The 1977/78 Anglo-French Channel arbitration

The delimitation of the continental shelf in the English Channel and its
western approaches in the Atlantic area posed problems during negotiations
preceding this landmark arbitration for two reasons. Firstly, the
English Channel Islands, under British sovereignty for purposes of foreign
relations, consist of an archipelagic formation of four main groups
with the principle islands of Alderney, Guernsey, Jersey, Sark, Herm and
Jethon. The islands are situated off the coast of France, the closest, the
island of Ecrehos, being only 6.6 miles from the continent. Geologically,
the islands are both linked to the English mainland by a basic continuity
of the shelf, and also separated from it by a the trough of Hurd Deep, a
trench of some 100 metres running a few miles north of the islands in
south-westerly direction for some 80 miles. Secondly, in the western part
(or the western approaches or Atlantic area), both states show atypical
coastal configurations in the sense that they are neither in a clearly
opposite nor in a clearly adjacent constellation. Moreover, both parties
have islands: the Scilly Isles off the Cornish coast and the island of Ushant
(Quessant) off the Brest peninsula. As possible base points, both groups
of islands could strongly influence the direction of the western boundary
extending into the Atlantic Ocean.
Negotiations between France and the United Kingdom took place
between 1970 and 1974 and reached a partial agreement. However,
they failed to settle a boundary in the area 30 minutes west of the
Greenwich meridian as far as the 1,000 metre isobath in the Atlantic
region. The case was submitted by Special Agreement to a Court of
Arbitration. Unlike in the North Sea cases, these parties asked for a final
delimitation of the continental shelf boundary.
Britain argued that the Channel Islands are to be taken into full account
under Article 6 of the 1958 Shelf Convention and that the requirements for
considering special circumstances were not met. The Islands’ entitlement
to a shelf was stressed, in accordance with Article 1(b) of the Convention.
The United Kingdom further claimed a strict median line fully embracing
the islands in a deep loop towards the French coast, linking the shelf of the
islands with that of the English mainland. France, on the other hand,
argued that the islands should be completely ignored when drawing a
median line in the Channel. Instead, the line should be measured from
the French and English coasts. With regard to the south-western
approaches (or the Atlantic area), the United Kingdom argued that the
two coasts were opposite, and that no proof existed to justify the use of
special circumstances to depart from the median line. Full effect should be
given to both the Scilly Islands and the Island of Ushant, leaving the result
similar to that under customary law. The United Kingdom went on to
assert that if the median line were to be departed from, this could only be
done by relying on the natural boundary of the Hurd Deep Fault Zone, a
continuation of the Hurd Deep to the south-west and south of the median
France, on the other side, proposed a median line consisting of a line
bisecting the general directions of the coastlines of the English and
the French coasts (lignes de lissages). It argued that neither paragraph 1
nor 2 of Article 6 of the 1958 Shelf Convention would apply, as the
situation is neither one of opposite nor adjacent coasts in the Atlantic
In making its decision, the Court of Arbitration essentially adopted the
French position. Relying upon the doctrine set forth by the North Sea
cases, the Court applied the model of equity and equitable principles. It
declined to apply the rule of equidistance–special circumstance of Article
6 of the 1958 Shelf Convention due to a French reservation made at its
accession to the agreement. The Court drew a median line without taking
into account the Channel Islands, but granted them a 12-mile territorial
sea toward the median line, leaving undefined the extension of that zone
toward the French coast.
In the Atlantic area, the Court adopted its own proposition of giving
half-effect to both the Scilly Isles and Ushant. It drew a straight boundary
line roughly in the middle of the lines as proposed by the two parties
to the dispute. An additional award in March 1978 completed and
clarified the base points from which the territorial sea of the Channel
Islands has to be measured.
A British petition to modify the straight loxodrome boundary line in
the Atlantic into a geodesic line was declined. The disputed line had
been drawn by the technical experts of the Court on the basis of a
mercator navigational chart by means of plane geometry. This resulted
in distortions of approximately 4 miles at the 1,000 meter isobath and
several miles at the 200-mile limit, at the expense of the United
Kingdom’s shelf