The study examines possible defences that States could invoke in order to justify or excuse measures designed to respond to the COVID-19 crisis, which prima facie might not be in conformity with certain international obligations. The study examines only defences available in general international law – beside certain exceptions that might be provided by the clauses of the respective treaties. Two grounds for suspending international obligations, stemming from the law of treaties – impossibility of performance and rebus sic stantibus – and three circumstances precluding wrongfulness, stemming from the law of international responsibility – force majeure, distress and state of necessity – are subject to examination. The study argues that, even if “common sense” might draw the public opinion towards the plausibility of invoking force majeure, impossibility of performance or fundamental change of circumstances, such a conclusion does not reflect general international law. In reality, the “best candidate” as a justification or excuse is distress, while the “second best candidate” might be represented by the state of necessity.
