Riccardo Pisillo-Mazzeschi (1992), 'The Due Diligence Rule and the Nature of the International Responsibility of States'

One of the most controversial problems regarding the international responsibility of the State for wrongful acts (hereinafter "State responsibility")l concerns the nature of such responsibility. One asks whether State responsibility in principle is contingent upon the existence of fault or, vice versa, upon the sole existence of conduct attributable to the State and contrary to an international obligation. In the first case we would have in general international law a unitary regime of fault responsibility, and in the second case a unitary regime of objective responsibility. It is also possible to say that in general international law different regimes of responsibiIity ex ist, depending on the various categories of wrongful acts or of rules or of obligations.