Excusing Unlawful Use of Force Under the Law of State Responsibility

Abstract

No justification for the use of force exists under international law, other than Security Council authorisation and self-defence. Creative readings of the UN Charter’s provisions on the use of force are problematic from the aspect of legal doctrine and potentially dangerous in (state) practice. However, same practice exists where states and UN organs have accepted certain consequences of an illegal use of force on humanitarian grounds. Breaching the underlying prohibition was seen as the choice of a ‘lesser evil’. Governments and scholars have commonly categorised such instances as sui generis and carved the phrase ‘illegal but legitimate’. This article captures such sui generis ‘illegal but legitimate’ practice within the conceptual framework of international law. It proposes that a distinction between justifications and excuses should be introduced to international law, whereas justifications preclude wrongfulness of an act, while excuses merely mitigate against responsibility for wrongfulness. In the context of the use of force, Security Council’s authorisation and self-defence are justifications under primary norms. When requirements for lawful use of force are not met, the unlawfulness could be excused (but not justified) under the secondary rules of state responsibility. This solution preserves the strength of the primary prohibition of the use of force, and accommodates humanitarian intervention without the Security Council’s authorisation within the law of state responsibility. Such a conceptualisation, however, also requires critical engagement with the ILC Articles on State Responsibility.