community, notwithstanding differences of an economic, social, political or other nature.
In particular, sovereign equality includes the following elements:
(a) States are juridically equal;
(b) Each state enjoys the rights inherent in full sovereignty;
(c) Each state has the duty to respect the personality of other states;
(d) The territorial integrity and political independence of the state are inviolable;
(e) Each state has the right freely to choose and develop its political, social, economic and cultural systems;
(f) Each state has the duty to comply fully and in good faith with its international obligations and to live in peace with other states.”
A State may, without thereby losing its quality as a sovereign State, limit the exercise of its sovereign rights by concluding a treaty to that effect with one or more other States. Treaties of that kind are a commonplace of international relations. Traditionally the right to conclude treaties is seen as an attribute of a State’s sovereignty rather than as a negation of it. There comes, however, a point at which a State in undertaking limitations upon the exercise of its sovereign rights may be considered to have subordinated its will to that of another State and thereby to have lost its independence: in such circumstances the State’s very sovereignty will be seen to have been prejudiced.
(2) Territorial sovereignty. Fundamental to the sovereignty of a State is not only its (internally) supreme authority, and thus its independence from and equality with other similarly sovereign States, but also the spatial extent within which its supreme authority is exercised: its sovereignty is recognised within and delimited by its territory. By virtue of its sovereignty over its internal affairs, it is inherent in the domestic law concept of sovereignty that in principle a State has exclusive authority and jurisdiction within its own territory (and that other States are under a duty of non-intervention in areas subject to its exclusive jurisdiction); in particular all States are acknowledged to have sovereignty over their natural resources.
That territorial exclusivity is also acknowledged to be a central characteristic of a sovereign State as a matter of international law, reflected in another of the of the basic principles of the United Nations Charter - the prohibition of “the threat or use of force against the territorial integrity or political independence of any state” (Article 2.4). Both of these notions - independence and territory - are part of the essential sovereignty of the State, and are cornerstones of international society and modern international law.
The essentials of what is meant by territorial sovereignty in contemporary international law were identified by Judge Huber in his classic statement in his arbitral award in the Island of Palmas Case (1928), where he said:
“Sovereignty in relation to a portion of the surface of the globe is the legal condition necessary for the inclusion of such portion in the territory of any particular State... Sovereignty in the relations between States signifies independence. Independence in regard to a portion of the globe is the right to exercise therein, to the exclusion of any other State, the functions of a State. The development of the national organization of States during the last few centuries and, as a corollary, the development of international law, have established this principle of the exclusive competence of the State in regard to its own territory in such a way as to make it the point of departure in settling most questions that concern international relations ... Territorial sovereignty belongs always to one, or in exceptional circumstances several States, to the exclusion of all others....”.
There is, it must be noted, an inherent tension between a State’s fundamental right to territorial sovereignty, and the exercise by part of that State of a right of self-determination. That tension is recognised by such provisions as that “Nothing in the foregoing paragraphs shall be construed as authorizing or encouraging any action which would dismember or impair, totally or in part, the territorial integrity or political unity of sovereign and independent States ....” Recognition of the tension is, however, one thing: its resolution is quite another.
(3) Sovereign rights. Whereas sovereignty is seen as a comprehensive collection of international rights, duties, powers and capacities, in some circumstances and in respect of certain geographical areas that full range - and thus sovereignty as such - has been found to be inappropriate, and instead only some of those elements of sovereignty are acknowledged to be possessed by the State concerned. This device of ‘sovereign rights’ has in particular been adopted in the context of the areas of continental shelf and exclusive economic zone appertaining to a State, in relation to which areas the State does not have full sovereignty but only sovereign rights for certain specific purposes (UN Convention on the Law of the Sea 1982, Arts. 56, 77).
(4) Sovereignty and self-determination. Against the background of these fundamental principles of sovereignty (as independence and equality in relation to a given territory) and sovereign rights, the operation of principles of self-determination has developed a number of distinctive features which illustrate the flexibility of modern applications of the underlying concept of sovereignty.
(a) Colonies. Normally a State’s territory is a relatively homogenous area ruled from a central seat of authority. Formerly this territory comprised the areas around the ruler’s seat which, by virtue of the network of personal allegiances which characterised feudal polities, were directly or indirectly subject to the ruler’s authority. As the feudal system decayed and was increasingly replaced by the direct imposition of authority upon outlying regions by central organs of authority, so the territorial limits of that central authority were seen as the boundaries of the single political unit constituted by the State.
A State’s sovereignty was not, however, necessarily limited to the area immediately surrounding the central seat of authority. In various ways a State, or formerly its ruler personally, could acquire territories which might well not be adjacent to the State’s ‘core’ territory. Thus additional territory might, for example, be acquired by conquest, or by purchase, or by occupation, or by cession, or (particularly in former times) through marriage. Contemporary examples of States with geographically separated components include (apart from the somewhat special case of those States composed of groups of islands, like the Philippines, and Indonesia) the USA (of which Alaska and Hawaii are constituent States), and Germany (of which East Prussia is a constituent part). In many cases the territory brought under the sovereignty of the State may be situated at a distance from the State’s ‘core’ or ‘homeland’ territory, sometimes thousands of miles away and on a quite different continent. Despite such distances, all these territories still fell within the State’s sovereignty, and were subject to the State’s exclusive rights to exercise its supreme authority. They came to be seen as generally having three major characteristics - they were geographically located ‘overseas’ from the parent, metropolitan sovereign State; their indigenous population was racially and ethnically distinct from that of the parent State; and their territories were settled by people from the parent State. From the Latin word colonus meaning a settlement, these territories came to be known as colonies.
Even such apparently straightforward extensions of territorial sovereignty to embrace overseas colonies have been accompanied by complicating features. Thus some States, such as France, have determined that some of their overseas territories constitute not separate colonies but rather départments (départments d’outre mer) alongside other such political units forming part of the internal constitutional structure of the State.
(b) Divided and limited sovereignty. The concept of divided sovereignty (whereby two States hold ‘supreme authority’ in respect of the same territory) and the notion that sovereignty may only be partial or limited have given rise to severe theoretical objections. Despite these, however, sovereignty over particular areas has in practice been shared between two other States, or has been possessed to only a limited extent (as with the notion of ‘sovereign rights’). The clearest example is perhaps to be found with condominia where two States jointly share sovereignty over some other territory, as with the Anglo-Egyptian Sudan from 1898-1955 and the Anglo-French island of New Hebrides from 1914 until its independence (as Vanuatu) in 1980. Another example of a kind of shared sovereignty, although this time shared temporally, occurs where a State leases part of its territory to a foreign State for a set period of years, leaving the territory still nominally part of the territory of the lessor State although it is generally unable to exercise the rights and duties of sovereignty during the continuance of the lease. Well-known examples of such leases were the leases executed in 1898 by China of the district of Kiaochow to Germany, Wei-Hai-Wei and the land opposite the island of Hong Kong to the United Kingdom, Kuang-Chou Wan to France, and Port Arthur to Russia; similarly, by Article 4 of the Peace Treaty of 1947 Finland granted the Soviet Union a 50 year lease in the area of Porkkala-Udd. The grant by Panama in 1903 of the use, occupation and control to the USA, to the exclusion of the exercise of any sovereign rights by Panama, of a 10 mile wide strip of land on which to construct, operate and defend the Panama Canal can be seen in a similar light: although the original grant was in perpetuity, the sovereignty of Panama over the totality of Panamanian territory was recognised in 1977. A further example of divided sovereignty to be noted is that which occurs within a federal State, where sovereignty within the (internationally) single federal State is shared between that State and its (internally) separate member States: the basis on which the State’s sovereignty is divided between the federal State and the member States depends upon the constitutional arrangements on the basis of which the federation was created, and varies from case to case.
(c) States under protection. A State may, however, exercise authority and control in or in respect of foreign territory without having sovereignty over it. While the expansion of empires and of international trade reinforced the need for States to acquire a degree of authority and control over outlying territories, they were able to do so sufficiently for their trading and political purposes (particularly preventing rivals from extending their competing authority and influence, and ensuring the security of trading routes) without having to undertake the political burdens, or the trouble and administrative expense, involved in formally bringing those territories under their sovereign authority. The eighteenth and nineteenth centuries in particular saw what was in some ways a partial return to the older system in which fully sovereign States co-existed with other States which, while still possessing a degree of statehood, were nevertheless not fully sovereign.
Various institutional devices were adopted to achieve this end, involving the establishment, as between the sovereign State and the less-than-sovereign State, of relationships characterized by labels such as “protected State” and “protectorate”. Usually the former label was applied to a protected entity which enjoyed separate statehood and which, while under protection, continues its status as a separate State but subject to (sometimes extensive) restraints upon its internal and/or external independence; the latter label on the other hand was applied to a protected entity which at no time had separate statehood (such as tribal entities) but which nevertheless placed itself by agreement under the protection of the protecting State - and as such these ‘protectorate’ arrangements were primarily a concern of the protecting State’s constitutional law rather than of international law. But these different labels were neither uniformly applied nor did they refer to formally distinct categories. To add to the confusion, those categories often had different connotations within the domestic constitutional law of the States concerned from those which they had as a matter of international law.
In that latter context the overriding characteristics of true ‘protected States’ were that they retained some (and often considerable) separate international identity and authority, that the relationship of protection was established by treaty with the protecting State, that the protecting State possessed at least the internationally significant rights associated with the defence of the territory and the conduct of its foreign relations so that, in effect, the international face of the protected State was that of the protecting State, and that generally speaking, the element of settlement by people from the parent State, which was characteristic of colonies, was absent in relation to these protected States. Crucially, they were not subject to the sovereignty of the protecting State, although clearly internationally dependent on it. They were sometimes, particularly later in their development, referred to somewhat euphemistically as ‘States in treaty relations’ with the protecting State.
Other forms by which dominant States exercised authority in relation to other territories have been devised from time to time, reflecting the needs of particular situations. Thus in some cases it became appropriate for a State to assume rights of ‘suzerainty’ over another State or territory; in others there has been developed a relationship of ‘association’ (under various names), the incidents of which vary with the circumstances but which generally involve a territory being internally self-governing but with another State being responsible for matters of defence and foreign affairs (e.g. the ‘Commonwealth’ relationship between the USA and Puerto Rico; the ‘free association’ between New Zealand and the Cook Islands; and the ‘Associated States’ established by the UK in the Caribbean in 1967). In some situations it has proved only necessary for a State to establish its authority and control in part of the territory of another State (usually a port or otherwise commercially significant area), such as the ‘capitulations’ which were established by certain Western States in certain other States, particularly in the Far East and Near East.
(d) Territories under internationally-based administration. The steady, but as yet still very limited, development of international institutions for the governance of the international community has seen the emergence of other, more internationally based, forms of the exercise of authority by a State over a usually distant and overseas territory, with somewhat uncertain consequences in the context of sovereignty. Foremost among these developments have been the mandate and trusteeship systems created under, respectively, the Covenant of the League of Nations and the Charter of the United Nations. The territories placed under a mandate, or a trusteeship agreement, were territories which formerly belonged to States defeated in the First and Second World Wars but which were taken from those States and placed under the temporary authority of particular mandatory States, or administering States in the case of trust territories, pending their attainment of independence. While it was clear that the States which formerly had sovereignty over those territories no longer did so, it was controversial to what extent the mandatory or administering States acquired sovereignty over them (even temporarily) and, if they did not do so, wherein sovereignty over them lay.
More recently a practice has begun to develop, usually in circumstances of considerable political disruption in a territory, whereby authority over a territorial unit is exercised directly by or under the authority of the United Nations typically for only a relatively short period of time and pending the establishment of more usual political structures for the territory. Examples of such a practice can be seen in the UN’s role in South West Africa (Namibia) (GA Res. 2145(XXI)(1966)), Cambodia (UN Transitional Authority in Cambodia: Paris Peace Agreement 1991, Art. 6, Annex 1), Kosovo (UN interim civil administration in Kosovo: SC Res. 1244(1999), and in East Timor (UN Transitional Administration in East Timor: SC Res. 1272(1999)). While such forms of international administration of territory are now an accepted feature of the international community, they do give rise to controversial questions of sovereignty.
While the exercise of particular and limited sovereign rights in such contexts is probably now an accepted part of the international framework, and while States are bound by and subject to the general body of international law, it cannot yet be said that the international community is so organised as to be in a position to assume general powers of sovereignty over the member States of that community. Nevertheless international organisations are now accepted as having international personality - that is, as having rights and duties in international law in their own right and separately from those vested in the member States - and in some instances (most notably in the case of the European Union) the development of the legal relationship between organisations and their member States has led to much debate as to whether that relationship may in future involve the acquisition of some degree of sovereignty on the part of the organisation and its loss by the member States (although the international statehood of the member States is not yet in question).
 Austro-German Customs Union Case, PCIJ, Ser. A/B No. 41 (1931), pp. 57-58.
 Friendly Relations Declaration, GA Res. 2625 (XXV)(1970), penultimate paragraph of the enunciation of the Principle of equal rights and self-determination of peoples. Although the continuation of the paragraph contains important qualifications, the nature of the inherent tension between territorial integrity and self-determination remains apparent.