## Facts

- Nicaragua and Colombia disputed territorial sovereignty over maritime features in the western Caribbean near the San Andrés Archipelago and the delimitation of maritime zones (territorial sea, EEZ, and continental shelf).
- A 1928 treaty and 1930 protocol recognized Colombia’s sovereignty over San Andrés, Providencia, and Santa Catalina, while recognizing Nicaragua’s sovereignty over the Mosquito Coast and Corn Islands.
- Nicaragua later challenged the treaty’s validity and argued it did not settle maritime delimitation or clearly define the archipelago’s full composition.
- The archipelago’s principal islands are administered by Colombia but lie closer to Nicaragua’s mainland than to Colombia’s mainland.
- Nicaragua instituted proceedings in 2001, invoking the Pact of Bogotá and related jurisdictional instruments.
- In 2007, the Court held it lacked jurisdiction over sovereignty disputes concerning San Andrés, Providencia, and Santa Catalina (no extant dispute), but retained jurisdiction over sovereignty of other cays/banks and maritime delimitation.
- Nicaragua also sought delimitation of a continental shelf beyond 200 nautical miles from its coast, potentially overlapping with Colombia’s entitlements.

## Issues

1. Whether the 1928 treaty was valid and, if so, what sovereignty questions it resolved and what questions remained open regarding other cays and banks.
2. Which State had sovereignty over specific disputed maritime features beyond the principal islands.
3. Whether Nicaragua’s claim to a continental shelf beyond 200 nautical miles was admissible and sufficiently supported to permit delimitation.
4. How to delimit the territorial sea, EEZ, and continental shelf (within 200 nautical miles) between Nicaragua and Colombia, including the effect to be given to Colombian islands and cays.

## Decision

- The Court treated Colombia’s sovereignty over San Andrés, Providencia, and Santa Catalina as settled and not subject to merits determination in this phase.
- The Court determined sovereignty over the remaining disputed cays and banks by treaty interpretation where possible and, where the treaty did not settle title, by assessing effectivités (peaceful, public, and consistent displays of authority).
- The Court did not delimit a continental shelf beyond 200 nautical miles, finding Nicaragua had not provided sufficient scientific/technical material to enable delimitation in the case as presented.
- For maritime delimitation within 200 nautical miles, the Court applied an equidistance/relevant circumstances approach and adjusted the line to avoid inequitable cut-off effects from Nicaragua’s coastal configuration.
- The Court limited the maritime effect of Colombia’s islands and cays by enclaving or semi-enclaving them, generally using 12-nautical-mile arcs, while allocating substantial EEZ/continental shelf areas to Nicaragua to the east of its mainland.

## Legal Principles

- Treaty-based territorial title prevails over inconsistent effectivités; where treaty language does not resolve title, effectivités may determine sovereignty.
- Maritime delimitation between opposite coasts commonly proceeds by: (1) drawing a provisional equidistance line, (2) adjusting for relevant circumstances to reach an equitable result, and (3) confirming the result by a disproportionality check.
- Relevant circumstances may include coastal concavity producing cut-off effects and the presence of small islands whose full effect would distort an equitable delimitation.
- A claim to a continental shelf beyond 200 nautical miles is not barred in principle, but delimitation requires sufficiently specific and supported evidence of the outer limits and the overlap area.

## Conclusion

The Court upheld Colombia’s sovereignty over the principal islands, resolved sovereignty over additional maritime features through treaty interpretation and effectivités, drew an adjusted maritime boundary that granted Nicaragua extensive EEZ and continental shelf areas while limiting the effect of Colombian islands through enclaves, and declined to delimit any extended continental shelf beyond 200 nautical miles due to insufficient evidentiary support.


Territorial and Maritime Dispute (Nicar. v. Colom.), 2012 I.C.J. Rep. 624 (2012)