## Facts

- Guyana and Suriname are adjacent coastal States on the northeast coast of South America and parties to the United Nations Convention on the Law of the Sea (UNCLOS).
- A 1936 British–Dutch Mixed Boundary Commission fixed the northern end of the land boundary at Point 61 on the west bank of the Corentyne River; the colonial powers also agreed that the territorial sea boundary would follow an azimuth of N 10° E from Point 61 out to 3 nautical miles (the “10° line”).
- After independence, the States extended their territorial seas to 12 nautical miles and disputed whether the maritime boundary should continue along the 10° line (Suriname) or follow an equidistance-based approach for the continental shelf and exclusive economic zone (EEZ) (Guyana).
- The disputed maritime area was substantial and considered prospective for hydrocarbons.
- Guyana granted an offshore concession to CGX (a Canadian company) in the disputed area; CGX undertook seismic work and moved to drilling.
- On June 3, 2000, Surinamese naval vessels confronted CGX’s drilling unit and support vessels, ordering them to leave and warning that noncompliance would have consequences; CGX withdrew and Guyana protested.
- Guyana initiated UNCLOS Annex VII arbitration in 2004 seeking (1) maritime delimitation and (2) findings that Suriname’s conduct breached UNCLOS and general international law.
- The tribunal constituted under UNCLOS Annex VII asserted jurisdiction under UNCLOS compulsory procedures and applied other compatible rules of international law through UNCLOS Article 293.

## Issues

1. What is the proper single maritime boundary between Guyana and Suriname for the territorial sea, continental shelf, and EEZ, including whether the 10° line governs beyond 3 nautical miles.
2. Whether Suriname’s June 3, 2000 naval actions against CGX constituted unlawful interference with Guyana’s UNCLOS rights and/or an unlawful threat of force under the U.N. Charter and general international law, and what restraint obligations apply pending delimitation.

## Decision

- The tribunal delimited a single maritime boundary for the territorial sea, continental shelf, and EEZ.
- It rejected Suriname’s claim that the 10° line continues as the boundary beyond the original 3-nautical-mile territorial sea.
- For the territorial sea, it accepted a limited deviation from strict equidistance near the Corentyne River mouth based on a special navigational circumstance tied to historical arrangements.
- For the continental shelf and EEZ, it applied a provisional equidistance line, found no relevant circumstances requiring adjustment, and confirmed the resulting line was equitable.
- It held Suriname’s conduct in the CGX incident amounted to an unlawful threat of force contrary to the U.N. Charter and general international law as applied via UNCLOS Article 293.
- It found Guyana acted inconsistently with obligations of mutual restraint and cooperation by authorizing drilling in a disputed area, but the principal breach found was Suriname’s threat of force.
- It did not award monetary compensation; the dispositive relief was delimitation and declarations regarding conduct.

## Legal Principles

- UNCLOS Annex VII tribunals have jurisdiction over disputes concerning the interpretation or application of UNCLOS, including maritime boundary delimitation; UNCLOS Article 293 permits application of compatible rules of general international law.
- Territorial sea delimitation under UNCLOS Article 15 gives primacy to a median line absent agreement, subject to historic title or other special circumstances; special circumstances are assessed case by case.
- Delimitation of the continental shelf and EEZ generally proceeds by drawing a provisional equidistance line, considering relevant circumstances for adjustment to reach an equitable result, and applying a disproportionality check.
- Unilateral oil concessions and existing wells are generally irrelevant to delimitation absent an agreement between the States.
- In disputed maritime areas, States must act with restraint and seek cooperative provisional arrangements; unilateral acts that risk jeopardizing or hampering agreement may breach these obligations.
- Coercive deployment of armed naval vessels coupled with threatening language to expel activities from a disputed area can constitute an unlawful threat of force under Article 2(4) of the U.N. Charter.

## Conclusion

The tribunal established a single Guyana–Suriname maritime boundary by using equidistance for the continental shelf and EEZ and a limited special-circumstance adjustment in the territorial sea, rejected extension of the historic 10° line, and declared Suriname’s armed confrontation with the CGX operation an unlawful threat of force while also faulting Guyana for insufficient restraint in authorizing drilling in the disputed area.


Guyana v. Suriname, 47 I.L.M. 166 (Annex VII Arb. Trib. 2008)