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Max Planck Encyclopedia of Public International Law [MPEPIL]

Territory, Acquisition

Marcelo G Kohen, Mamadou Hébié

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved.date: 13 November 2019

Foreign relations law — Secession — Sovereignty — Territory, acquisition and transfer — Territory, title — Territory, non-self-governing

Published under the auspices of the Max Planck Foundation for International Peace and the Rule of Law under the direction of Rüdiger Wolfrum.

A.  A Note on Terminology

1.  Property, Ownership, and Acquisition of Territory: Clarification of Concepts

The expression ‘acquisition of territory’ is usually employed as meaning the establishment of sovereignty over a given piece of land. Well-known UN Security Council resolutions refer to ‘acquisition of territory’ in this manner, notably Resolution 242 (1967). The expression, however, requires some precision. First, strictly speaking, ‘territory’ as a term of art comprises not only emerged land, but also airspace, the territorial sea, and internal waters. However, what is essentially at issue in the ‘acquisition of territory’ is the acquisition of (emerged) land, with the rest of the above-mentioned components of the legal notion of ‘territory’ being land appurtenances. Second, States acquire, or establish through certain acts and conduct, a particular territorial status or particular rights rather than ‘territory’ per se. As will be examined below, different legal statuses apply to territory including sovereignty, which is undoubtedly the most important and common, albeit not the only possible legal status.

In the Sovereignty over Pedra Branca/Pulau Batu Puteh, Middle Rocks and South Ledge Case (Malaysia/Singapore) (Judgment), the International Court of Justice (‘ICJ’) noted that the term ‘ownership’ is sometimes used to refer to sovereignty (at para. 222). Indeed in State practice, expressions such as ‘acquisition of ownership over a territory’, ‘to possess the property of a territory’, or ‘to have dominium over a territory’ are often considered synonymous to ‘acquisition of territorial sovereignty’. Despite this confusing practice, a clear distinction must be maintained between the acquisition of private rights over a given territory and the acquisition of sovereignty over that territory. A decision concerning sovereignty over a given territory does not prejudice the ownership rights that individuals or even States may possess in this same territory. The ICJ chamber in the Frontier Dispute Case (Benin/Niger) observed ‘that the question of the course of the boundary on the bridges is totally independent of that of the ownership of those structures, which belong to the Parties jointly’ (at para. 124). There are other examples of pieces of land that are under the sovereignty of one State and the property of another (the Mundat Forest, under German sovereignty and French ownership; the region of Tiwinza, under Peruvian sovereignty and Ecuadorian ownership). Besides, it is generally accepted that there can be a transfer of property without a transfer of sovereignty and vice-versa. Moreover, a transfer of sovereignty over a territory should not affect private property rights (see German Settlers in Poland [Advisory Opinion] 36 and 38; Certain German Interests in Polish Upper Silesia [Germany v Poland] [Merits] 22 and 42; Land, Island and Maritime Frontier Dispute Case [El Salvador/Honduras: Nicaragua Intervening] [Merits] para. 66; Frontier Dispute [Benin/Niger] [Judgment] para. 118).

2.  Modes of Acquisition of Territory and Titles to Territory

Traditionally, doctrine has referred to the different means of acquiring territorial sovereignty as ‘modes of acquisition of territory’, by drawing an analogy with domestic law for the acquisition of ownership over land. This doctrinal construction was criticized for not being able to embrace all the different ways by which territorial sovereignty is established. At present, the notion of ‘title’ is preferred. It refers generally to the acts or facts that constitute the legal foundation for the establishment of a right over territory. The notion of title is often employed to refer either to the source of a right or to the proof of it (Frontier Dispute Case [Burkina Faso/Republic of Mali] [Judgment] para. 18). Maps provide a good example to illustrate this distinction. When annexed to a treaty of cession of sovereignty, maps have the same value as the treaty. They are an integral element of the relevant ‘title-source’, which is the treaty of cession. However, when maps are not annexed to such a treaty, they merely constitute evidence that a State may invoke in order to prove its title over the territory in dispute. Their probative value will depend, in these circumstances, on factors such as their accuracy, their official character, or the authority establishing them (ibid paras 54–55). Unless stated otherwise, this entry uses the term ‘title’ to mean the source of a right or competence over territory.

B.  The Categorization of Territorial Titles

From the perspective of the rights and competencies bestowed, titles can confer sovereignty, administration, or private ownership over land. In so far as the existence of a title can be linked to the existence of a previous title, titles can be classified as original and derivative titles.

1.  Title of Sovereignty and Title of Administration

Not all relations between a State and a territory can be explained by reference to the notion of sovereignty. Territorial sovereignty refers to the plenitude of a State’s competences over a territory. To possess sovereignty over a territory implies, according to Arbitrator Max Huber in the Palmas Island Arbitration (Palmas [Miangas] Island [Netherlands/United States of America]), that a State is legally entitled to exercise therein the plenitude and exclusivity of State competences. This includes its capacity to make decisions concerning the fate of the territory, ie to alienate it. In other circumstances, a State may administer a territory without being its sovereign. Consequently, to inquire about the way a subject of international law possesses sovereignty or administration over a given territory requires first making a distinction between title of sovereignty and title of administration. States that exercised a mandate (Mandates) under Art. 22 League of Nations Covenant or a trusteeship under Chapter XII of the UN Charter had a title to administer the territories on the basis of the agreements concluded with the League of Nations and the United Nations respectively, without having acquired sovereignty over the territories in question. A State may confer the exercise of authority over a given territory to another State, whilst retaining its sovereignty. This can also be the result of a decision of an international organization or a peace conference.

The distinction between a title of sovereignty and a title of administration lies in the ability of its holder to dispose of the territory concerned. On the one hand, States enjoying a title of sovereignty can exercise the plenitude and exclusivity of rights related to a territory. On the other hand, States that simply administer a territory only possess the specific powers that are conferred on them by the title they hold, ie the mandate or trusteeship agreement, or by the treaty-based and customary rules governing the factual situation in which a State finds itself in control of a territory, such as the case of military occupation (Occupation, Belligerent).

2.  Original and Derivative Titles of Sovereignty

This distinction between original and derivative titles is based on a traditional view about the modes of acquisition of territorial sovereignty. Traditionally, five modes are identified in legal literature as establishing territorial sovereignty, namely cession, effective occupation (effectiveness), accretion, conquest, and prescription. The distinction between the original and derivative acquisition of sovereignty over territory served as a criterion to classify these modes. In territories qualified as terrae nullius, the acquisition of sovereignty is termed ‘original’, whereas for territories already under the sovereignty of another State, it will be referred to as ‘derivative’. On these lines, effective occupation of a terra nullius is considered as an original mode of acquisition of sovereignty, whereas cession is a derivative title of sovereignty. The ICJ endorsed this distinction when dealing with the agreements concluded between local chiefs and colonial powers in the Western Sahara Advisory Opinion. According to the Court, these agreements could not be considered as creating an original title, but were derivative titles of sovereignty (see Western Sahara [Advisory Opinion] paras 79–80).

The distinction between original and derivative titles of territorial sovereignty is of practical value. On the one hand, the legal impact of possession by a State is not the same in the case of a terra nullius as it is in the case of a territory under a State’s sovereignty (see below, the relationship between titles and effectivités). On the other hand, concerning derivative title of sovereignty, the validity of the transfer will depend on whether the previous sovereign possessed a lawful title over the ceded territory. Max Huber emphasized this aspect in Island of Palmas when he noted that ‘[t]he title alleged by the United States of America as constituting the immediate foundation of its claim is that of cession, brought about by the Treaty of Paris, which cession transferred all rights of sovereignty which Spain may have possessed in the region indicated in Art. III of the said Treaty and therefore also those concerning the Island of Palmas (or Miangas). It is evident that Spain could not transfer more rights than she herself possessed’ (at 842).

3.  A Brief Overview of Titles of Sovereignty

One of the five modes of acquisition of territorial sovereignty identified in the legal literature is no longer a valid title (conquest, including debellatio). Another mode is essentially related to previous periods of history (effective occupation, since it can be affirmed that there are generally no longer terrae nullius). The existence of another mode under international law is controversial (acquisitive prescription). Moreover, State practice and case law evince that there are other titles by which territorial sovereignty is established.

10  A title of sovereignty can be established or determined by treaty. This may be a peace treaty, a treaty of cession, or a treaty of delimitation. In addition, special mention should be made of the treaties concluded between colonial powers and local chiefs. The history of colonization reveals that there was a consistent practice of colonial powers entering into treaties with local chiefs in order to transfer the latter’s territories to them. In this regard, the ICJ considered in the Western Sahara Advisory Opinion that ‘such agreements with local rulers, whether or not considered as an actual ‘cession’ of the territory, were regarded as derivative roots of title, and not original titles obtained by occupation of terrae nullius’ (at para 80). The exact scope of those treaties with regard to territorial sovereignty depends on their content (Maritime Delimitation and Territorial Questions between Qatar and Bahrain [Qatar v Bahrain] [Merits] paras 38–44; 95; Boundary between Cameroon and Nigeria Case paras 200–209; Sovereignty over Pedra Branca/Pulau Batu Puteh Case paras 135–136).

11  Attribution by an organ having the capacity to dispose of a given territory is also constitutive of title, either a title of sovereignty or of administration. It may be the decision of an international conference (see Memel Territory Statute, Interpretation of, Case), or of an international organization (see Treaty of Lausanne, Interpretation of [Advisory Opinion]) and UNGA Resolution 390 (V) concerning the federation between Ethiopia and Eritrea, or, in earlier times, a decision of the Pope through papal bulls (see Territory, Discovery). Decisions by tribunals having the capacity to settle ex aequo et bono a territorial dispute can also be constitutive of a title of sovereignty. As a matter of course, other decisions by adjudication (the ICJ or arbitral tribunals) have a declaratory character of what the legal existing situation is and as such they do not create territorial sovereignty.

12  The creation of a new State entails the establishment of a new sovereignty over its territory. Rules relating to the succession of States imply respect of existing boundaries, established by treaty or otherwise. The uti possidetis doctrine involves the transformation of former administrative limits into the boundaries of the new States (Frontier Dispute [Burkina Faso/Mali] paras 20–26; Land, Island and Maritime Frontier Case [El Salvador/Honduras] paras 40–43; Frontier Dispute [Benin/Niger] paras 23–25; Maritime Delimitation between Nicaragua and Honduras in the Caribbean Sea Case [Nicaragua v Honduras] [Judgment] paras 146–67 and 229–36).

13  Unilateral acts can also constitute a title of sovereignty. Despite the controversy on whether the Permanent Court of International Justice (PCIJ) considered the Ihlen Declaration in the Eastern Greenland Case as being a unilateral act or a tacit agreement, it is certain that unilateral acts can create obligations for States (Unilateral Acts of States in International Law). As such, they can have the effect of transferring the sovereignty of a territory from one State to another. Unilateral acts can adopt the form of an explicit renunciation of territorial sovereignty and/or recognition that sovereignty belongs to another State. Acquiescence is a tacit expression of will manifested by unilateral conduct that can lead to the abandonment of sovereignty and its transfer to another State (Sovereignty over Pedra Branca/Pulau Batu Puteh Case paras 120–21).

14  The issue remains whether in a specific case a State can be considered to have acquiesced to the claim of an opposing party. The State that is alleged to have acquiesced should have direct or constructive knowledge of the acts accomplished by the other side. In addition, the acquiescing State must be under a duty to react to them. This will be the case when there is a clear claim of sovereignty over a territory by another State. In the Temple of Preah Vihear Case (Merits), the Court stressed both elements when it said:

Looking at the incident as a whole, it appears to have amounted to a tacit recognition by Siam of the sovereignty of Cambodia (under French Protectorate) over Preah Vihear, through a failure to react in any way, on an occasion that called for a reaction in order to affirm or preserve title in the face of an obvious rival claim. What seems clear is that either Siam did not in fact believe she had any title—and this would be wholly consistent with her attitude all along, and thereafter, to the Annex 1 map and line—or else she decided not to assert it, which again means that she accepted the French claim, or accepted the frontier at Preah Vihear as it was drawn on the map. (At 30–31)

15  As stated by the Court in the Sovereignty over Pedra Branca/Pulau Batu Puteh Case, acquiescence should not be presumed lightly. In each case the clear consent to opposing claims needs to be established. Such consent can be tacit, implicit, or even construed. Nonetheless, it should be established beyond doubt. Admittedly,

silence may also speak, but only if the conduct of the other State calls for a response. Critical for the Court’s assessment of the conduct of the Parties is the central importance in international law and relations of State sovereignty over territory and of the stability and certainty of that sovereignty. Because of that, any passing of sovereignty over territory on the basis of the conduct of the Parties, as set out above, must be manifested clearly and without any doubt by that conduct and the relevant facts. That is especially so if what may be involved, in the case of one of the Parties, is in effect the abandonment of sovereignty over part of its territory. (At paras 121–2)

In order to establish that a State has acquiesced to another’s claims, judges will take into account the consistent conduct of the State regarding the opposing claims. Isolated acts will not be taken into account. In addition, State conduct, such as a protest or the way in which a State continues to treat in its domestic legal system the territory in dispute, may defeat any claim based on acquiescence.

4.  Contested Approaches to Acquisition of Territorial Sovereignty

16  As mentioned above, the existence of acquisitive prescription in international law has been a matter of controversy since early times. In the second half of the 20th century, a doctrinal attempt to overcome this debate was the notion of historical consolidation of title. These two doctrines remain controversial and they merited attention from the International Court of Justice in its most recent case law related to the issue.

(a)  Acquisitive Prescription

17  Acquisitive prescription would be a title leading to the acquisition of territorial sovereignty where the territory in question had a previous holder of sovereignty, and where such acquisition occurs through the possession of a territory à titre de souverain over a prolonged lapse of time. However, these essential elements characterizing acquisitive prescription are problematic and indeed do not constitute the basis for the transfer of sovereignty in a situation in which the territory at issue has belonged to another State.

18  The role of the possession à titre de souverain will be discussed below. Regarding the temporal scope, there is no precise time limit prescribed in international law the lapse of which would be considered as producing a right to acquire sovereignty. In Chamizal (Mexico/United States of America) (see American-Mexican Boundary Disputes and Co-operation), the arbitral award stressed the absence of a fixed deadline for this purpose (at 328). This view is undoubtedly correct as the proponents of this doctrine tend to transpose into international law a domestic legal institution which needs for its implementation not only a fixed deadline, but also the authority of a judge to declare the transfer of title from its legitimate owner to the possessor, or its registration by a competent administrative body. However, nothing prevents States from establishing by treaty a deadline to prescribe, as was the case of the special agreement concluded between Great Britain and Venezuela on the Guyana Boundary Arbitration (Guyana-Venezuela Border Dispute). This constituted a unique case, leading to a decision based on a treaty, rather than on general international law.

19  It has been argued in the doctrine that the role of acquisitive prescription, as a means of transferring title in international law, is fulfilled by other existing legal mechanisms at the international level. Indeed, the critical issue regarding transfer of territorial sovereignty in cases other than formal cession is not only the fact of possession à titre de souverain, but essentially the conduct of the dispossessed holder of title. As long as this title is not extinguished by abandonment (Territory, Abandonment), the possessor State cannot establish its title of sovereignty (Sovereignty over Pedra Branca/Pulau Batu Puteh Case paras 121–22). Therefore, except for the unambiguous situation in which a State formally renounces its sovereignty over a territory, acquiescence will play a decisive role in this regard.

20  Acquisitive prescription has been discussed by the International Court of Justice in territorial disputes, either because it was invoked by one of the parties as a principal or subsidiary title, or because one of the parties accused the other of claiming a prescriptive title (Minquiers and Ecrehos Case [France/United Kingdom] [Judgment]; Temple of Preah Vihear; Sovereignty over Pedra Branca/Pulau Batu Puteh Case). In the Kasikili/Sedudu Island Case (Botswana/Namibia) the Court stressed that the parties had agreed between themselves that acquisitive prescription is recognized in international law and that they had further agreed on the conditions under which title to territory may be acquired by prescription. However, the judgment then stated that ‘the Court need not concern itself with the status of acquisitive prescription in international law or with the conditions for acquiring title to territory by prescription. It considers … that the conditions cited by Namibia itself are not satisfied in this case and that Namibia’s argument on acquisitive prescription therefore cannot be accepted’ (Kasikili/Sedudu Island para. 97). In the Boundary between Cameroon and Nigeria Case, the Court responded to Nigeria’s allegation that, even if Cameroon’s sovereignty was to be upheld, Nigeria still possessed a title of sovereignty arising from the long and peaceful exercise of the sovereignty over Bakassi. The Court emphasized the fact that Nigeria had never held a lawful title of sovereignty and that all the effectivités were contradictory to law and therefore they could not create a valid title of sovereignty for Nigeria (at para. 64). In the Sovereignty over Pedra Branca/Pulau Batu Puteh Case, the Court found that the transfer of sovereignty, ie the loss of sovereignty by Johor/Malaysia and its gain by the United Kingdom/Singapore, was due to the conduct à titre de souverain of the latter, and the conduct of the former which included its failure to respond to the British/Singaporean conduct.

21  A survey of State practice reveals that States are careful not to rely on acquisitive prescription as the main basis of their title to territory. In fact, claims based on acquisitive prescription have the counter-effect of asserting that the original title belonged to the other State. Finally, case law shows that tribunals, rather than examining whether title was acquired through the ‘doctrine of acquisitive prescription’ (as it was called by the Court in Kasikili/Sedudu Island para. 90), focus on State conduct by both sides to the dispute in order to determine whether there has been an abandonment of title and recognition of the other State’s sovereignty through acquiescence.

(b)  Historical Consolidation of Title

22  In order to avoid the theoretical and practical problems created by acquisitive prescription, doctrine in the second half of the 20th century introduced the notion of ‘historical consolidation of title’ (De Visscher; Schwarzenberger; Blum). Whereas acquisitive prescription is grounded on the prolonged lapse of time of possession, the notion of historical consolidation of title focuses on the special interest a territory may have for a given State, and on the general tolerance or recognition by other States of this claim. This notion was grounded on the dictum of the Court in the Fisheries Case (United Kingdom v Norway) where the Court dealt with the claim of Norway to extend its fisheries zone beyond the limits recognized by International Law (Fishery Zones and Limits).

23  In this case, the Court laid great emphasis on the attitude of other States vis-à-vis the Norwegian delimitation system and the benefit of general toleration. In the Boundary between Cameroon and Nigeria Case, the latter invoked historical consolidation of title in order to allege its sovereignty over the Bakassi Peninsula. The Court stressed that ‘the notion of historical consolidation has never been used as a basis of title in other territorial disputes, whether in its own or in other case law’. For the Court, ‘the theory of historical consolidation is highly controversial and cannot replace the established modes of acquisition of title under international law, which take into account many other important variables of fact and law’ (at para 65). Crucially, the Court stressed that where a title of sovereignty exists, effectivités contra legem cannot prevail over it.

C.  Role of Effectivités

24  In all territorial disputes, the parties advance arguments that relate both to the existence of title and to effectivités. The role the latter plays in the settlement of the dispute varies on the basis of different considerations.

1.  Notion of Effectivités

25  Doctrine and case law use the French term effectivités to refer to acts undertaken in the exercise of State authority through which a State manifests its intention to act as the sovereign over a territory. Conditions for valid effectivités relate both to the entity performing them, and the specific nature of the acts performed.

(a)  Entities Allowed to Display State Sovereignty

26  There are no specific rules applicable to territorial disputes that determine when an effectivité is attributable to a State. Thus, rules of general international law must be used to establish whether an act can be attributed to a State or not (State Responsibility). Only persons whose acts are attributable to a State can perform an act undertaken in the exercise of sovereignty on its behalf. Still, some particularities appear in the field under analysis.

(i)  Acts Performed by State Organs

27  Both acts performed by a central government’s organs and those accomplished by other State agents in their official capacity are attributable to a State, and constitute—if other conditions are respected—valid manifestations of sovereignty (Arts 4 and 7 ILC Articles on Responsibility of States for Internationally Wrongful Acts). This does not mean that conduct of different State organs have the same evidentiary weight. The conduct of the central government has greater evidentiary weight than the conduct of local authorities. The conduct of the former is considered to reflect with greater accuracy the intent of the State. Thus, in Temple of Preah Vihear, the Court considered that acts performed by local agents could not override nor nullify the consistent Siamese central authorities’ conduct (at 30).

(ii)  Acts Performed by Private Entities

28  The acts of private entities are in principle not attributable to a State. Thus, they cannot create a title of sovereignty for a State. Confronted with acts of private individuals in a territorial dispute, a judge will consider whether these persons have been allowed to exercise elements of governmental authority. According to the tribunal in the Dubai/Sharjah Border Arbitration, ‘the effective control of a territory does not depend on the actions of private individuals per se but only on the actions of public authorities or individuals acting on their behalf’ (at 606).

29  Furthermore, the presence of a population on a territory is not in itself determinative for deciding which State is the holder of the territorial title of sovereignty. In the Land, Island and Maritime Frontier Case (El Salvador/Honduras) the tribunal defined its task as consisting in the definition of the boundaries. The fact that thousands of Hondurans or Salvadorians were on the ‘wrong side’ of the boundary as established by the tribunal was considered irrelevant to its delimitation (at para 97). The Court followed the same approach in Boundary between Cameroon and Nigeria Case (at para 67). Conversely, the acts of State organs, regulating the presence of individuals on a territory, may be considered as effectivités depending on the nature of such acts.

30  When a State authorizes an individual or a chartered company to perform sovereign acts on their behalf, these acts are attributable to the State. Such acts can be considered as effectivités. In Island of Palmas the sole arbitrator Max Huber stressed that

[t]he acts of the East India Company [Generale Geoctroyeerde Nederlandsch Oost-Indische Compagnie], in view of occupying or colonizing the regions at issue in the present affair must, in international law, be entirely assimilated to acts of the Netherlands State itself. From the end of the 16th till the 19th century, companies formed by individuals and engaged in economic pursuits (Chartered Companies), were invested by the State to whom they were subject with public powers for the acquisition and administration of colonies. (At 858)

See also Sovereignty over Pedra Branca/Pulau Batu Puteh Case para 21. Nowadays, the acts of such companies would be attributable to a State pursuant to Art. 5 ILC Articles on State Responsibility.

(b)  Material Acts (Corpus) Displaying Sovereignty in International Case Law

31  There is a wide range of acts that may constitute manifestations of the exercise of State sovereignty. They can be classified according to the three traditional powers of a State, namely legislative power, executive power, and judicial power. According to the PCIJ in the Eastern Greenland Case, ‘[l]egislation is one of the most striking forms of the exercise of sovereign power’ (at 48). In the case concerning the Sovereignty over Pulau Ligitan and Pulau Sipadan Case (Indonesia/Malaysia), Malaysian sovereignty was declared by the Court based on its legislation regulating turtle egg fishing. The Court was of the opinion that ‘both the measures taken to regulate and control the collecting of turtle eggs and the establishment of a bird reserve must be seen as regulatory and administrative assertions of authority over territory which is specified by name’ ([Judgment] para. 145). Administrative and judicial acts have also been taken into account in the Minquiers and Ecrehos Case (France/United Kingdom). In this case, the Court took into account the fact that the tribunal of Jersey had exercised jurisdiction over the Ecrehos for more than 100 years. As far as the construction of lighthouses and other aids to navigation is concerned, although they do not constitute per se an act manifesting the exercise of sovereignty (at 70–1), they have been considered as acts à titre de souverain in the case of very small islands in the Case between Qatar and Bahrain (at para. 197). Military activities, police surveillance (Rann of Kutch Arbitration [Indo-Pakistan Western Boundary] 558) and naval patrols (Sovereignty over Pedra Branca/Pulau Batu Puteh Case paras 240-43) were considered to be effectivités. Official publications, depending on their context, may or may not constitute evidence of effectivités.

(c)  Subjective Element: The Intent to Act as a Sovereign

32  As discussed above, there exist different statuses for the exercise of State activity in relation to territory. Acts accomplished as a territory administrator are not effectivités, because they are not carried out with the intent to act as a sovereign. For instance, acts performed by a trustee in accordance with the system enshrined in Chapter XII of the UN Charter, or acts performed by a belligerent occupant, are not performed à titre de souverain. As such, they cannot be taken into account in a territorial dispute as having probative value for the establishment of a title of sovereignty.

2.  Role of Effectivités and Title in Territorial Disputes

33  Although effectivités play a significant role in territorial disputes, they cannot per se and automatically be assigned the function of creating title in all circumstances. The impact of effectivités in disputes will depend on a number of different factors. They may themselves constitute a title; they may be evidence of the existence of a title; or they may be unable to displace a title.

(a)  Relationship Between Effectivités and a Title to Territory

34  The Frontier Dispute (Burkina Faso/Mali) is the locus classicus on the relationship between titles and effectivités. According to the Court,

[w]here the act corresponds exactly to law, where effective administration is additional to the uti possidetis iuris, the only role of effectivité is to confirm the exercise of the right derived from a legal title. Where the act does not correspond to the law, where the disputed territory is effectively administered by a State other than the one possessing the legal title, preference should be given to the holder of the title. In the event that the effectivités does not co-exist with any legal title, it must invariably be taken into consideration. Finally, there are cases where the legal title is not capable of showing exactly the territorial expanse to which it relates. The effectivité can then play an essential role in showing how the title is interpreted in practice. (At para. 63)

35  Although the Chamber of the Court was dealing in that case with uti possidetis, its statement concerning the relationship between effectivités and title is authoritative on the framework to apply in order to examine the relationship between effectivités and a legal title in general. The Court has applied this framework in other cases in which uti possidetis was or was not at issue (Land, Island and Maritime Frontier Case paras 61–2; Sovereignty over Pulau Ligitan and Pulau Sipadan para. 126; Boundary between Cameroon and Nigeria Case para. 68; Frontier Dispute [Benin/Niger] para. 47; and Maritime Delimitation between Nicaragua and Honduras in the Caribbean Sea Case [Nicaragua v Honduras] paras 151–8).

36  To summarize, in a territorial dispute, the legal value of effectivités is to be assessed according to the existence or not of a legal title. When there is no title of sovereignty over a territory, or that title cannot be determined by other means, effectivités can create a territorial title. Whenever a title of sovereignty exists, it has primacy over contradictory effectivités of another State. If they are unlawful, effectivités cannot in themselves create a title of sovereignty. In the Boundary between Cameroon and Nigeria Case,

the Court concludes that the situation was essentially one where the effectivités adduced by Nigeria did not correspond to the law, and that accordingly ‘preference should be given to the holder of the title. (At para. 70)

In other cases, effectivités can have probative value or play an interpretative function of the title concerned, or a residual function where they are considered as being ‘as good as a title’, to use the words of Max Huber in Island of Palmas (at 839).

37  The Sovereignty over Pedra Branca/Pulau Batu Puteh Case is the only territorial case settled by the Court after the Burkina Faso/Mali judgment in which the Court did not explicitly refer to the traditional relationship between titles and effectivités. Having recognized that Malaysia held an original title of sovereignty over Pedra Branca/Pulau Batu Puteh, the Court considered that there was a later transfer of sovereignty in favour of Singapore. However, in this case the Court did not depart from the traditional approach it earlier had followed on the relationship between titles and effectivités. Indeed, in this case the Court emphasized the importance of consent in the field of territorial change and for the notions of abandonment and acquiescence as the legal foundations of this transfer of sovereignty. It mentioned that in the 1953 letter of the Sultanate of Johor the latter indicated that it did not claim ‘ownership’ over Pedra Branca, and that this constituted the beginning of a ‘convergent evolution of the positions of the Parties regarding title to Pedra Branca/Pulau Batu Puteh’ (at para. 276).

38  The approach taken by the Court here is also consistent with what the Court stated in the Boundary between Cameroon and Nigeria Case. According to the Court,

some of Nigeria’s activities—the organization of public health and education facilities, policing, the administration of justice—could, as argued by it, normally be considered to be acts à titre de souverain. The Court notes, however, that, as there was a pre-existing title held by Cameroon in this area of the lake, the pertinent legal test is whether there was thus evidenced acquiescence by Cameroon in the passing of title from itself to Nigeria (at para. 67).

(b)  Effectivités and State Conduct

39  State conduct is a very important part of any analysis of a territorial dispute. State conduct comprises both effectivités for a State, and the reaction to them by another State. It may have a declarative effect, by restating the rights of the respective parties to a dispute. State conduct can also create an estoppel. State conduct in relation to a territorial dispute may also entail a renunciation of a right. This may occur when a State decides not to claim its sovereign rights. Conversely, State conduct can also serve to maintain a State’s rights. This will be the case when a State, which has lost the control of its territory, continues to claim it by issuing protests, enacting legislation or any other relevant conduct regarding this territory by which it manifests its intention to remain the sovereign. State conduct may also serve to transfer a title of sovereignty. This may occur either through formal consent or through acquiescence.

D.  Role of Fundamental Principles of International Law

40  A title to territory or a claim to such a title can be influenced by others rules and principles of international law which are relevant to this field. This is the case in particular for fundamental principles of international law. Contemporary principles such as the right to self-determination and the prohibition of the use of force have produced significant changes in the law relating to the establishment of territorial sovereignty.

1.  Principle of Territorial Integrity

41  ‘Between independent States, respect for territorial sovereignty is an essential foundation of international relations’ (Corfu Channel Case [United Kingdom of Great Britain and Northern Ireland v Albania] [Merits] 35). More recently, the Court recalled that ‘the principle of territorial integrity is an important part of the international legal order’ (Accordance with International Law of the Unilateral Declaration of Independence in Respect of Kosovo [Advisory Opinion] para. 80; Kosovo).

42  The illegal character of acts performed in violation of a State’s territorial integrity (Territorial Integrity and Political Independence) has far-reaching consequences in the law governing acquisition of territorial sovereignty: a territory possessed as a result of a violation of the principle of territorial integrity cannot be considered as belonging to the possessor. Indeed, such a possession will be tainted with illegality. Consequently, the principle of territorial integrity strengthens the view that, for territories under State sovereignty, only consent—either expressed implicitly through acquiescence, or explicitly by a formal act like the conclusion of a treaty—can transfer the territorial title.

2.  Principle of Self-determination

43  Self-determination is the most revolutionary of the principles enshrined in the UN Charter, since for the first time it grants to a specific community, a ‘people’ (as this term is understood in international law), the right to modify territorial sovereignty through the change of the status of the territory upon which self-determination is exercised. This occurs through the creation of a newly independent State, or its integration or free association with a new or an existing one.

44  The principle of self-determination produces two major effects as far as territorial sovereignty is concerned.

45  First, the principle has an impact on territorial titles formerly held by colonial powers. By applying the rules of intertemporal law, colonial titles can no longer be maintained as they are at variance with the principle. Former colonial powers’ titles of sovereignty were transformed into titles of administration. The Friendly Relations Declaration (1970) appended to UNGA Resolution 2625 (XXV) consecrated this transformation of colonial titles by asserting that ‘[t]he territory of a colony or other Non-Self-Governing Territory has, under the Charter, a status separate and distinct from the territory of the State administering it’ (Non-Self-Governing Territories).

46  Second, the right to self-determination provides the basis for the sovereignty of the ‘people’ over their territory. Resolution 2625 even provides that a ‘people’ have a right to territorial integrity by stipulating that ‘Every State shall refrain from any action aimed at the partial or total disruption of the national unity and territorial integrity of any other State or country’.

47  In this regard, it is crucial to define the notion of ‘people’ who have a right to exercise self-determination (Peoples). On the basis of the analysis of the Court in the Western Sahara Advisory Opinion, not every population inhabiting a territory constitutes a ‘people’ entitled to self-determination (at para. 59). The practice of the UN shows that within the Organization this right was applied only to people living under colonial or alien domination. Existing States are considered to be constituted by a single people, unless the State itself recognizes that it is comprised of a plurality of peoples entitled to exercise self-determination. If understood in this manner, it is possible to reconcile the right to exercise self-determination with the principle of territorial integrity. However, there is debate concerning the scope of the seventh paragraph dealing with self-determination in the Friendly Relations Declaration, which contains the ‘saving clause’ of territorial integrity of States (see Secession).

3.  Principle of the Prohibition of the Use of Force

48  The inclusion of a general prohibition of the use of force in international relations by the Charter of the United Nations has had a considerable impact on the legal regulation of territorial change. As a consequence, ‘[n]o territorial acquisition resulting from the threat or use of force shall be recognized as legal’ (Friendly Relations Declaration). See also the definition of aggression embodied in UNGA Resolution 3314 [XXIX]). Consequently, formerly valid titles of sovereignty such as conquest and debellatio have ceased to exist in international law.

E.  Technical Rules in Territorial Disputes

49  Technical rules such as the critical date and inter-temporal law do not exclusively operate in the field of acquisition of territorial sovereignty, although they play a significant role.

1.  Critical Date

50  Territorial claims imply a succession of events occurring over a considerable span of time. A tribunal is therefore obliged to determine the moment in time when the parties’ claims must be legally assessed. This moment in time is the critical date. The determination of the critical date may have a significant impact both on the applicable law and on the facts considered to be relevant to the dispute. In the Sovereignty over Pedra Branca/Pulau Batu Puteh Case, the Court considered that the critical date serves to ‘distinguish … between those acts which should be taken into consideration for the purpose of establishing or ascertaining sovereignty and those acts occurring after such date’ (at para. 32).

51  In practice, facts occurring after the critical date will not be taken into account to determine the title of sovereignty. A State party to a territorial dispute may attempt to improve its legal position by performing self-serving acts. Exceptionally, international tribunals have taken into account some facts that occurred after the critical date. These facts have the peculiar feature of being the continuation of activities previously undertaken by the States Parties to the dispute, and do not improve the legal position of any of the parties to the disputes (ibid para. 32). Indeed, what is essential is the probative value of such acts, ie their coherence with positions held before the critical date. In particular, acts performed after the critical date cannot be invoked as an independent source of title. This is of particular relevance with regard to acquiescence.

52  In general, the critical date is determined when the dispute crystallized, ie when the parties formally opposed each other’s claim. This generally occurs when one side asserts its sovereignty and the other side protests for the first time, or when the first protest by one State is rejected by the other (ibid para. 33). However, there can be particular critical dates depending on the titles claimed. For disputes relating to uti possidetis, the critical date will be the date of accession to independence, in order to determine the existing situation that was inherited by the successor States concerned.

2.  Intertemporal Law

53  Intertemporal law plays an important role in addressing the effect of the evolution of the international legal system on territorial titles. According to Max Huber,

[a]s regards the question which of different legal systems prevailing at successive periods is to be applied in a particular case (the so-called inter-temporal law), a distinction is to be applied between the creation of rights and the existence of rights. The same principle which subjects the act creative of a right to the law in force at the time the right arises, demands that the existence of the right, in other words its continued manifestation, shall follow the conditions required by the evolution of law. (Island of Palmas 846)

Thus, to determine whether a State acquired sovereignty over a territory in the 19th century, the relevant rules of international law that existed at that period must be applied. However, to decide whether sovereignty is still maintained nowadays requires examining whether it still complies with the rules of international law that have since evolved. In this manner, the first part of the rule of intertemporal law applies only to acts and facts that give rise to a title of sovereignty, whereas the second part of intertemporal law applies to the legal situation established by this title.

54  Sovereignty acquired by conquest in the 19th century must be analysed on the basis of the conditions set down by international law for such an acquisition at that time, and not by applying the rules of the prohibition of the use of force existing in contemporary international law. However, the maintenance of sovereignty must conform to the present legal situation. Consequently, sovereignty acquired over a territory in conformity with the international legal system existing at the time of the acquisition can be superseded by the evolution of international law. For instance, the recognition of the existence of a people entitled to exercise self-determination will render the title of sovereignty unopposable.

F.  Conclusion

55  General international law has established particular rules that govern the acquisition and loss of territorial sovereignty and administration. There is a plurality of ways by which States become the sovereign or administrator of a given territory. These means are known as titles of sovereignty or administration. With some exceptions, there is no major controversy in State practice as to the existence of these titles. Effectivités alone are generally not determinative. However, coupled with acquiescence, they can lead to territorial change. The new fundamental principles of international law that emerged from the UN Charter have deeply impacted upon the establishment of sovereignty over territory. The acquisition of territorial sovereignty entails a combination of analysis of the titles invoked by the State concerned as well as its conduct, in order to determine whether the title may be retained or transferred. The importance of what is at stake—territorial sovereignty—requires clear proof of both its acquisition and loss.

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