Benin–Niger border

Two French colonies

France set up the colony of Benin in 1893, renamed it Dahomey the next year, and made it part of French West Africa in 1899. Niger began as a military territory at the end of 1900 and became a colony in 1922. Dahomey became independent on 1 August 1960 and Niger on 3 August 1960; Dahomey is now Benin.^[1]

The line comes from a French statute of 27 October 1938 describing the northern edge of Dahomey’s Kandi district: along the Niger, then up the Mekrou. In 1973 the US Geographer noted that nothing said whether the line followed the rivers’ main channels or their middles, or who owned the islands in them.^[1]

The islands case

Benin and Niger took the question to the International Court of Justice together on 3 May 2002. Benin argued the border followed the Niger’s left bank, which would give it every island; Niger argued it followed the deepest channel, so each island belonged to whichever side it lay on. The biggest island in dispute was Lété.^[2]

The chamber found that neither side’s colonial documents proved its case, so it looked at who had actually governed. A letter of 3 July 1914 from the French officer at Gaya, in Niger, listed the islands by which side of the main navigable channel they lay on, to settle grazing permits and courts, and local officials followed it until 1954.^[2]

On 12 July 2005 the chamber ruled, by four votes to one, that the border follows the main navigable channel of the Niger as it was at independence, except that it passes left of three islands opposite Gaya, which go to Benin. Lété went to Niger. The border on the bridges between Gaya and Malanville follows the river line, and the Mekrou border runs down the middle of that river, the last point decided unanimously.^[2]