Blocking the Spread of Cross-Retaliation: the Exceptio Non Adimpleti Contractus in International Law

In the Application of the Interim Accord case on which the ICJ rendered its judgment in 2011, Judge Simma stated in his separate opinion that the exceptio non adimpleti contractus did not survive in international law. In the Diversion of Water from the Meuse case of 1937, however, Judge Hudson in his individual opinion emphasized that a tribunal bound by international law ought not to shrink from applying the exceptio as a general principle of law. While the exceptio could already be covered by countermeasures, temporary non-performance of an unrelated obligation could also be justified as a countermeasure. Where an alleged victim State steps outside the bounds of the synallagmatic treaty in question and takes measures of cross-retaliation in some other field, the situation may well be aggravated rather than settled. Analyzing the exceptio in the civil law as well as analogous principles in the common law, jurisprudence of international courts and tribunals, and the work of the ILC, it is argued that as long as the exceptio is available to the injured State, it has a right of place in international law as a bar to cross-retaliation.