Principle of the Exclusive Jurisdiction of the Flag State in the law of the sea and customary international law

The flag State, namely, the State which has granted a ship the right to sail under its flag, has
the exclusive jurisdiction over vessels flying its flag. This is called the principle of the
exclusive jurisdiction of the flag State. The principle is well established in customary
international law. Article 92(1) of the LOSC formulates it as follows.
Ships shall sail under the flag of one State only and, save in exceptional cases expressly
provided for in international treaties or in this Convention, shall be subject to its exclusive
jurisdiction on the high seas.
The flag State jurisdiction comprises both legislative and enforcement jurisdiction over its
ships on the high seas. The flag State exercises enforcement jurisdiction over all peoples
within its ships flying its flag regardless of their nationalities. In this regard, ITLOS stated:

The ship, everything on it, and every person involved or interested in its operations are treated
as an entity linked to the flag State. The nationalities of these persons are not relevant.9
As a consequence, as stated in the Third Restatement of the Law, the flag State is entitled to
make claims against other States in case of damage to its ship or injury to the seamen
manning it, regardless of their nationality.
The legal basis of the principle of the exclusive jurisdiction of the flag State was
sometimes explained by the theory of the territoriality of the ship. According to this theory,
a ship is considered as a ‘floating island’ or a ‘detached part of the territory’ of the State to
which it belongs. Nonetheless, the theory of the territoriality of the ship is contrary to the
fact that, in certain circumstances, merchant vessels are subject to the right of visit by
foreign warships, and vessels within internal waters and the territorial seas are in principle
under the territorial sovereignty of the coastal State. Hence the theory of the territoriality
of the ship is obsolete and indefensible for practical reasons. The principle of the exclusive
jurisdiction of the flag State should be considered as a corollary of the freedom of the high
seas and the requirement of the submission of the high seas to law, or, according to Gidel,
the juridicité (or ‘juridicity’) of the high seas. Considering that the high seas are not
subject to any national jurisdiction and there is no centralised authority governing the high
seas, legal order on the high seas can be ensured primarily by the flag State.
The principle of the exclusive jurisdiction of the flag State plays a dual role. First, this
principle prevents any interference by other States with vessels flying its flag on the high
seas. In so doing, the principle of the exclusive jurisdiction of the flag State ensures the
freedom of activity of vessels on the high seas. Second, under this principle, the flag State
has responsibility to ensure compliance with national and international laws concerning
activities of ships flying its flag on the high seas.
The principle of the exclusive jurisdiction of the flag State does not mean that only States
are entitled to fly their flags on their vessels. As provided in Article 7 of the Geneva
Convention on the High Seas and Article 93 of the LOSC, international organisations are
also entitled to fly their own flag on their vessels. Indeed, the International Committee of
the Red Cross (ICRC) has been identifying its vessels by displaying its emblem for decades.
In the UN Emergency Force (UNEF) in Egypt between 1956 and 1957, vessels were chartered by UNEF itself, and the UN flag was flown by certain of these vessels, on some occasions
alone, and on others together with the national flag.
While the obligations of the flag State are diverse, Article 94 of the LOSC specifies in
particular the following duties.
(i) Every State is under the duty to effectively exercise its jurisdiction and control in
administrative, technical and social matters over ships flying its flag. In particular, every
State is obliged to maintain a register of ships containing the names and particulars of ships
flying its flags and to assume jurisdiction under its internal law over each ship flying its
flag and its master, officers and crew in respect of administrative, technical and social
matters respecting the ship.
(ii) Under Article 94(3), every State is obliged to take such measures for ships flying its
flag as are necessary to ensure safety at sea with regard, inter alia, to:
(a) the construction, equipment and seaworthiness of ships;
(b) the manning of ships, labor conditions and the training of crews, taking into account
the applicable international instruments;
(c) the use of signals, the maintenance of communications and the prevention of collisions.
(iii) In taking those measures called for in Article 94(3)(4), each State is required to
conform to generally accepted international regulations, procedures and practices, and to
take any steps which may be necessary to secure their observance (Article 94(5)). ‘Generally
accepted international regulations, procedures and practices’ include treaties adopted
under the auspices of the IMO and the ILO as well as practices on the basis of those
instruments. For example, the seaworthiness of ships is regulated by the 1974 International
Convention for the SOLAS, the 1966 International Convention on Load Lines, the
1971 Agreement on Special Trade Passenger Ships and its Protocol of 1973,22 the 1977 –
International Convention for the Safety of Fishing Vessels and the 1993 Torremolinos
Protocol. Collision at sea is governed by the 1972 Convention on the International
Regulations for Preventing Collisions at Sea. The quality of crews is regulated by the
1976 ILO Convention No. 147 concerning Minimum Standards in Merchant Ships, the
1978 International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, the 1995 International Convention on Standards of Training, Certification
and Watchkeeping for Fishing Vessel Personnel (STCW-F), and the 2006 Maritime Labour
Convention. The role of the ILO is significant in this field.
(iv) Under Article 94(6), a State which has clear grounds to believe that proper jurisdiction
and control with respect to a ship have not been exercised may report the facts to the flag
State. Upon receiving such report, the flag State is obliged to investigate the matter, and if
appropriate, take any action necessary to remedy the situation. Yet this provision does not
provide any further clarity on the concept of ‘clear grounds’ for reporting.
(v) In accordance with Article 94(7), each State is obliged to cause an inquiry into every
marine casualty or incident of navigation on the high seas involving a ship flying its flag
and causing loss of life or serious injury to nationals of another State or serious damage to
ships or installations of another State or to the marine environment. Furthermore, the flag
State and the other State are required to cooperate in the conduct of any inquiry held by
that other State into any such marine casualty or incident of navigation.
One issue which has arisen involves the extent of flag State jurisdiction in the situation
where vessels flying the flags of different States have collided on the high seas. In this
regard, the most often cited instance is the 1927 Lotus case. On 2 August 1926, the French
mail steamer Lotus collided with a Turkish vessel Boz-Kourt on the high seas. As a result of
the collision, the Turkish vessel sank and eight Turkish nationals on board lost their lives.
Upon the arrival of the Lotus in Constantinople, the Turkish authorities instituted criminal
proceedings against, among others, Lieutenant Demons, a French officer of the watch on
board the Lotus at the time of the collision. On 15 September 1926, the Criminal Court
sentenced Lieutenant Demons to eighty days’ imprisonment and a fine of £22. The action of
the Turkish judicial authorities gave rise to a dispute between France and Turkey and, by a
special agreement signed at Geneva on 12 October 1926, the two governments submitted
the case to the PCIJ.
In this case, the PCIJ took the view that ‘there is no rule of international law prohibiting
the State to which the ship on which the effects of the offence have taken place belongs
from regarding the offence as having been committed in its territory and prosecuting,
accordingly, the delinquent’. The Court thus held, by the President’s casting vote, that
Turkey had not acted in conflict with the principle of international law, contrary to Article
15 of the Convention of Lausanne of 24 July 1923. Nonetheless, the Lotus judgment was
much criticised because penal proceedings before foreign courts in the event of collision on

the high seas may constitute an intolerable interference with international navigation. As
a consequence, the 1952 Brussels Convention for the Unification of Certain Rules relating to
Penal Jurisdiction in Matters of Collision and Other Incidents of Navigation provided for the
exclusive jurisdiction of the flag State or of the State of nationality of an offender in the
event of a collision or any other incident of navigation concerning a seagoing ship. This
rule was echoed in Article 11 of the Geneva Convention on the High Seas and Article 97 of
the LOSC. Furthermore, under Article 98(1)(a), every State shall require the master of a ship
flying its flag, in so far as can be done without serious danger to the ship, the crew or the
passengers, to render assistance to any person found at sea in danger of being lost. Article
98(1)(c) of the LOSC places a clear obligation upon every State to require the master of a
ship flying its flag, after a collision, to render assistance to the other ship, its crew and its
passengers. The obligation to render assistance is further amplified by SOLAS and the
1979 Maritime Search and Rescue Convention.

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