Can occupation resulting from a war of self-defense become illegal ?
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Minnesota journal of international law, Vol. 24, issue 2, p. 313-350
Illegal occupation gives rise to a duty of the occupant to withdraw from the occupied territory immediately and unconditionally. International law has long recognized the illegality of occupation that results from an unlawful use of force by the occupying state. An emerging approach among international lawyers holds that occupation resulting from a lawful use of force by a state, in self-defense, may also become illegal. This article argues that the purview of the notion of illegal occupation in international law does not extend to occupation resulting from the lawful use of force by a state in self-defense ("lawfully created occupation"). The article reviews the various theories presented in support of such an extension, but shows that state practice does not support the existence of a rule of customary international law providing that a lawfully created occupation may subsequently become illegal. The author subscribes to the view that a policy of de facto annexation pursued by an occupant violates the right to self-determination, and possibly the prohibition on the use of force. Such violation leads to legal consequences, but these do not include the illegality of occupation. This article examines the rules of international law that determine the legal consequences of state conduct that violates international law, and shows that these rules do not accommodate an extension of the notion of illegal occupation to lawfully created occupation. The article proceeds to argue that the introduction of a rule of customary international law providing that a lawfully created occupation may subsequently become illegal is inadvisable because such a norm would be full of uncertainty.