Understanding the Language of the Law of the Sea

With the disputes concerning the West Philippine Sea in the South China Sea and recently, the issues surrounding Benham Rise, we see how the United Nations Convention on the Law of the Sea or the Law of the Sea Convention (LOSC)1 affects the maritime entitlements of the Philippines. It is indeed imperative for the Philippine state, a maritime nation, to understand the law of the sea and the LOSC, which is its primary reference material in dealing with its public maritime concerns. A comprehensive understanding of the LOSC avoids a piece-meal approach to issues and provides a holistic view that is in mindful of the history, spirit and aims of its provisions. Further, being a member of the international community, the Philippine state has to be cognizant of the interplay between its domestic laws and its international obligations stemming from an international convention, such as the LOSC.

Law of the Sea and the LOSC as a source of international obligation

‘Law of the sea’ refers to that branch of international maritime law, which deals with its public aspect. Included herein are issues on maritime zones, exercise of sovereignty, sovereign rights, jurisdiction, marine environmental protection and conservation of ocean resources. ‘Law of the sea’ is not concerned with matters relating to carriage of goods, maritime insurance, salvage and towage, et cetera, which are within the private realm of maritime law. Whilst private maritime laws vary across different jurisdictions, the law of the sea is primarily governed by the LOSC, which is regarded as the ‘Constitution for the Oceans’.

The LOSC is the product of the third United Nations Conference on the Law of the Sea (UNCLOS III), which was convened from 1973 until 1982 when the text of the convention was finally adopted. Later that year the treaty was opened for signature. Having signed and ratified the same, the Philippines, therefore, is a party to the LOSC.

Article 38 of the Statute of the International Court of Justice is widely recognized as laying down the different sources of international law; one of these sources is ‘international conventions’. As a member of the international community, a state-party to an international convention or a treaty has the obligation to uphold its international commitments arising therefrom that which may necessitate having to reconcile the same with its domestic laws.2

Indeed, the important question as to which prevails between a state’s domestic laws and a valid and binding treaty may appear to be academic when a state is pleading before an international court/tribunal. A state cannot be expected to ask for the benefits of a treaty, yet refuses to recognize or comply with the obligations arising therefrom. A state’s insistence upon the supremacy of its domestic laws may actually prevent it from invoking the provisions of an international treaty. This approach may then leave the practical effect that the state is unable to fully avail of the treaty’s benefits and protection.

Development of the law of the sea

The idea that a state or king could have ‘command of the sea’ had been generally accepted as early as the times of the Greek and Roman empires. During the Middle Ages, Venice likewise made claims of sovereignty over the whole of the Adriatic whilst certain states made claims for control over large parts of the Baltic.

A crucial development in the history of the law of the sea happened in 1493 when Pope Alexander VI of the Roman Catholic Church issued a Papal Bull that divided the world between Spain and Portugal. In the 1494 Treaty of Tordesillas the division was renegotiated; having the Cape Verde Islands as the starting point, it granted the territories west of the drawn line to Spain and those east thereof to Portugal. Further, in 1529, the East Indies was likewise divided between Spain and Portugal under the Treaty of Zaragoza. In 1609, James I of England claimed sovereignty over the areas around Great Britain, which areas he designated as the ‘English Seas.’

Being excluded from commerce in the English Seas and the lucrative spice trade in the East Indies, the Dutch East India Company engaged Hugo Grotius to argue on its behalf the concept of ‘freedom of the seas’; thus, the seas could not be appropriated. In his work ‘Mare Liberum’ he presented this idea based upon the vastness of the oceans and inexhaustibility of its resources.

Several writers opposed Grotius’s idea of free seas. One of them was the Englishman John Selden who published in 1635 his work ‘Mare Clausum’ supporting the idea of ‘closed seas’. Thus began what would be called in the history of the law of the sea as the ‘battle of the books’, a battle said to have been won by the advocates of free seas which advanced the political and economic interests of the world powers of the time. Free seas meant free navigation, free use of resources and free trade.

The birth of the concept of the modern state following the fall of the Roman Empire brought with it the development of the idea of a territorial sea – a maritime zone to which the national jurisdiction of a coastal state extended. By the 19th century, the concept of a territorial sea was generally established under international law. It was recognized that a belt of water surrounding a state pertained to such state; beyond that were the high seas that were free for use by all states. Apart from the maritime easement of ‘innocent passage’ in favor of other states, a coastal state’s hold over the territorial sea was plenary. In the high seas, on the other hand, freedom of other states, particularly in respect of navigation and fishing, was recognized and observed. Thus, the oceans were divided into two zones – the territorial sea and the high seas – governed by the principle of sovereignty and principle of freedom, respectively. This dualism, which would form part of customary international law,3 demonstrated the balance between the opposing concepts of mare liberum and mare clausum.

Until the 20th century, rules concerning the law of the sea were in the form of customary international law; there was no codified body of rules governing the use of the seas. The 1930 Hague Conference for the Codification of International Law instigated by the League of Nations4 is the first inter-governmental effort to codify the law of the sea. (There were attempts from various non-governmental bodies earlier.) In particular, the 1930 Hague Conference dealt with the issues of the nature of the rights possessed by a coastal state over its territorial sea and its breadth. Whilst the first issue was settled in favor of territorial sovereignty, which extended not only to the waters but also to the seabed and subsoil underneath and the airspace above, the issue on the breadth of the territorial sea was unresolved. Different states had varying claims on the extent of the territorial sea – the United States adopted the three-mile limit, some Scandinavian countries claimed four miles, some would claim 200 miles, et cetera. Thus, the conference failed to adopt a convention on the territorial sea.

The lack of uniformity in the practice of different states as regards the breadth of the territorial sea affected the development of the concept of a contiguous zone, a zone contiguous to and seaward of the territorial sea. In said zone, the coastal state was given limited powers and enforcement jurisdiction.

A new development in the law of the sea came after World War II during which time there had been an increasing demand for offshore natural resources. In 1945, US President Harry Truman made the first clear assertion that the resources of the continental shelf, deemed the natural prolongation of the coastal state’s land mass, were subject to the coastal state’s jurisdiction and control. Aware that a claim of sovereignty beyond the territorial sea would diminish the area of high seas where it extensively exercised its freedom of navigation as a maritime power, the US devised the idea that its claim was only on the continental shelf; it would not affect the legal status of the superjacent waters which remained part of the high seas. From this development we see the genesis of the concept of sovereign rights in the law of the sea in contrast with the plenary concept of sovereignty. Moreover, it demonstrates the beginning of the split in the legal nature of the water column and the seabed and subsoil beyond the area of the territorial sea.

By 1947, the United Nations through the International Law Commission (ILC) started its work on the codification of the law of the sea. The report of the ILC became the basis for the work of the first United Nations Conference on the Law of the Sea (UNCLOS I), which was convened in Geneva in 1958. UNCLOS I successfully adopted four conventions – on the territorial sea and contiguous zone, the high seas, fishing and conservation of living resources of the high seas, and on the continental shelf – and provided the first codification of the law of the sea.

After UNCLOS I, most concepts on the territorial sea were codified; the concept of a contiguous zone was established; the continental shelf regime was developed – the seaward limit was defined by the depth and exploitability criteria, and the idea of ‘sovereign rights’ to describe a coastal state’s rights over the continental shelf was formed.

Unfortunately, the issue on the breadth of the territorial sea was not resolved at UNCLOS I. Thus, the geographical scope where coastal state sovereignty extended was not defined. A second conference in 1960 (UNCLOS II) was convened; however, it still failed to successfully address this particular issue along with the related issue of fishery zone.

The year of 1967 was an important point in the further development of the law of the sea. Then, Ambassador to the UN Arvid Pardo of Malta proposed the examination of the deep seabed beyond the limits of national jurisdiction in view of the concern that only developed states, which had the technology and means, could benefit from the extraction of the resources therefrom. Thus, the UN General Assembly formed the Sea Bed Committee. Around that time as well there was the increasing concern for marine environmental protection especially after the Torrey Canyon incident in 1967. Likewise, the international political scene was changing with the emergence of newly independent developing states, which had no role in the drafting of the 1958 Geneva conventions.

Further, in the 1970s certain Asian, African and Latin American states echoed earlier proposals and put forward the idea of an exclusive economic zone (EEZ). This move was a reflection of the desire of developing states for control over the resources, particularly fish stocks, off their coasts.

In view of the above circumstances and the inter-relatedness of copious issues on the law of the sea, UNCLOS III was convened in 1973 to produce a comprehensive law of the sea convention.

The LOSC and the maritime zones

Source: Google Images

Upon the adoption of the LOSC in 1982, the concept of a territorial sea was enhanced in that its breadth was finally determined to be no more than 12nm from the coastal state’s baselines. Following the traditional understanding of a territorial sea, the coastal state’s powers in said zone are plenary. Coastal state sovereignty extends to the said area without prejudice to the right of innocent passage exercisable by other states. Related concepts, such as transit passage and archipelagic sea lanes passage, likewise modified the territorial sea regime, which concepts reflect the compromises reached by affected states in relation to straits used for international navigation and archipelagic waters.

Where a state claims a contiguous zone, it is contiguous to said state’s territorial sea and may extend up to 24nm from the baselines. It is a zone intended for fiscal, immigration, sanitary and customs concerns as well as regulations on archaeological and historical objects found at sea.

Consistent with its original wisdom, the continental shelf regime in the LOSC deals with the resources of the seabed and does not affect the water column or the resources therein, particularly fish stocks. Over the continental shelf, the coastal state exercises not sovereignty but sovereign rights for the purpose of exploring it and exploiting its natural resources, i.e. mineral and other non-living resources together with living organisms belonging to sedentary species. It is important to note that, as held in the North Sea Continental Shelf cases (1969), ‘the rights of the coastal state in respect of the area of continental shelf […] exist ipso facto and ab initio […].’

Departing from the depth and exploitability criteria for the limit of the continental shelf, UNCLOS III fixed the breadth of a coastal state’s continental shelf at 200nm, irrespective of the topography of the underwater terrain. The notion of an outer continental shelf, whose limits are subject to the approval by the Commission on the Limits of the Continental Shelf (CLCS) and in regard to which certain obligations are to be performed in favor of the International Seabed Authority (ISA),5 was likewise developed to reconcile the objections of certain states claiming more than 200nm. Certainly, the outer continental shelf is limited to 350nm to address Ambassador Pardo’s idea that the resources of the deep seabed pertain to no state but to all of mankind. Thus, beyond this 200nm (or 350nm) zone is The Area, a space treated as res communis following a new principle in the law of the sea: common heritage of mankind.

The fixing of the territorial sea’s breadth could not have been facilitated without the introduction of the exclusive economic zone (EEZ) regime to the LOSC. Where a state claims an EEZ – a zone beyond the territorial sea up to 200nm from the baselines6 –, it shall have, inter alia, sovereign rights for the purpose of exploring and exploiting, conserving and managing the natural resources, whether living or non-living, of the waters in said zone. Thus, as a compromise on certain states’ earlier claims of a 200nm territorial sea, the EEZ regime providing for sovereign rights has enabled coastal states to nationalize the economic resources beyond the territorial sea without extending the geographical scope of a coastal state’s sovereignty.

Whilst rights over the continental shelf need not be constituted for they exist ipso facto and ab initio, the EEZ needs to be claimed by a coastal state. As recognized in the Libya/Malta Continental Shelf cases (1985), there can be a continental shelf without an EEZ, but there cannot be an EEZ without a continental shelf. Consequently, the waters superjacent to the continental shelf may either be EEZ or high seas. Thus, states’ rights over said waters depend on whether they form part of a state’s EEZ or the high seas. To be sure, the waters superjacent to the outer continental shelf, i.e. beyond 200nm, are always the high seas where the principle of freedom – of navigation, overflight, communications, fishing, etc – applies.


A state’s maritime entitlements per the LOSC can be best understood if one is mindful of the evolution of the law of the sea and the development of the different maritime zones. Transforming the traditional dichotomy between the principle of sovereignty and principle of freedom, the LOSC embodies new concepts that are reflective of the compromises reached to cater to the needs of other states, particularly developing states whose voices were heard and listened to at UNCLOS III.

In discussing law of the sea concerns, it is important to realize the distinct and separate nature and functions of each maritime zone and to identify which rights are possessed by states in relation thereto. As has been presented, sovereignty is different from sovereign rights; innocent passage, transit passage, archipelagic sea lanes passage, the exercise of the freedom of navigation are certainly distinct concepts; whilst they are both governed by the same 200nm limit, the continental shelf regime and the EEZ regime are separable. These, inter alia, are neither synonymous nor inter-changeable.

The law of the sea is a specialized field of international law. Inevitably, when a state talks about law of the sea issues, the international community is the unavoidable audience. The law of the sea has its own language, and understanding it can bring about a more constructive discussion of issues, and places one in a better position to address law of the sea concerns.

Atty. Julius A. Yano is a member of the Institute for Maritime and Ocean Affairs. He obtained his Juris Doctor degree from the University of the Philippines, College of Law and his Master of Laws degree in International Maritime Law from the IMO International Maritime Law Institute in Malta. Subsequently, he attended the Summer Academy at the International Tribunal for the Law of the Sea (ITLOS) in Hamburg, Germany.

  1. Following eminent commentators on the subject, the writer uses the abbreviation ‘LOSC’ to refer to the 1982 United Nations Convention on the Law of the Sea as ‘UNCLOS’ is used to refer to the different United Nations Conferences on the Law of the Sea as discussed below.
  2. The Vienna Convention on the Law of Treaties, to which the Philippines is a party, provides in its Article 27 that ‘[a] party may not invoke the provisions of its internal law as justification for its failure to perform a treaty. […]’
  3. Customary international law as a source of international law deserves a more thorough discussion in the proper forum. Suffice it to say that obligations from a treaty may be binding even upon non-parties thereto if said obligations form part of customary international law, subject to the idea of a ‘persistent objector’, which is however further subject to the concept of jus cogens. Thus, in the context of the law of the sea, certain provisions in the LOSC may be opposable even to non-parties not as conventional obligations but as rules of customary international law.
  4. Predecessor of the United Nations (UN).
  5. Together with the ITLOS, the permanent tribunal for law of the sea disputes, these institutions are creations of the LOSC.
  6. Thus, where a state claims a contiguous zone and an EEZ, the contiguous zone is consequently within its EEZ. Where there is a contiguous zone but no EEZ, the contiguous zone is part of the high seas.