## Facts

- Guinea-Bissau and Senegal had a long-running dispute over maritime delimitation following independence.
- Senegal relied on a 1960 exchange of letters between France and Portugal that set a maritime boundary; Guinea-Bissau contested that instrument’s binding effect as between the two successor States.
- In 1985, the States concluded an arbitration agreement submitting two questions: (1) whether the 1960 instrument had force of law between them; and (2) if not, what boundary line delimited their maritime areas.
- The arbitration agreement contemplated that the decision would include drawing the boundary line on a map and that the award would be binding.
- On July 31, 1989, a three-member tribunal issued an award; two arbitrators voted for the text, and the presiding arbitrator appended a declaration.
- Guinea-Bissau instituted proceedings before the International Court of Justice (ICJ) in August 1989, seeking a declaration that the purported award was either legally non-existent or, alternatively, null and void.
- Guinea-Bissau argued the award was non-existent because the presiding arbitrator’s declaration allegedly contradicted the vote, and null because the tribunal failed to answer the second question, failed to draw a boundary line on a map, and failed to give reasons for declining to exercise jurisdiction on delimitation.
- Senegal contended the award was properly made and remained valid and binding.
- The case proceeded on the basis of both States’ declarations accepting the Court’s compulsory jurisdiction; Senegal invoked a temporal reservation limiting its acceptance to disputes arising after its declaration.

## Issues

1. Whether the ICJ had jurisdiction under the parties’ optional-clause declarations, given Senegal’s temporal reservation.
2. Whether Guinea-Bissau’s application was admissible as a challenge to the award’s existence and validity rather than an attempt to relitigate maritime delimitation.
3. Whether the arbitral award was legally “non-existent” due to an alleged lack of a genuine majority vote.
4. Whether the award was null and void because the tribunal failed to comply with the arbitration agreement by not addressing the second question, not drawing a boundary line on a map, or not stating adequate reasons.

## Decision

- The ICJ held it had jurisdiction because the dispute before it concerned the award’s existence and validity and arose only after the award was rendered, bringing it within Senegal’s temporal reservation.
- The ICJ found the application admissible because it raised a distinct legal dispute about the award, not the merits of delimitation.
- The ICJ rejected the claim of “inexistence,” holding the award was adopted by the required majority notwithstanding the presiding arbitrator’s separate declaration.
- The ICJ upheld the award as valid and binding on both States and rejected all submissions seeking declarations of inexistence or nullity.

## Legal Principles

- A temporal reservation to optional-clause jurisdiction may not bar jurisdiction where the dispute submitted is distinct from an earlier underlying controversy and arises after the declaration.
- An arbitral award exists as a legal act when duly adopted by the required majority; separate or dissenting declarations typically concern reasoning and do not negate the existence of the decision.
- Where an arbitration agreement frames questions conditionally, the tribunal’s duty to decide subsequent questions depends on the condition being met.
- Alleged deficiencies such as not addressing a conditional question, not producing a new map-based depiction of a line, or asserted inadequacy of reasons do not nullify an award absent a fundamental departure from the tribunal’s mandate or essential procedural requirements.
- Judicial review of an international arbitral award is limited to existence and validity defects and does not extend to reconsideration of the merits of the tribunal’s determinations.

## Conclusion

The ICJ treated the validity challenge as a new post-award dispute within its compulsory jurisdiction, confirmed that the award existed as a majority decision, and held that the tribunal’s handling of the conditional questions and related formal objections did not amount to a defect warranting annulment; the award remained binding on Guinea-Bissau and Senegal.


Case Concerning the Arbitral Award of 31 July 1989 (Guinea-Bissau v. Senegal), 1991 I.C.J. Rep. 53 (Nov. 12)