## Facts

- France and the United Kingdom disputed sovereignty over two groups of islets and rocks in the English Channel: the Minquiers and the Ecrehos, located between Jersey and the French coast.
- Both States asserted historic title traceable to the medieval period after the 1066 union between England and Normandy and the 1204 separation when France gained continental Normandy but did not occupy the Channel Islands.
- Medieval treaties and feudal-era materials invoked by both parties did not identify the specific islets and rocks at issue.
- By Special Agreement (1950; ratified 1951), the parties asked the ICJ to determine whether sovereignty over the islets and rocks (so far as capable of appropriation) belonged to the U.K. or France; the Court’s mandate did not allow a finding of terra nullius, condominium, or third-state sovereignty.
- The U.K. relied on an asserted ancient title supported by long-standing administrative, judicial, and regulatory acts connected to Jersey, including local records and court proceedings tied to the islets.
- France relied on original title and subsequent acts and argued that the 1839 Fisheries Convention limited the ability to treat later conduct as sovereign acts opposable to the other party.

## Issues

1. Whether sovereignty over the Minquiers and Ecrehos groups (to the extent capable of appropriation) belonged to the United Kingdom or to France.
2. How much weight to give to medieval titles and treaties that did not specify the individual islets and rocks.
3. Whether, and how, later “effectivités” (administration, legislation, policing, adjudication, and records) should determine sovereignty between competing claimants.
4. Whether the 1839 Fisheries Convention prevented reliance on post-convention acts as evidence of sovereignty.

## Decision

- The ICJ unanimously held that sovereignty over the islets and rocks of both the Ecrehos and Minquiers groups (so far as capable of appropriation) belonged to the United Kingdom.
- The Court treated medieval titles and treaties as inconclusive because they did not specify the particular islets.
- The Court relied chiefly on direct evidence of possession and the actual exercise of sovereign authority, finding the U.K.’s proof of administrative and judicial control connected to Jersey more persuasive.
- The Court rejected the argument that the 1839 Fisheries Convention neutralized later effectivités for purposes of territorial title.

## Legal Principles

- Where alleged historic title is uncertain or does not clearly cover the specific territory, sovereignty may turn on effectivités: a continuous, peaceful, and public display of state authority assessed comparatively between claimants.
- Treaties and historical instruments that do not identify the territory with sufficient specificity may have limited probative value in allocating sovereignty over small features.
- Regulatory, administrative, judicial, and archival evidence attributable to state authorities can constitute probative effectivités for territorial sovereignty.
- An agreement regulating shared economic activity (such as fisheries) does not, without clear terms, alter territorial sovereignty or render subsequent sovereign acts legally irrelevant.
- Under a compromis, the court applies the parties’ defined choices and allocates sovereignty to one party based on the more convincing proof on the record.

## Conclusion

The ICJ awarded sovereignty over the Minquiers and Ecrehos to the United Kingdom because medieval materials did not resolve title to the specific islets, and the United Kingdom demonstrated stronger, sustained effectivités through Jersey’s administration and jurisdiction, while France’s evidence was comparatively limited and less clearly sovereign in character.


Minquiers & Ecrehos (Fr. v. U.K.), 1953 I.C.J. 47 (Nov. 17)