The Rainbow Warrior, a Greenpeace vessel, was blown up in New Zealand by French secret service agents July 1985, a Netherlands citizen was killed; it was leaving to protest against French nuclear test in the Pacific. Two agents, Alain Marfat and Dominique Prieur were sentenced to 10 years in prison in NZ.
Following negotiations. UNSG issued an arbitral award July 1986: France should formally apologize for the breach and pay US$7 million to New Zealand; the secret agents were transferred to France who was to custody them for 3 years (1987-1989) in an isolated island. It was prohibited to leave the island except for mutual consent of the governments
Rainbow Warrior Arbitration involved the failure of France to detain the agents on the French Pacific island of Hao, as required by an agreement between France and New Zealand after the award of the Rainbow Warrior incident. Mafart had an abdominal problem, Dominique was 6 weeks pregnant, and her father was dying of cancer
New Zealand argued that the law of treaties primarily governed issues of the performance of a treaty, and that the law of State responsibility had a merely supplementary role. New Zealand claimed that the only excuses for failure to comply with a treaty obligation were those contained in the Vienna Convention on the Law of Treaties (e.g. impossibility of performance, fundamental change of circumstances).
The Tribunal held that both the law of treaties and the law of State responsibility had to be applied, the former to determine whether the treaty was still in force, the latter to determine what the consequences were of any breach of the treaty while it was in force (including the question whether the wrongfulness of any apparent breach was precluded): ‘the legal consequences of a breach of a treaty, including the determination of the circumstances that may exclude wrongfulness ... and the appropriate remedies for breach, are subjects that belong to the customary law of State responsibility. The reason is that the general principles of international law concerning State responsibility are equally applicable in the case of breach of treaty obligation, since in the international law field there is no distinction between contractual and tortious responsibility, so that any violation by a State of any obligation, of whatever origin, gives rise to State responsibility and, consequently, to the duty of reparation. The particular treaty itself might of course limit or extend the general law of State responsibility, for instance by establishing a system of remedies for it’