Author: Iliya Rachkov
Keywords: error as a cause of invalidity of treaties; estoppel; International Court of Justice; international treaties; sovereignty; state borders
This article analyzes the resolution by the International Court of Justice of the long dispute between Cambodia and Thailand about ownership of the temple of Preah Vihear and areas in its vicinity. Uncertainty in this matter had resulted in armed clashes between the two States. The International Court of Justice addressed this dispute several times: in 1959–1962 and in 2011–2013. Under the Treaty of 1904, the boundary between then Siam (now Thailand) and French Indochina (now Cambodia) in the area of the temple of Preah Vihear in the Dângrêk Mountains tracked the watershed line. If we follow this line, the temple is situated on the Siamese side of the watershed. The delimitation of the boundary on the basis of this principle was entrusted to a mixed Franco-Siamese Commission. The Commission met for the last time in 1907 but never finished its work. However, Siam ordered French cartographers to make maps of the area. The maps were compiled and published in 1907 showing the border running north of the temple of Preah Vihear, thus leaving the temple in Cambodia. After receiving these maps, Thailand did not object to them and used them. Thus Thailand acquiesced to the correctness of the maps and by virtue of the principle of estoppel lost the right to challenge it, according to a decision by the International Court of Justice in 1962. Subsequently, the principle of estoppel has been repeatedly applied by the Court in other cases. In addition, the Court formulated rules on the invalidity of an international Treaty by virtue of error. In 1969 these rules were codified. Finally, in 2013, the ICJ gave an interpretation of its decision of 1962, as the debate about what land “near the Church” should be considered Cambodian never stopped. The interpretation of its own decisions is a tool rarely used by the Court. Unfortunately, the Court left unresolved the fate of Phnom Trap Mountain and the area around it.
About the author: Ilya V. Rachkov – Candidate of Sciences (PhD) in Law, LL.M, Associate Professor of the International Law Faculty of MGIMO (University).