The closed seas concept proclaimed by Spain and Portugal in the fifteenth and sixteenth centuries, and supported by the Papal Bulls of 1493 and 1506 dividing the seas of the world between the two powers, was replaced by the notion of the open seas and the concomitant freedom of the high seas during the eighteenth century. The essence of the freedom of the high seas is that no state may acquire sovereignty over parts of them. This is the general rule, but it is subject to the operation of the doctrines of recognition, acquiescence and prescription, where, by long usage accepted by other nations, certain areas of the high seas bounding on the territorial waters of coastal states may be rendered subject to that state’s sovereignty. This was emphasised in the Anglo-Norwegian Fisheries case. The high seas were defined in Article 1 of the Geneva Convention on the High Seas, 1958 as all parts of the sea that were not included in the territorial sea or in the internal waters of a state. This reflected customary international law, although as a result of developments the definition in article 86 of the 1982 Convention includes: all parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a state, or in the archipelagic waters of an archipelagic state. Article 87 of the 1982 Convention (developing article 2 of the 1958 Geneva Convention on the High Seas) provides that the high seas are open to all states and that the freedom of the high seas is exercised under the conditions laid downin the Convention and by other rules of international law. It includes inter alia the freedoms of navigation, overflight, the laying of submarine cables and pipelines, the construction of artificial islands and other installations permitted under international law, fishing, and the conduct of scientific research. Such freedoms are to be exercised with due regard for the interests of other states in their exercise of the freedom of the high seas, and also with due regard for the rights under the Convention regarding activities in the International Seabed Area. Australia and New Zealand alleged before the ICJ, in the Nuclear Tests case, that French nuclear testing in the Pacific infringed the principle of the freedom of the seas, but this point was not decided by the Court. The 1963 Nuclear Test Ban Treaty prohibited the testing of nuclear weapons on the high seas as well as on land, but France was not a party to the treaty, and it appears not to constitute a customary rule binding all states, irrespective of the treaty.
Nevertheless, article 88 of the 1982 Convention provides that the high seas shall be reserved for peaceful purposes. Principles that are generally acknowledged to come within article 2 include the freedom to conduct naval exercises on the high seas and the freedom to carry out research studies. The freedom of navigation is a traditional and well-recognised facet of the doctrine of the high seas, as is the freedom of fishing. This was reinforced by the declaration by the Court in the Fisheries Jurisdiction cases300 that Iceland’s unilateral extension of its fishing zones from 12 to 50 miles constituted a violation of article 2 of the High Seas Convention, which is, as the preamble states, ‘generally declaratory of established principles of international law’. The freedom of the high seas applies not only to coastal states but also to states that are landlocked. The question of freedom of navigation on the high seas in times of armed conflict was raised during the Iran–Iraq war, which during its latter stages involved attacks upon civilian shipping by both belligerents. Rather than rely on the classical and somewhat out-of-date rules of the laws of war at sea, the UK in particular analysed the issue in terms of the UN Charter. The following statement was made: The UK upholds the principle of freedom of navigation on the high seas and condemns all violations of the law of armed conflicts including attacks on merchant shipping. Under article 51 of the UN Charter, a state actively engaged in armed conflict (as in the case of Iran and Iraq) is entitled in exercise of its inherent right of self-defence to stop and search a foreign merchant ship on the high seas if there is reasonable ground for suspecting that the ship is taking arms to the other side for use in the conflict. This is an exceptional right: if the suspicion proves to be unfounded and if the ship has not committed acts calculated to give rise to suspicion, then the ship’s owners have a good claim for compensation for loss caused by the delay. This right would not, however, extend to the imposition of a maritime blockade or other forms of economic warfare.

Jurisdiction on the high seas

The foundation of the maintenance of order on the high seas has rested upon the concept of the nationality of the ship, and the consequent jurisdiction of the flag state over the ship. It is, basically, the flag state that will enforce the rules and regulations not only of its own municipal law but of international law as well. A ship without a flag will be deprived of many of the benefits and rights available under the legal regime of the high seas. Each state is required to elaborate the conditions necessary for the grant of its nationality to ships, for the registration of ships in its territory and for the right to fly its flag. The nationality of the ship will depend upon the flag it flies, but article 91 of the 1982 Convention also stipulates that there must be a ‘genuine link’ between the state and the ship. This provision, which reflects ‘a well established rule of general international law’, was intended to check the use of flags of convenience operated by states such as Liberia and Panama which would grant their nationality to ships requesting such because of low taxation and the lack of application of most wage and social security agreements. This enabled the ships to operate at very low costs indeed. However, what precisely the ‘genuine link’ consists of and how one may regulate any abuse of the provisions of article 5 are unresolved questions.

Some countries, for example the United States, maintain that the requirement of a ‘genuine link’ really only amounts to a duty to exercise jurisdiction over the ship in an efficacious manner, and is not a pre-condition for the grant, or the acceptance by other states of the grant, of nationality. An opportunity did arise in 1960 to discuss the meaning of the provision in the IMCO case. The International Court was called upon to define the ‘largest ship-owning nations’ for the purposes of the constitution of a committee of the Inter-Governmental Maritime Consultative Organisation. It was held that the term referred only to registered tonnage so as to enable Liberia and Panama to be elected to the committee. Unfortunately, the opportunity was not taken of considering the problems of flags of convenience or the meaning of the ‘genuine link’ in the light of the true ownership of the ships involved, and so the doubts and ambiguities remain.

The UN Conference on Conditions of Registration of Ships, held under the auspices of the UN Conference on Trade and Development, convened in July 1984 and an agreement was signed in 1986. It attempts to deal with the flags of convenience issue, bearing in mind that nearly one-third of the world’s merchant fleet by early 1985 flew such flags. It specifies that flag states should provide in their laws and regulations for the ownership of ships flying their flags and that those should include appropriate provision for participation by nationals as owners of such ships, and that such provisions should be sufficient to permit the flag state to exercise effectively its jurisdiction and control over ships flying its flag. The issue of the genuine link arose in the context of the Iran–Iraq war and in particular Iranian attacks upon Kuwaiti shipping. This prompted Kuwait to ask the UK and the USA to reflag Kuwaiti tankers. The USA agreed in early 1987 to reflag eleven such tankers under the US flag and to protect them as it did other US-flagged ships in the Gulf. The UK also agreed to reflag some Kuwaiti tankers, arguing that only satisfaction of Department of Trade and Industry requirements was necessary. Both states argued that the genuine link requirement was satisfied and, in view of the ambiguity of state practice as to the definition of genuine link in such instances, it is hard to argue that the US and UK acted unlawfully.

The International Tribunal for the Law of the Sea in M/V Saiga (No. 2) has underlined that determination of the criteria and establishment of the procedures for granting and withdrawing nationality to ships are matters within the exclusive jurisdiction of the flag state, although disputes concerning such matters may be subject to the dispute settlement procedures of the 1982 Convention. The question of the nationality of a ship was a question of fact to be determined on the basis of evidence adduced by the parties. The conduct of the flag state, ‘at all times material to the dispute’, was an important consideration in determining the nationality or registration of a ship. The Tribunal has also confirmed that the requirement of a genuine link was in order to secure effective implementation of the duties of the flag state and not to establish criteria by reference to which the validity of the registration of ships in a flag state may be challenged by other states. Ships are required to sail under the flag of one state only and are subject to its exclusive jurisdiction (save in exceptional cases).Where a ship does sail under the flags of more than one state, according to convenience, it may be treated as a ship without nationality and will not be able to claim any of the nationalities concerned. A ship that is stateless, and does not fly a flag, may be boarded and seized on the high seas. This point was accepted by the Privy Council in the case of Naim Molvan v. Attorney-General for Palestine, which concerned the seizure by the British navy of a stateless ship attempting to convey immigrants into Palestine.

The basic principle relating to jurisdiction on the high seas is that the flag state alone may exercise such rights over the ship.318 This was elaborated in the Lotus case, where it was held that ‘vessels on the high seas are subject to no authority except that of the state whose flag they fly’.320 This exclusivity is without exception regarding warships and ships owned or operated by a state where they are used only on governmental non-commercial service. Such ships have, according to articles 95 and 96 of the 1982 Convention, ‘complete immunity from the jurisdiction of any state other than the flag state’.