## Facts

- On 10 July 1985 French DGSE agents sabotaged and sank Greenpeace’s vessel *Rainbow Warrior* in Auckland Harbour, New Zealand, killing photographer Fernando Pereira.
- New Zealand arrested two French agents, Major Alain Mafart and Captain Dominique Prieur, who pleaded guilty (including to manslaughter and wilful damage) and received ten-year prison sentences.
- France and New Zealand asked the UN Secretary-General (Javier Pérez de Cuéllar) to resolve aspects of the dispute; on 6 July 1986 he issued a binding ruling requiring, among other measures, payment of US $7 million and the transfer of Mafart and Prieur to a French military facility on Hao Atoll (French Polynesia) for three years.
- By exchange of letters on 9 July 1986, the states concluded two agreements implementing the ruling, including a detention arrangement stating that the agents “will be prohibited from leaving the island for any reason, except with the mutual consent of the two Governments.”
- The agents were transferred to Hao on 23 July 1986.
- In December 1987, France sought New Zealand’s consent for an “urgent” medical transfer of Mafart; before New Zealand agreed, France evacuated him from Hao to France (14 December 1987) and refused New Zealand’s request to send a doctor to Hao via a New Zealand military aircraft.
- After treatment, France did not return Mafart to Hao and treated his situation as resolved without securing New Zealand’s agreement to any substitute arrangement.
- In 1988, France also removed Prieur from Hao to France on humanitarian grounds (including her father’s illness) without New Zealand’s prior consent and did not return her.
- The 9 July 1986 instruments provided for arbitration of disputes on interpretation or application that could not be settled diplomatically; a supplementary agreement in February 1989 addressed procedural matters.
- New Zealand commenced arbitration in 1989; an ad hoc France–New Zealand Arbitral Tribunal seated in New York issued its award on 30 April 1990.

## Issues

1. Whether the 9 July 1986 agreements required France to keep Mafart and Prieur on Hao for not less than three years and to permit any departure only with the mutual consent of both states, and whether France’s removals and non-return breached those obligations.
2. Whether France’s non-performance was excused by circumstances precluding wrongfulness under international law, especially force majeure or distress (and, if argued, necessity).
3. What legal consequences followed from any breach, including whether the tribunal should order return to Hao and what forms of reparation (declaration, satisfaction, assurances) were appropriate.

## Decision

- The tribunal held that the 9 July 1986 instruments were binding agreements governed by international law and had to be performed in good faith.
- The tribunal found France breached the agreements by removing Mafart and Prieur from Hao without New Zealand’s mutual consent and by failing to restore performance thereafter.
- The tribunal rejected force majeure as a justification because the events did not make performance materially impossible in the relevant sense and France’s conduct involved intentional decisions rather than unavoidable external compulsion.
- The tribunal accepted distress in principle as a possible excuse, but only under strict, exceptional conditions.
- As to Mafart, the tribunal held that an emergency medical evacuation could be temporarily excused by distress if the medical peril was extreme and urgent and if France acted in good faith toward New Zealand (including timely, full information and a real chance for verification and decision); however, France’s continued failure to restore the original detention arrangement once the emergency ended was not excused.
- As to Prieur, the tribunal held that the reasons advanced (humanitarian considerations linked to family circumstances) did not meet the threshold for distress as understood in international law; France’s removal was therefore not justified.
- On remedies, the tribunal declined to order return of the agents to Hao, giving weight to the fact that by the time of the award the three-year period set by the agreements had effectively run its course, making renewed detention an unsuitable form of restitution in the circumstances.
- The tribunal granted non-material reparation, including a formal declaration of breach and measures of satisfaction/assurances directed to repairing the injury caused by France’s failure to comply with the detention regime and with good-faith performance requirements.

## Legal Principles

- Treaty performance is governed by good faith; an implementing agreement concluded to carry out a mediated or third-party ruling remains a binding legal instrument between states.
- Where an agreement conditions departure from a detention or restriction regime on “mutual consent,” unilateral action is inconsistent with the obligation; consent must be sought and obtained before deviation, absent a valid excuse under international law.
- Good faith in seeking consent includes: providing full and timely information, not obstructing reasonable verification requests, and allowing the other party a genuine opportunity to make an informed decision.
- Force majeure is limited to unforeseen external events that make performance materially impossible; it does not cover deliberate policy choices or convenience-based departures from agreed conduct.
- Distress may preclude wrongfulness only in very exceptional situations of extreme peril where the state organ has no other reasonable way to safeguard life or health; any excuse is limited in time and linked to restoring compliance once the peril passes.
- When a breach is established, international responsibility entails cessation (where relevant) and reparation; where restitution is no longer suitable, a tribunal may grant declaratory relief and satisfaction as appropriate forms of reparation.

## Conclusion

The *Rainbow Warrior* arbitration held that France violated the 9 July 1986 agreements requiring Mafart and Prieur to remain on Hao unless both governments consented to a departure. The tribunal rejected force majeure, treated distress as a narrow, exceptional excuse that could at most justify a brief medical evacuation for Mafart, and held it did not justify Prieur’s transfer. Because the agreed three-year term had effectively expired by the time of decision, the tribunal refused to order return to Hao and instead awarded a declaration of breach and satisfaction-type relief reflecting France’s international responsibility.


Rainbow Warrior (New Zealand v. France), 82 I.L.R. 499 (Fr.–N.Z. Arb. Trib. 1990)