Frontier Dispute (Benin/Niger)

On 3 May 2002, Benin and Niger, by joint notification of a Special Agreement signed on 15 June 2001 at Cotonou and which entered into force on 11 April 2002, seised the Court of a dispute concerning “the definitive delimitation of the whole boundary between them”. Under the terms of Article 1 of that Special Agreement, the Parties agreed to submit their frontier dispute to a Chamber of the Court, formed pursuant to Article 26, paragraph 2, of the Statute, and each to choose a judge ad hoc. By an Order of 27 November 2002, the Court unanimously decided to accede to the request of the two Parties for a special Chamber of five judges to be formed to deal with the case.

Following public hearings held in March 2005, the Chamber delivered its Judgment on 12 July 2005. After briefly recalling the geographical and historical context of the dispute between these two former colonies, which had been part of French West Africa (FWA) until their accession to independence in August 1960, the Chamber considered the question of the law applicable to the dispute. It stated that this included the principle of the intangibility of the boundaries inherited from colonization, or the principle of uti possidetis juris, whose “primary aim is . . . securing respect for the territorial boundaries at the moment when independence is achieved”. The Chamber found that, on the basis of this principle, it had to determine in the case the boundary that had been inherited from the French administration. It noted that “the Parties agreed that the dates to be taken into account for this purpose were those of their respective independence, namely 1 and 3 August 1960”.

The Chamber then considered the course of the boundary in the River Niger sector. It first examined the various regulative or administrative acts invoked by the Parties in support of their respective claims and concluded that “neither of the Parties has succeeded in providing evidence of title on the basis of [those] acts during the colonial period”. In accordance with the principle that, where no legal title exists, the effectivités “must invariably be taken into consideration”, the Chamber then proceeded to examine the evidence presented by the Parties regarding the effective exercise of authority on the ground during the colonial period, in order to determine the course of the boundary in the River Niger sector and to indicate to which of the two States each of the islands in the river belonged, in particular the island of Lété.

At the end of that examination, the Chamber concluded that the boundary between Benin and Niger in that sector follows the main navigable channel of the River Niger as it existed at the dates of independence, it being understood that, in the vicinity of the three islands opposite Gaya, the boundary passed to the left of those islands. Consequently, Benin had title to the islands situated between the boundary thus defined and the right bank of the river and Niger had title to the islands between that boundary and the left bank of the river.

In order to determine the precise location of the boundary line in the main navigable channel, namely the line of deepest soundings, as it existed at the dates of independence, the Chamber relied on a report prepared in 1970, at the request of the Governments of Dahomey (the former name of Benin), Mali, Niger and Nigeria, by the firm Netherlands Engineering Consultants (NEDECO). In its Judgment, the Chamber specified the co-ordinates of 154 points through which the boundary between Benin and Niger passes in that sector. It stated, inter alia, that Lété Goungou belongs to Niger. Finally, the Chamber concluded that the Special Agreement also conferred jurisdiction upon it to determine the boundary line on the bridges between Gaya and Malanville. It found that the boundary on those structures follows the course of the boundary in the River Niger.

In the second part of its Judgment, dealing with the western section of the boundary between Benin and Niger, in the sector of the River Mekrou, the Chamber proceeded to examine the various documents invoked by the Parties in support of their respective arguments. It concluded that, notwithstanding the existence of a legal title of 1907 relied on by Niger in support of its claimed boundary, it was clear that,

“at least from 1927 onwards, the competent administrative authorities regarded the course of the Mekrou as the intercolonial boundary separating Dahomey from Niger, that those authorities reflected that boundary in the successive instruments promulgated by them after 1927, some of which expressly indicated that boundary, whilst others necessarily implied it, and that this was the state of the law at the dates of independence in August 1960”.

The Chamber concluded that, in the River Mekrou sector, the boundary between Benin and Niger was constituted by the median line of that river.