Due Diligence in the International Law of Aliens: Conceptual Framework
In the law of aliens, due diligence is closely related to the concept of fault. Responsibility for fault or due diligence represents a middle path between the national community’s collective responsibility for acts of its individual members and the exclusion of state responsibility for acts of individuals. The role of fault in state responsibility dominated centuries of scholarly debate. As international law excluded fault from the elements of the internationally wrongful act, the primary obligation to protect foreigners was defined in terms of due diligence. Due diligence thus appears as a functional equivalent to the notion of fault. In this system, the host state is not indirectly responsible for acts of individuals, but directly responsible for its own omissions in the protection of aliens.