                     134

                                    SEPARATE OPINION OF JUDGE YUSUF

                        Uti possidetis juris and the OAU/AU principle on respect of borders are neither
                     identical nor equivalent — The Cairo Resolution and founding instruments of the
                     OAU and AU do not refer to uti possidetis juris — The two principles must be
                     distinguished in light of their different origins, purposes, legal scope and nature —
                     The Court should have cleared up this confusion — The OAU/AU principle is not
                     concerned with the relationship between title and effectivités — Nor does it confer
                     preference on one over the other — The reference to territorial integrity in the
                     OAU/AU founding instruments cannot be interpreted as implicitly containing the
                     principle of uti possidetis juris — It is the inviolability of boundaries which is
                     implicit in territorial integrity — Inviolability does not mean invariability or
                     intangibility — The 1987 delimitation agreement between the Parties distinguishes
                     this case from previous frontier delimitation cases — Uti possidetis juris had no
                     role to play in this case — This should have been recognized in the Judgment.

                                                     I. Introduction

                        1. While I am in agreement with the decision of the Court, I feel
                     obliged to deal in this opinion with certain issues, which the Court did
                     not adequately address in the reasoning of the Judgment, particularly as
                     regards the applicable principles invoked by the Parties in their pleadings
                     before the Court (see paragraph 63 of the Judgment).
                        2. In its analysis of the rules and principles invoked by the Parties in
                     their Special Agreement, the Court refers to the following three principles
                     in paragraph 63 of the Judgment : (a) the principle of intangibility of
                     boundaries inherited from colonization ; (b) the principle of uti possidetis
                     juris ; and (c) the principle of respect of borders existing on achievement
                     of independence adopted by the Organization of African Unity (OAU) in
                     its Resolution AHG/Res. 16 (I) in 1964 at the first session of the Confer-
                     ence of African Heads of State and Government held in Cairo, Egypt
                     (hereinafter, the “Cairo Resolution”), and later enshrined as Article 4 (b)
                     in the Constitutive Act of the African Union (AU).

                        3. Apart from the fact that the Judgment does not explain the legal
                     effect and implications of these principles in the instant case or the man-
                     ner in which they are to be applied to the boundary dispute between the
                     Parties, the Court appears to treat them as being interchangeable or at
                     least equivalent in their legal nature, scope and effects. The assumption of
                     equivalence, particularly between uti possidetis juris and the OAU/AU
                     principle of respect of borders existing on achievement of independence,

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                     is based on a dictum of the Chamber of the Court in its Judgment in the
                     case concerning the Frontier Dispute (Burkina Faso/Republic of Mali) of
                     22 December 1986.
                        4. The Chamber of the Court formed to deal with the above‑mentioned
                     case stated, inter alia, as follows :
                             “The Charter of the Organization of African Unity did not ignore
                          the principle of uti possidetis, but made only indirect reference to it in
                          Article 3, according to which member States solemnly affirm the prin-
                          ciple of respect for the sovereignty and territorial integrity of every
                          State. However, at their first summit conference after the creation of
                          the Organization of African Unity, the African Heads of State, in
                          their Resolution mentioned above (AGH/Res. 16 (I)), adopted in
                          Cairo in July 1964, deliberately defined and stressed the principle of
                          uti possidetis juris contained only in an implicit sense in the Charter
                          of their organization.” (Frontier Dispute, Judgment, I.C.J. Reports
                          1986, pp. 565‑566, para. 22.)
                        5. Following the above statement by the Chamber of the Court, it appears
                     to have been widely assumed, not least by the Court itself in subsequent cases
                     concerning frontier delimitation between African States, that the principle of
                     respect of boundaries existing on achievement of independence adopted by
                     the OAU in its Cairo Resolution, and later by the AU, constitutes an African
                     uti possidetis juris which is identical to the principle of Spanish‑American
                     origin. For example, in its Judgment of 12 July 2005, the Chamber of the
                     Court in the case concerning the Frontier Dispute (Benin/Niger), after refer-
                     ring to the 1986 Judgment, stated that the principle of uti possidetis juris had
                     been recognized on several occasions in the African context and that “it was
                     recognized again recently, in Article 4 (b) of the Constitutive Act of the
                     African Union” (I.C.J. Reports 2005, p. 108, para. 23).
                        6. It is my view that uti possidetis juris and the principle endorsed by the
                     OAU in the Cairo Resolution, and later inscribed in the Constitutive Act of
                     the AU, are neither identical nor equivalent. Although the Court, in the pres-
                     ent Judgment (para. 63), has slightly moved away from the above‑quoted
                     dicta of the 1986 and 2005 Judgments equating uti possidetis juris to the
                     Cairo Resolution and to Article 4 (b) of the Constitutive Act of the AU, I
                     am still of the view that the difference between the two principles merits fur-
                     ther elucidation so that they may not be similarly confounded in the future.

                                     II. The Cairo Resolution and OAU/AU
                                              Principles on Borders

                        7. It is instructive to start with the text of the Cairo Resolution and of
                     the OAU/AU principles referred to in the above‑mentioned Judgment of
                     the Chamber of the Court. Under Article III, paragraph 3, of the OAU
                     Charter, the member States declared their adherence to the principle of
                     “respect for the sovereignty and territorial integrity of each State and for
                     its inalienable right to independent existence”.

                     95

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                       8. The text of the Cairo Resolution entitled “Border Disputes among
                     African States” reads as follows :
                             “Considering that border problems constitute a grave and perma-
                          nent factor of dissension ;
                             Conscious of the existence of extra‑African manoeuvres aimed at
                          dividing African States ;
                             Considering further that the borders of African States, on the day
                          of their independence, constitute a tangible reality ;
                             Recalling the establishment in the course of the Second Ordinary
                          Session of the Council of the Committee of Eleven charged with
                          studying further measures for strengthening African Unity ;
                             Recognising the imperious necessity of settling, by peaceful means
                          and within a strictly African framework, all disputes between African
                          States ;
                             Recalling further that all Member States have pledged, under Arti-
                          cle IV of the Charter of African Unity, to respect scrupulously all
                          principles laid down in paragraph 3 of Article III of the Charter of
                          the Organization of African Unity ;
                         1. Solemnly reaffirms the strict respect by all Member States of the
                              Organization for the principles laid down in paragraph 3 of Arti-
                              cle III of the Charter of the Organization of African Unity ;
                         2. Solemnly declares that all Member States pledge themselves to
                              respect the borders existing on their achievement of national inde-
                              pendence.”
                       9. Article 4 (b) of the Constitutive Act of the AU lists as one of the
                     principles of the Union the “respect of borders existing on achievement of
                     independence”.

                              III. The OAU/AU Principles and Uti Possidetis Juris

                        10. As a preliminary remark, it may be noted that none of the official
                     documents of the OAU or of its successor organization, the AU, relating
                     to African conflicts, territorial or boundary disputes, refers to or mentions
                     in any manner the principle of uti possidetis juris. As stated by a keen
                     observer of the origins and evolution of Pan‑African organizations, and
                     an advocate of an “uti possidetis africain”, “it would be important to under
                     line that the American precedent was never explicitly invoked during
                     the travaux préparatoires of the Addis Ababa Conference, and even
                     less by the Heads of State in their inaugural speeches” 1. Equally signifi-
                     cant are the differences between the two principles with regard to their
                     origin and purpose, their legal scope and content and their legal nature.

                        1 B. Boutros-Ghali, L’Organisation de l’unité africaine, Paris, Armand Colin, 1969, p. 48,

                     at footnote 3. The French text reads as follows : « il convient de souligner que le précédent
                     américain n’a jamais été expressément invoqué lors des travaux préparatoires de la conférence
                     d’Addis Abéba, et encore moins par les Chefs d’Etat dans leurs discours d’inauguration ».

                     96

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                                            1. Differences in Origin and Purpose
                        11. The Spanish‑American Republics, which emerged from coloniza-
                     tion in the early nineteenth century, adopted the principle of uti possidetis
                     juris in order to address an issue of acquisition of title to territory, which
                     was not satisfactorily resolved by any of the traditional modes of acquisi-
                     tion of title in classical international law 2. The classical modes of acqui-
                     sition of territory — occupation, prescription, cession, accretion and
                     subjugation — did not provide for the situation in which a new State
                     came into existence through decolonization 3. In particular, the main
                     question for the new Republics revolved around the issue of who pos-
                     sessed the legal title in regions which were sparsely populated and in
                     which the limits were vaguely known or inadequately defined. To deal
                     with this problem, it was decided by the former Spanish colonies, as
                     described by the Swiss Federal Council in the Colombia‑Venezuela Arbi
                     tral Award of 1922, that these regions would be :
                          “reputed to belong in law to whichever of the Republics succeeded to
                          the Spanish province to which these territories were attached by virtue
                          of the royal ordinances of the Spanish mother country. These territo-
                          ries, although not occupied in fact, were by common consent deemed
                          as occupied in law, from the first hour, by the new Republic.” 4

                        Thus, the primary purpose of this principle was to ensure that there
                     was no terra nullius open to occupation by foreign imperial powers in
                     Spanish America 5.
                        12. The second objective of uti possidetis juris was to establish a method
                     or criterion for boundary delimitation where two States, formerly subject
                     to the same metropolitan power, emerged from decolonization. This was
                     achieved by upgrading former administrative limits to international fron-
                     tiers among the new Republics. As stated by the Chamber of the Court in
                     the Land, Island and Maritime Frontier Dispute (El Salvador/Honduras :
                     Nicaragua intervening) : “uti possidetis juris is essentially a retrospective
                     principle, investing as international boundaries administrative limits
                     intended originally for quite other purposes” (Judgment, I.C.J. Reports
                     1992, p. 388, para. 43).

                        2 In Land, Island and Maritime Frontier Dispute (El Salvador/Honduras : Nicaragua

                     intervening), the Chamber of the Court characterized uti possidetis juris as follows : “Thus
                     the principle of uti possidetis juris is concerned as much with title to territory as with the
                     location of boundaries . . .” (Judgment, I.C.J. Reports 1992, p. 387, para. 42).
                        3 See R. Y. Jennings, The Acquisition of Territory in International Law, Manchester

                     University Press, 1963, pp. 7‑11 and 37.
                        4 Colombia-Venezuela Arbitral Award, United Nations, Reports of International Arbi

                     tral Awards (RIAA), Vol. I, 223, p. 228 [translation].
                        5 See the separate opinion of Judge ad hoc G. Abi-Saab in Frontier Dispute (Burkina

                     Faso/Republic of Mali), where he describes the dual purpose of the principle of uti possi
                     detis (I.C.J. Reports 1986, p. 661, para. 13).

                     97

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                        13. The situation faced by the African countries in the early 1960s sub-
                     stantially differed from that of the Spanish‑American Republics where
                     only administrative boundaries established by Spanish royal ordinances
                     and other Spanish legal instruments existed. First, at the time of indepen-
                     dence in the 1960s, there were no regions or territories in Africa which
                     were reputed to be unexplored or which could be considered as terra nul
                     lius and thus open to acquisition of title through occupation by foreign
                     imperial powers.

                        14. Secondly, the origin of the post‑independence boundaries of Afri-
                     can States was varied. It is estimated that only one-fourth of the bound-
                     aries of African States had an intra‑colonial administrative character 6.
                     The majority of the boundaries of the newly‑independent African States
                     were inter‑colonial boundaries established through treaties concluded
                     between different colonial powers. The boundaries of two of the founding
                     members of the OAU, Ethiopia and Liberia, neither of which had ever
                     been colonized, were mainly fixed through their own bilateral treaties
                     with the colonial or administering powers of their neighbours. There were
                     also the trust territories under the United Nations Charter, which were
                     not considered colonial territories, since the administering authority
                     entered into a Trusteeship Agreement with the United Nations in respect
                     of the territory concerned and any alterations to it had to be approved in
                     accordance with the provisions of Chapter XII of the Charter 7.

                         15. The diversity of the boundary régimes which existed on the
                      frican continent at the time of independence, and the aversion
                     A
                     of the newly‑    independent African States to the legitimization
                     of  colonial law in inter‑African relations, led the OAU, and later
                     the AU, to craft its own principle, the legal scope and nature
                     of which will be discussed below. Thus, the lack of reference to uti
                     possidetis was not due to a lack of awareness by the OAU member
                      States of the existence of uti possidetis juris as a principle or
                      of its use by the Spanish‑American Republics following their own
                      decolonization a century earlier 8. Rather, different situations, and his-

                        6 M. Foucher, “Les questions territoriales et frontalières en Afrique (1964-2010) :

                     la réaffirmation des frontières” in Emilia Robin-Hivert, Georges-Henri Soutou (eds.),
                     L’Afrique indépendante dans le système international, Paris, PUPS, 2012, p. 62.
                        7 See Articles 79, 83 and 85 of the UN Charter.
                        8 B. Boutros-Ghali, after lamenting that uti possidetis juris was not specifically

                     mentioned in the OAU Charter, states that :
                             “There may have been fears that the mention of this principle would not receive
                          unanimous approval, or that it may be said (as it already has been) that the
                          Addis Ababa Charter was an explicit ratification of the Treaty of Berlin. Whatever
                          may be the reason, the adoption of the principle of uti possidetis would have been
                          an important step toward expanding the role of international law in Africa.” See
                          B. Boutros-Ghali, “The Addis Ababa Charter”, 35 (3) International Conciliation 5,
                          1964, p. 29.

                     98

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                     torical circumstances, dictated the adoption of different legal rules and
                     principles.
                       16. It should also be recalled that despite its title of “Border Disputes
                     among African States”, the main objective of the Cairo Resolution was to
                     discourage territorial annexation by force as well as irredentist,
                     pan‑nationalist and secessionist claims. This is evidenced by the fact that
                     the only two countries that voted against the resolution were Somalia and
                     Morocco, both of which had, at the time, irredentist claims against their
                     neighbours, while all the other member States of the OAU, most of whom
                     had boundary disputes amongst them, supported the resolution, which
                     provided for peaceful methods and modalities of resolving such disputes.

                        17. Moreover, although it may sound paradoxical, the African princi-
                     ple of respect for the boundaries existing at the time of independence is
                     closely intertwined with the manner in which the OAU decided to deal
                     with the Pan‑African vision of integration and unity among all Afri-
                     can States. The Pan‑African vision, which was advocated by African lead-
                     ers in the period before independence, was to render boundaries less
                     significant through the unification of the peoples of the continent. For
                     example, the Pan‑African congress, in a resolution adopted in 1958 in
                     Accra, Ghana, denounced “the artificial frontiers drawn by imperialist
                     powers to divide the peoples of Africa, particularly those which cut across
                     ethnic groups and divide people of the same stock”, and called for “the
                     abolition or the adjustment of such frontiers at an early date” 9.

                        18. The OAU neither adopted this vision, nor did it completely aban-
                     don it. A tinge of the Pan‑African vision was preserved in the form of
                     commitments to work towards African Unity. This is explicitly mentioned
                     even in the Cairo Resolution, where reference is made in the preamble to
                     the establishment “of the Committee of Eleven charged with studying fur-
                     ther measures for strengthening African Unity”. The task of this Com-
                     mittee was to propose political action which would further promote the
                     unity and solidarity of the African States 10. Thus, in the Cairo Resolu-
                     tion, the preservation of the boundaries existing at the time of indepen-
                     dence is somehow balanced by the continued efforts towards closer
                     African political and economic integration.

                       19. Consequently, it may be said that the principle of respect for
                     boundaries in the Cairo Resolution places the boundaries existing at the
                     time of independence in a “holding pattern”, particularly to avoid armed
                     conflict over territorial claims, until a satisfactory and peaceful solution is
                     found by the Parties to a territorial dispute in conformity with interna-

                       9 For the text of the resolution, see C. Legum, Pan Africanism : A Short Political

                     Guide, London, Pall Mall Press, 1962, pp. 229‑232.
                       10 See Z. Cervenka, The Organization of African Unity and Its Charter, Prague,

                     Acadamia, 1968, pp. 55‑60.

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                     tional law, or until such time as closer integration and unity is achieved
                     among African States in general, or between the neighbouring countries
                     in particular, in keeping with the Pan‑African vision. As such, it implies a
                     prohibition of the use of force in the settlement of boundary disputes and
                     an obligation to refrain from acts of seizure of a portion of the territory
                     of another African State.

                                          2. Differences in Legal Scope and Content
                        20. As explained above, uti possidetis juris had two important aspects
                     as formulated by the Spanish‑American Republics at the time of their
                     independence : the absence of terra nullius in their territories and the
                     mutual acceptance by the newly‑independent Republics of the lines which
                     formerly delimited the internal administrative divisions or sub‑divisions
                     of Spanish provinces, intendencias and capitanias as their international
                     boundaries. The latter component has acquired more relevance in inter-
                     national law over the years, and has come to be regarded as the core ele-
                     ment of uti possidetis juris. However, as a criterion for the delimitation of
                     boundaries, its application has been mostly limited to converting into
                     international boundaries the administrative boundaries inherited from
                     the same colonial power or the internal boundaries of States emerging
                     from the dissolution of a larger entity.

                        21. Thus, even in Latin America, Brazil, which gained its independence
                     from a different colonial power (Portugal) and shared former inter‑colo-
                     nial rather than intra‑colonial boundaries with its neighbours, adopted
                     the markedly different concept of uti possidetis de facto, which gives pref-
                     erence to effective possession rather than legal title based on Spanish
                     colonial legislation 11. As stated by H. Accioly :

                              “While the former Spanish colonies could indeed rely on this legal
                           invention, because it would be open to them to discuss their respective
                           territorial claims among themselves on the basis of laws or royal grants
                           emanating from their common metropole, it is clear that they could
                           not rely on such titles against Brazil, since these were not applicable
                           to the latter, and hence such a basis would have no legal value.” 12

                        11 As was stated by the Chamber of the Court in Land, Island and Maritime Frontier

                     Dispute (El Salvador/Honduras : Nicaragua intervening) : “It should be recalled that when
                     the principle of the uti possidetis juris is involved, the jus referred to is not international law
                     but the constitutional or administrative law of the pre-independence sovereign, in this case
                     Spanish colonial law . . .” (Judgment, I.C.J. Reports 1992, p. 559, para. 333.)
                        12 H. Accioly, “Le Brésil et la doctrine de l’uti possidetis”, Revue de droit international,

                     Vol. 15, 1935, pp. 36‑45, at p. 45. [Translation by the Registry.]

                     100

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                        22. Unlike the uti possidetis juris of Spanish‑America, the OAU/AU
                     principle of respect for boundaries can only be interpreted as a broad
                     principle which affirms the acceptance by all African States of the existing
                     boundaries of the sovereign independent States that came together to
                     form the OAU and later the AU. The OAU/AU principle does not
                     address the issue of title to inadequately defined regions or areas in fron-
                     tier zones or physically non‑existent boundaries. Nor does it lay down a
                     specific peaceful method or criterion to be used for ascertaining the pedi-
                     gree of disputed boundaries or for attributing title to territory. The spe-
                     cific methods to be used for the peaceful settlement of boundary disputes
                     are left to be determined, on a case by case basis, by the States concerned.
                     Uti possidetis juris could, of course, be one such principle, but it would
                     have to be specifically agreed upon by the Parties to the dispute.

                        23. Moreover, the relevant territory, the boundaries of which have to
                     be respected under the OAU/AU principle, is neither the one that existed
                     during the colonial period as a colony nor the pre‑colonial historical ter-
                     ritory of African States, but has rather to be understood as the post‑inde-
                     pendence territory of the OAU/AU member States. Indeed, as a result of
                     the exercise of the right to self‑determination consecrated under the Char-
                     ter of the United Nations, the peoples of African colonies or trusteeship
                     territories were often able to freely determine their political status prior to
                     independence in one of the following ways : the formation of a single sov-
                     ereign State ; the division of a trust territory into two separate States ; the
                     unification of part of a colony or trust territory with a neighbouring
                     State ; the unification of two colonies or of a trust territory with a colony.

                        24. This situation sometimes resulted in the emergence of a single inde-
                     pendent State from the union of a former colony with a former trust ter-
                     ritory, e.g., British and Italian Somaliland. It has also led to the merger of
                     a trust territory or a part thereof with another colonial or trust territory ;
                     for example, the northern part of the trust territory of Cameroon under
                     British administration merged with Nigeria, while the southern part opted
                     for integration with the trust territory of Cameroon under French admin-
                     istration. Similarly, the British‑administered trust territory of Togoland
                     was united with Ghana following a plebiscite under the auspices of the
                     United Nations. On other occasions, two independent States emerged
                     from the division of a single trust territory, e.g., the case of Rwanda and
                     Burundi.

                        25. It is, of course, one thing to call for respect of boundaries, as was
                     done in the Cairo Resolution or as is currently consecrated in
                     Article 4 (b) of the Constitutive Act of the AU ; but it is another thing
                      to determine where such dividing lines actually run. It is in the latter
                      case that a principle such as uti possidetis juris becomes relevant. Accord-
                      ing to the prevailing Latin American conception, uti possidetis juris is

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                     based on a dichotomy of title and effectivités, whereby title, if it is
                     found to exist, will trump the effectivités or the effective possession of the
                     territory 13.
                         26. The relationship between title and effectivités in the determination
                      of the boundary to be respected was never spelled out or even mentioned
                      in OAU or AU documents. In view of the above‑described diversity and
                      complexity of the process of independence of African States, the varied
                      legal régimes under which the delimitation of their boundaries was car-
                      ried out before independence (e.g., international treaties, administrative
                      boundaries, trusteeship agreements), and the sharply divided opinions
                      among African States at the time of independence, it appears that the
                      OAU/AU deliberately refrained from engaging in a detailed consider-
                      ation of legal issues, such as whether title to territory, possession or effec
                      tivités should prevail. Similarly, these organizations declined to lay down,
                      as part of the public law of Africa, a specific peaceful method applicable
                      to the settlement of all potential boundary disputes among all African
                      States, or to the determination of the course of such boundaries.

                        27. Instead, the Pan‑African organizations limited themselves to the
                     affirmation of a general and broad principle of respect of the boundaries
                     of member States in order to safeguard peace and stability in the conti-
                     nent. In other words, neither the Cairo Resolution nor the AU principles
                     have gone so far as the Spanish‑American States in defining a specific
                     method to be used to determine the course of African boundaries. This
                     does not, however, mean that African States cannot or have never had
                     recourse, in the settlement of bilateral disputes, to the use of uti posside
                     tis juris as a principle applicable to the delimitation of their boundaries or
                     as a method of ascertaining the pedigree of such boundaries. As clearly
                     indicated by the Judgments of the Court referred to above, they have
                     indeed done so and will most probably continue to do so in the future
                     particularly with respect to former administrative boundaries inherited
                     from the same colonial power.

                        13 “Where the act corresponds exactly to law, where effective administration is addi-

                     tional to the uti possidetis juris, 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
                     territory which is the subject of the dispute 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 effectivité 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 effectivités can then play an essential
                     role in showing how the title is interpreted in practice.” (Frontier Dispute (Burkina Faso/
                     Republic of Mali), Judgment, I.C.J. Reports 1986, pp. 586‑587, para. 63.)

                     102

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                                            3. Differences in Legal Nature
                        28. The two principles — uti possidetis juris and the OAU/AU princi-
                     ple on the respect of boundaries — also differ in their legal nature. First,
                     a distinction needs to be made between a broad principle which places
                     frontier disputes among African States in a “holding pattern” until a
                     peaceful solution is found between the parties concerned, and a specific
                     principle which embodies the criteria and methods for ascertaining the
                     pedigree of a boundary and for determining title to territory on the basis
                     of colonial legislation. Uti possidetis juris corresponds to the latter, while
                     the Cairo Resolution and Article 4 (b) of the Constitutive Act of the AU
                     lay down the former.
                        29. Secondly, the OAU/AU principle is specific to the African conti-
                     nent where it is considered as part of the public law of Africa applicable
                     to all African States, but has no claim to being a general principle or a
                     customary rule of international law. Conversely, uti possidetis juris has
                     been characterized as follows by the Chamber of the Court in Frontier
                     Dispute (Burkina Faso/Republic of Mali) :

                              “Nevertheless the principle is not a special rule which pertains
                           solely to one specific system of international law. It is a general prin-
                           ciple, which is logically connected with the phenomenon of the obtain-
                           ing of independence, wherever it occurs.” (Judgment, I.C.J. Reports
                           1986, p. 565, para. 20.)
                        30. The Chamber of the Court did not justify this sweeping statement
                     nor did it give clear reasons as to the source of this conclusion except to
                     say that, in addition to its Spanish‑American origins, uti possidetis juris
                     also found application and recognition in Africa. However, the alleged
                     acceptance of the principle by all African States appears to be based on
                     the assumption that the OAU principle established in the Cairo Resolu-
                     tion of 1964 was synonymous with or equivalent to uti possidetis juris.
                     Nevertheless, the Chamber later observed in the same Judgment that :

                           “[u]ti possidetis, as a principle which upgraded former administrative
                           delimitations, established during the colonial period, to international
                           frontiers, is therefore a principle of a general kind which is logically
                           connected with this form of decolonization wherever it occurs” (ibid.,
                           p. 566, para. 23).
                        31. The latter statement of the Chamber, which emphasizes the specific
                     role of uti possidetis juris with respect to former administrative boundar-
                     ies, appears, in my view, to correspond more to the actual practice of
                     States than the earlier conclusion characterizing uti possidetis as a general
                     principle applicable to all situations of decolonization. Even in the case of
                     African States, recourse to uti possidetis juris is generally for the purpose
                     of delimitation or demarcation of former administrative boundaries, as

                     103

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                     was the case in Frontier Dispute (Burkina Faso/Republic of Mali) or in
                     Frontier Dispute (Benin/Niger). Uti possidetis juris would indeed be
                     redundant in the case of disputes over boundaries delimited by an inter-
                     national treaty concluded either between two colonial powers or between
                     an African State and a colonial power or between two African States 14.

                        32. Thirdly, the principle of uti possidetis juris constitutes a method of
                     determining the course of a boundary on the basis of legal title, and offers
                     a criterion for ascertaining the pedigree of such a boundary. This is indeed
                     the main reason why it has become a very useful tool for the settlement of
                     boundary disputes in cases involving former administrative boundaries or
                     boundaries arising from the dissolution of a larger entity. The OAU/AU
                     principle on the respect of boundaries could not be of much help, nor was
                     it conceived to offer criteria, in the ascertainment of the pedigree of
                     boundary lines. It prescribes respect for, and prohibits assault on, the ter-
                     ritories of the OAU/AU member States as they existed at the time of
                     independence. Thus, as pointed out above, the relationship between title
                     and effectivités, or the need to give preference to one over the other, or
                     the manner in which such title should be determined, is neither explicitly
                     nor implicitly dealt with in the OAU/AU principle.

                        33. Moreover, to the extent that a key characteristic of Spanish‑Amer-
                     ican uti possidetis juris is that the borders existing at the time of indepen-
                     dence are to be determined by reference to the Spanish legislation of the
                     time, it is difficult, if not impossible, to ascribe a similar intention to “con-
                     secrate” the colonial law to the African States which adopted the Cairo
                     Resolution or the principles of the AU Constitutive Act. The rejection by
                     the OAU/AU of a rearrangement of borders on ethnic lines or on the
                     basis of historical and geographic claims does not amount to an accep-
                     tance of colonial law as title to territory. It was certainly not the intent of
                     the member States of the OAU or the AU to collectively ratify, through
                     the adoption of this principle, the General Act of Berlin of 1885 or to
                     recognize the administrative law of the colonial powers.

                                                                   *
                                                               *       *

                        14 In its Judgment in the case concerning the Territorial Dispute (Libyan Arab Jamahi

                     riya/Chad), the Court stated as follows :
                              “It will be evident from the preceding discussion that the dispute before the
                           Court . . . is conclusively determined by a Treaty to which Libya is an original party
                           and Chad a party in succession to France . . . Hence there is no need for the Court to
                           explore matters which have been discussed at length before it such as the principle of
                           uti possidetis and the applicability of the Declaration adopted by the Organization of
                           African Unity at Cairo in 1964.” (I.C.J. Reports 1994, p. 38, para. 75.)

                     104

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                        34. There is no doubt that the principle of uti possidetis juris has served,
                     over the years, many advantageous functions in Latin America, and con-
                     tinues to play a useful role in the settlement of boundary disputes in other
                     parts of the world. It cannot, however, be considered as a synonym of the
                     principle endorsed by the OAU in 1964, and later inscribed in the Consti-
                     tutive Act of the AU principle which deals with respect of the boundaries
                     of sovereign independent States in accordance with the United Nations
                     Charter and with the founding instruments of the OAU and AU.
                        35. The OAU member States, and later the AU, adopted the principle
                     of respect of boundaries existing on the achievement of independence out
                     of a sense of pragmatism in order to ward off conflict and chaos in the
                     African continent. It is an African principle which applies among all
                     member States of the Pan‑African organization and imposes upon them
                     the obligation to respect the boundaries existing at the time of indepen-
                     dence, pending the peaceful resolution of any border dispute which may
                     arise between them. It is in this context that it may be said that the
                     two principles share a similar rationale in so far as they both seek to
                     encourage recourse to the peaceful settlement of frontier disputes in con-
                     formity with international law.
                        36. The international legal principles to be applied for this purpose may,
                     of course, include the principle of uti possidetis juris. It has indeed hap-
                     pened in the past, and it may also happen in the future, that two African
                     States agree to have recourse to the application of the principle of uti pos
                     sidetis juris in a bilateral frontier dispute before the Court or before arbitral
                     tribunals. In such cases, the application of uti possidetis juris is based on a
                     bilateral understanding or agreement, but not on a general principle or cus-
                     tomary norm that has emerged as a result of the adoption of the 1964 Cairo
                     Resolution or of the Constitutive Act of the African Union.

                                   IV. The Principle of Territorial Integrity
                                           and Uti Possidetis Juris

                        37. The passage of the 1986 Judgment of the Chamber of the Court
                     quoted in paragraph 4 above also suggests that there was an indirect ref-
                     erence to uti possidetis in Article III, paragraph 3, of the OAU Charter.
                     As shown in paragraph 7 above, Article III, paragraph 3, of the OAU
                     Charter declared the adherence of its member States to the principle of
                     “respect for the sovereignty and territorial integrity of each State and for
                     its inalienable right to independent existence”. It is the reference to
                     “respect . . . for territorial integrity” that the Chamber of the Court
                     appears to have found to contain, in an implicit sense, an uti possidetis
                     principle applicable among all African States.
                        38. The OAU Charter was replaced by the AU Constitutive Act on
                     26 May 2001. Thus, Article III, paragraph 3, no longer exists. In its place,
                     one of the objectives of the Constitutive Act of the AU, as an instrument
                     of solidarity among African States, is to “defend the sovereignty, territo-

                     105

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                     146 	                frontier dispute (sep. op. yusuf)

                     rial integrity and independence of its Member States” (Art. 3, para. (b)).
                     Perhaps this evolution of the principle of territorial integrity in the consti-
                     tutive instruments of the Pan‑African organizations already sheds some
                     light on the distinction between uti possidetis juris and territorial integrity.
                     It may, however, still be useful to say a few words about the difference
                     between the two principles, particularly in the context of the founding
                     instruments of the OAU/AU.
                        39. It is erroneous, in my view, to read into the time‑hallowed principle
                     of respect for territorial integrity a reference to the principle of uti possi
                     detis juris or to assimilate these two distinct principles of international
                     law. If one reads an indirect reference to uti possidetis in Article III, para-
                     graph 3, of the OAU Charter because of its language on “territorial integ-
                     rity”, then the same conclusion must be reached concerning Article 2,
                     paragraph 4, of the United Nations Charter. The two Charters refer to
                     territorial integrity as a fundamental principle of international law and an
                     essential foundation of peaceful relations between States, but neither of
                     them deals with uti possidetis juris.

                        40. In so far as boundaries may be likened to the outer shell of the ter-
                     ritory of the State, it is the inviolability of those boundaries which is
                     implicit in the concept of territorial integrity. This is, however, quite dif-
                     ferent from uti possidetis juris as discussed in Section III above. Inviola-
                     bility bars the alteration of existing boundaries by force. It also implies
                     that such alteration, should it occur, is not capable of producing any legal
                     effect. This is clearly articulated in the 1970 United Nations Declaration
                     on Principles of International Law (General Assembly resolu-
                     tion 2625 (XXV)), according to which :

                             “Every State has the duty to refrain from the threat or use of force
                           to violate the existing international boundaries of another State or as
                           a means of solving international disputes, including territorial dis-
                           putes and problems concerning frontiers of States.”

                        41. The reference in the Cairo Resolution to Article III, paragraph 3,
                     of the OAU Charter, may be construed as a reference to the inviolability
                     of boundaries which is implicit in the principle of territorial integrity, but
                     cannot be taken to have “deliberately defined and stressed the principle of
                     uti possidetis juris contained only in an implicit sense in the Charter of
                     their organization”, as stated by the Chamber of the Court. In this, the
                     principle enunciated in the Cairo Resolution is similar to principle III on
                     the “Inviolability of frontiers” in the Final Act of the Conference on
                     Security and Co‑operation in Europe of 1975, according to which :

                              “The participating States regard as inviolable all one another’s
                           frontiers as well as the frontiers of all States in Europe and there-

                     106

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                           fore they will refrain now and in the future from assaulting those
                           frontiers.
                              Accordingly, they will also refrain from any demand for, or act of,
                           seizure and usurpation of part or all of the territory of any partici-
                           pating State.” 15
                        42. As formulated above, the principle of inviolability of boundaries
                     may be considered to constitute a basic element of the broader principle
                     of territorial integrity of States, and it was in the context of the relation-
                     ship of these two principles that the Cairo Resolution also referred back
                     to Article III, paragraph 3, of the OAU Charter. It should, however, be
                     noted that inviolability does not mean invariability or intangibility of
                     frontiers, in general. It means that any territorial changes are effected by
                     mutual consent, or through other means of peaceful settlement of dis-
                     putes, in conformity with international law.

                        43. The OAU/AU member States prescribed the principle of respect of
                     boundaries existing on achievement of independence, and implicitly rec-
                     ognized their inviolability in the sense discussed above, in order to ensure
                     peace and stability in the African continent in the same way that the Con-
                     ference on Security and Co‑operation in Europe adopted a similar prin-
                     ciple in 1975 to promote security in the European continent. Both
                     prescriptions derive their inspiration from the broader principle of terri-
                     torial integrity enshrined in the United Nations Charter. Neither of them
                     was directed, in my view, to define or stress the principle of uti possidetis
                     juris which has a different meaning and normative content.

                                                V. Concluding Remarks

                        44. Although the Parties — Burkina Faso and Niger — invoked the
                     principle of uti possidetis juris in their pleadings, this case is quite different
                     from the previous cases of Frontier Dispute (Burkina Faso/Republic of Mali)
                     (I.C.J. Reports 1986) and Frontier Dispute (Benin/Niger) (I.C.J. Reports
                     2005). In the present case, Burkina Faso and Niger concluded an agree-
                     ment in 1987 on the delimitation of their common boundary. They have
                     not, however, been able to agree, since that time, on the interpretation
                     and application of the agreement with respect to the actual course of the
                     boundary line. The dispute they have submitted to the Court concerns
                     this disagreement.

                       45. Unlike the previous delimitation cases mentioned above, this dis-
                     pute between the Parties, which concerns the interpretation and applica-

                        15 Organization for Security and Co‑operation in Europe, Final Act of the Conference

                     on Security and Co‑operation in Europe, 1 August 1975, 14 ILM 1292.

                     107

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                     148 	               frontier dispute (sep. op. yusuf)

                     tion of an international agreement, did not have to be appraised in the
                     light of French colonial law, or “droit d’outre‑mer”. In other words, the
                     Court was not required, in the present case, to determine what consti-
                     tuted for each of the Parties the colonial heritage to which the uti posside
                     tis was to apply. The Parties had already specified that in their own
                     delimitation agreement.
                        46. Thus, despite the fact that Burkina Faso and Niger inherited the
                     former administrative boundaries of French West Africa, which became
                     international boundaries upon their accession to independence, it is my
                     view that the principle of uti possidetis juris had become redundant in this
                     case as a result of the conclusion of the 1987 delimitation agreement
                     between the two independent States. The Court was asked to interpret
                     this delimitation agreement.
                        47. The Judgment should have clearly recognized that uti possidetis
                     juris and “droit d’outre‑mer” had no effective role to play in this case. A
                     statement similar to the one made by the Court in Territorial Dispute
                     (Libyan Arab Jamahiriya/Chad) (I.C.J. Reports 1994, p. 38, para. 75, and
                     cited at paragraph 31, footnote 14 above) could have been made in the
                     Judgment. The Court could also have seized this opportunity to clear up
                     the confusion between uti possidetis juris and the OAU/AU principle on
                     the respect of existing boundaries upon which the 1987 Agreement
                     between the Parties appears to be based.

                                                               (Signed) Abdulqawi A. Yusuf.

                     108

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