A continental shelf is the edge of a continent that lies under the ocean which extends from the coastline of a continent to a drop-off point called as shelf break.[i] A continental shelf holds a great significance for any coastal state because of the fact that it holds many vital natural resources.

As a consequence, there has been a need for the development of law at the international level relating to continental shelf or otherwise different countries of the world might have occupied large portions of the sea-bed and incorporated them into their territory. Accordingly, continental shelves have been included under International law which confirms as well as delimits each coastal state’s right to explore and exploit the natural resources of continental shelf.

The two conventions, namely, the Geneva Convention, 1958 and the U.N. Convention on the Law of the Sea, 1982 (UNCLOS) have played the fundamental role in the shaping of International law with respect to continental shelves. And the U.N. Convention on the Law of the Sea is also the present law on this point, regulating the exploration and exploitation of natural resources of continental shelves.

Meaning and structure of Continental shelf

To define, continental shelf is a broad, relatively shallow submarine terrace of continental crust forming the edge of a continental landmass. Stating simply, continental shelf is the area of seabed around a large land mass where the sea is relatively shallow compared with the open ocean. The continental shelf is geologically part of the continental crust and shelf seas occupy about 7% of the area of the world’s oceans, the majority of the world's continental shelf still being unknown and unmapped.

However, a continental shelf is of national importance not just in the geographical sense, but also in the legal, social and economic sphere because it has abundance of natural resources; it being formed of both organic and inorganic materials accumulated over millions of years.

Regarding the structure, a continental shelf typically extends from the coast to depths of 100–200 metres (330–660 feet). It is gently inclined seaward at an average slope of about 0.1°. In nearly all instances, it ends at its seaward edge with an abrupt drop called the shelf break. Below this lies the continental slope, a much steeper zone that usually merges with a section of the ocean floor called the continental rise at a depth of roughly 4,000 to 5,000 metres (13,000 to 16,500 feet).[ii]

Historical Development of Legal Regime of Continental Shelf

States have always attached great importance to sea due to two important reason, namely:

1. the natural resources of the sea, and
2. from the point of view of national security.

Talking about continental shelf, it too has both the above-mentioned significance. However, though the geographical and geological concept of continental shelf is quite an old one, the legal concept of continental shelf was brought forward by the Gulf of Paria Treaty ,1942 and brought into limelight by the Truman Proclamation of 1945.

The reason for the same being that the concept of continental shelf is essentially related to the exploration of the natural resources from the sea adjacent to the territorial sea. It was thus, not of much importance until the exploration of marine natural resources became technically possible. Until the first quarter of the twentieth century, the submarine areas remained widely unexplored. But due to the progress made in marine technology and the understanding of man of the land under the oceans, the exploration of continental shelves began and gradually enhanced to a great extent during Second World War.

Subsequently, the United Kingdom and United States, although acting independently, initiated a new legal regime of continental shelf for the exploration of mineral and other resources in continental shelves Their initiatives in this regard can be summarised as below:

1. The Gulf of Paria Treaty, 1942

   This treaty was initiated by the United Kingdom with Venezuela. It was the first conscious effort to establish rights or simply control over a large area of sea-bed beyond the territorial waters, that is, continental shelf. In 1936, the Foreign Office of the United Kingdom instructed its embassy in Venezuela to negotiate with the host government in order to arrive at an agreement to delimit the sea-bed and sub-soil of the Gulf of Paria whichis surrounded by the coast of Venezuela and the island of Trinidad. Under it the parties agreed to recognise each other’s rights and control which had been or might hereafter be lawfully acquired, over the specified parts of the submarine area of the Gulf. The treaty referred solely to the submarine areas of the Gulf and clearly mentioned that nothing in the treaty would affect the legal status of the island, islets or rocks above the surface of the sea together with the territorial waters thereof.
   
   Lastly, it is worth noticing that the treaty had not used the term continental shelf nor employed any criteria for delimiting frontiers of the annexed areas. It did not indicate the basis on which the areas had been claimed by the parties. But from the provisions of the treaty, it would be inferred that the limits of territorial waters adjacent to the coast could be acquired by occupation, provided that such occupation did not impinge upon the status of waters above the submerged land.The treaty had thus, used the occupation-theory in support of claiming larger areas of the sea-bed. [iii]
    

2. The Truman Proclamation, 1945

   
   In 1943, the Secretary of the Interior of United States communicated to President Roosevelt for emphasizing the importance of the continental shelf extending some 100 to 150 miles from the shore, to the United States from the point of view of security as well as natural resources. Accordingly, he suggested the laying of a legal regime for full appropriation of the immense natural resources of the continental shelf. Ultimately on September 28, 1945, President Truman signed a Proclamation on the policy of United States with respect to the Natural Resources of the Sub- soil and Sea-bed of the continental shelf.
   
   It laid down that the Government of the United States regards the continental shelf beneath the high seas but contagious to the coasts as a part of the United States and thus, subject to its jurisdiction and control. But in cases where the continental shelf extends to the shores of another state or is shared with an adjoining state, the boundary shall be determined by the United States and the state concerned according to equitable principles. Further it clearly provided that the legal status of high seas and the right to their free navigation are in no way affected by the treaty.
   
   To sum up, like the Gulf of Paria Treaty, this Proclamation too had some inherent defects, the major one being that it did not lay down any criteria for delimiting the frontiers of the submerged areas, between the states concerned and the basis on which such areas could be claimed by the parties. But a subsequent U.S. State Department press release defined continental shelf as submarine land which is contagious to the continent and which is covered by no more than 100 fathoms of water. [iv]
    

3. The Geneva Convention on Continental Shelf, 1958

   
   Encouraged by the said treaty and proclamation certain other states made similar proclamations, for example, Mexico in 1945, Argentina in 1945, Chile in 1947 and Peru, etc. These proclamations necessitated that a definite shape and form should be given to the International Law relating to the continental shelf as it was feared that in the absence of definite International Law on the point different countries of the world might occupy large portions of the sea-bed and incorporate them into their territory. Thus, in order to develop, codify and enforce definite rules of International Law relating to continental shelf and other aspects of the law of sea a conference was called at Geneva in 1958 and as a consequence a convention called as the Convention of Continental Shelf, 1958 was adopted.

Stating briefly, apart from defining and delimiting the boundaries of a continental shelf, the Geneva Convention through its various provisions seeks to establish a balance between the rights of the coastal states over their continental shelf and those of other states making use of the high seas for the purpose of navigation, fishing, etc. with a view to avoid or minimise the conflicts arising out of the competing use of the sea. It does not confer any rights on the other states but it requires the latter to ensure certain facilities to the former in connection with free navigation, fishing, laying of submarine cables on the continental shelf and conducting scientific research into the biological or physical characteristics of the continental shelf.

Article 1 of the convention defines continental shelf as follows:

Continental shelf refers to-

1. to the seabed and subsoil of the submarine areas adjacent to the coast but outside the area of the territorial sea, to a depth of 200metres or, beyond that limit, to where the depth of the superjacent waters admits of the exploitation of the natural resources of the said areas;
2. to the seabed and subsoil of similar submarine areas adjacent to the coasts of islands.

Criticism of the Definition:
The above definition providestwo alternative criteria for defining the area of continental shelf, namely, depth of the sea criteria and exploration criteria. The first criterion is that the continental shelf extends to a depth of 200 metres of the sea because at that time it was thought that exploration of natural resources was not possible beyond this depth from coasts. However, the criterion was not rigid and where the exploitation of resources could be made beyond that limit, that area could also be referred to as continental shelf on the basis of the exploitation criteria.

And the developed statesapplied the exploitation criteria. Thus, if the above definition is accepted a large part of the sea would become part of the continental shelf and the International Relations would be burdened with new set of conflicts. Accordingly, there was a need for a more definite and elaborate law on the point and now the law in this regard is laid down by the U.N. Convention on the Law of Sea, 1982. [v]

The U.N. Convention on the Law of Sea, 1982 (UNCLOS)

UNCLOS has been ratified by 153 nations and is in force since 1994. It specifies under Article 76 national obligations, rights, and jurisdiction over continental shelf up to at least 200 nautical miles or to a maritime boundary. And further, it contains provisions enabling the coastal states to establish their continental shelves beyond 200 nautical miles also, but, according to and subject to the conditions given therein. To date, seven submissions for extended continental shelves (ECS) have been filed under UNCLOS (Annex II).

Before, looking into the specific provisions of the convention relating to continental shelf it isworth mentioning that they have been influenced by and are largely based on the decision of the International Court of Justice in the North Sea Continental Shelf Case (1969). In this case the Court had observed that:
the rights of the coastal state in respect of the area of continental shelf that constitutes natural prolongation of its land territory into and under the sea, exist ispo facto and ab initio by virtue of its sovereignty over the land and as an extension of it in exercise of sovereign rights for the purpose of exploring the sea-bed and exploiting its natural resources. Here, there is an inherent right of the coastal state.

The Court further held,  what confers the ispo jure title with International Law, which attributes to the coastal states in respect of continental shelf, is the fact that submarine areas may be deemed to be actually part of the territory over which the coastal state has already dominion in that sense that although covered with water, they are a prolongation or continuation of that territory, an extension of it under the sea. [vi]

1. Definition of Continental Shelf

   Article 76 of the convention thus, defines continental shelf as follows:
   The continental shelf of a coastal State comprises the seabed and subsoil of the submarine areas that extend beyond its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines from which the breadth of the territorial sea is measured where the outer edge of the continental margin does not extend up to that distance.
   
   Thus, the above definition incorporates in the first part, the concept of continental shelf as highlighted by the International Court of Justice in the North Sea Continental Shelf Case, and in the second part provides for a uniform continental shelf up to a distance of 200 nautical miles to those coastal states which have a short continental shelf and their continental shelf does not extend to the said distance. Therefore, the convention has set at rest the controversy as to the definition of continental shelf.
    
2. Outer Limits of Continental Shelf
   Paragraph 4(a) of Article 76 of U.N Convention on the Law of the Sea, 1982 provides:
   "For the purposes of this convention, the coastal State shall establish the outer edge of the continental margin wherever the margin extends beyond 200 nautical miles from the baselines from which the breadth of the territorial sea is measured, by either:
   (i) A line delineated in accordance with paragraph 7 by references to the outermost fixed points at each of which the thickness of sedimentary rocks is at least 1 per cent of the shortest distance from such point to the foot of the continental slope; or
   (ii) A line delineated in accordance with paragraph 7 to fixed points not more than 60 nautical miles from the foot of the continental slope."
   
   So, Paragraph 4(a) lays down the method of establishing the outer edge of the established continental margin or in simpler terms, the seaward boundary of the continental shelf beyond 200 nautical miles. Further, the convention also lays down the formula for fixing the precise limits of the Continental Shelf of a coastal state in Paragraph 5 of Article 76 in the following words:
   
   "The fixed points comprising the line of the outer limits of the Continental Shelf on the sea bed, drawn in accordance with paragraph 4(a) (i) and (ii), either shall not exceed 350 nautical miles from the baselines from which the breadth of the territorial sea is measured or shall not exceed 100 nautical miles from the 2,500 metres is obath, which is a line connecting the depth of 2,500 metres."
   
   Illustration
   A State C’s Exploration Ship discovers oil below the depth of 1500 metre in the Seabed at a distance of 190 miles from the Indian coast. India claims that she has exclusive rights to exploit and use this oil. The question which arises is whether India’s claim is justified or not. India's claim is justified because as for definition of continental shelf in Article 76 of the Convention the continental shelf of a coastal State extends to the edge continental margin or 200 nautical miles where the outer edge of the continental margin does not extend upto that distance.
   
   Moreover, outer limit of the continental shelf may be upto 350 nautical miles from the baselines or may not exceed 100 nautical miles from the 2,500 metres isobath. Since 'C' State has discovered oil below the depth of 1500 metres in the Seabed at a distance of 190 miles from the Indian coast, it is clearly within the continental shelf of India. [vii]
    
3. Commission on the Limits of the Continental Shelf
   The Convention also establishes a Commission on the Limits of the Continental Shelf. Paragraph 8 of the Article 76 of the Convention provides that information on the limits of the Continental Shelf beyond the 200 nautical miles from the baselines (which is dealt by paragraph 4(a), paragraph 5 and paragraph 7) shall be submitted by the coastal state to the Commission on the Continental Shelf set up under Annex II and the work of the Commission is to make recommendations to the coastal state on matters related to the establishment of the outer limits of their Continental Shelf. Lastly,the limits of the shelf established by a coastal state on the basis of these recommendations shall be final and binding.

The detailed provisions relating to the Commission are contained in Annex II of the Convention. Article 1 of Annex II provides thata commission on the limits of the Continental Shelf beyond 200 nautical miles in accordance with Article 76 shall be established. Article 4 of Annex II provides that the concerned coastal stateshall submit particulars of extended boundary to the Commission along with supporting scientific and technical data as soon as possible but within 10 years of the entry into force of this convention for that State.

Further according to Article 6 of Annex II the Commission shall consider data and other material submitted by coastal states and then make recommendations in writing to the coastal state which made the submission and to the Secretary-General also.

Lastly, Article 8 of Annex II provides that in case of disagreement of the coastal state with recommendations made by the Commission, the coastal state shall, within reasonable time make a revised or a new submission to the Commission.

North Sea Continental Shelf Case (1969)

Article 6(2) of the Geneva Convention, 1958 provides:

where the same Continental Shelf is adjacent to the territories of two adjacent states, the boundary of the Continental Shelf shall be determined by agreement between them. In the absence of agreement, and unless another boundary line is justified by special circumstances, the boundary shall be determined by application of the principle of equidistance from the nearest points of the baselines from which the breadth of the territorial sea of each state is measured.

And in the North Sea Continental Shelf Case (1969)the International Court of Justice considered this principle of equidistance in such a remarkable manner thatthe Court’s judgement will long be remembered for its classical exposition of the principle governing delimitation of continental shelf between two or more states.

1. Detailed Analysis of the Case
   Germany’s North Sea Coast is concave, whereas, Netherlands’ and Denmark’s Coasts are convex. When a dispute arose between these states regarding the delimitation of their continental shelf both Denmark and Netherlands relied on a multilateral treaty among them and Germany which provided for delimitation by the equidistance method.
   
   The treaty permitted the signatory states to reserve their position with respect to the equidistance method. Germany had signed the treaty but had not ratified it and moreover, it had reserved its position with respect to delimitation by the equidistance method, which might have adversely affected its own continental shelf.
   
   Further, it was contented by Denmark and Netherlands that the configuration of the German North Sea coast did not amount to ‘special circumstances ‘as mentioned in Article 6(2) of the Geneva Convention, 1958 and thus, the delimitation must be according to the equidistance method. They even maintained that the method has emerged into a custom also and thus was binding on Germany.
   
   Germany rejected the obligatory character of the method, as a custom, on the ground of absence of opinion juris on its part. Further, it contended that the different configuration of its coast amounts to special circumstances under the above-mentioned article. Thus, the correct rule for delimitation of the continental shelf is one according to which each state gets a just and equitable share of the continental shelf, in proportion to the length of its coast line or sea frontage.
    
2. Judgement of the Case
   By majority of eleven votes to six, the World Court finally held that the use of the equidistance method of delimitation was not obligatory between the parties of the case; and thus, there being no single method of delimitationthe use of which is in all circumstances obligatorythe principles applicable to the parties in this case are as follows:
   
   (1) Delimitation is to be affected by agreement in accordance with equitable principles, and taking into account of all the relevantcircumstances, in such a way to leave as such possible to each party allthose parts of the Continental Shelf that constitute a naturalprolongation of its land territory into and under the sea, withoutencroachment on the natural prolongation of the land territory of the other;
   
   (2) if in the application of the preceding sub-paragraph, the delimitation leaves to the parties areas that overlap, these are to be divided between them in agreed proportions, or failing agreement, equally, unless they decide on a regime of joint jurisdiction, user or exploitation for the zones of overlap or any part of them;
   
   (3) in the course of negotiations, the factors to be taken into account are to include:
   (a) the general configuration of the coasts of the parties as well as the presence of any special or unusual features;
   (b) so far as known or readily ascertainable the physical and geological structure and natural resources, of the Continental Shelf areas involved;
   (c) the element of a reasonable degree of proportionality, which a delimitation carried out in accordance with equitable principles ought to bring about. [viii]

Being influenced by the above decision of the International Court of Justice, Article 83 of the U.N. Convention on the Law of the Sea, 1982, provides that delimitation of Continental Shelf between states with opposite or adjoining coasts shall be made by agreement on the basis of international law, as referred to in Article 38 of the Statute of the International Court of Justice, in order to achieve an equitable solution.

In case no agreement can be reached within a reasonable period of time, the states concerned shall resort to the procedure provided under Part XV dealing with the Settlement of Disputes. And during the pendency of the settlement, the states concerned in spirit of understanding and co-operation, shall make every effort to enter into provisional arrangements of a practical nature, and, during this transactional period, not to jeopardise prejudice to the final delimitation.

Where there is an agreement in force between the states concerned, questions relating to the delimitation of Continental Shelf shall be determined in accordance with the provision of that agreement.

Thus the 1989 Convention does not at all mention the principle of equidistance. It emphasizes agreement between the parties. However, parties "in order to achieve an equitable solution" may take into account the principle of equidistance.

Significance of the U.N. Convention on the Law of Sea, 1982 (UNCLOS) in the present time

The Convention is playing a very significant role in international relations with the increasing significance of continental shelves, in the sense that the coastal states are now more and more willing to explore the shelf areas for exploiting their natural resources.

The Convention lays down various rights of the coastal states in respect of continental shelf areas, the most important provision of the Convention being the one relating to delimitation of continental shelf.

The area of continental shelf cannot be appropriated by the coastal states, and therefore, they cannot exercise sovereignty over it. However, the states may exercise sovereign rights over it for the purposes of exploring it and exploiting its natural resources upto 200 nautical miles.

Also, according to Article 76 of the Convention the coastal states may determine the outer limits of the continental shelf as well, in accordance with and subject to the limitations given therein.

In this regard Article 82 further provides that those coastal states which exploit the non-living resources of the continental shelf beyond 200 nautical miles are required to make payments or contributions in kind to the International Sea-bed Authority. And the rate of payments and contributions shall be according to Article 83, and be made annually.

Another important provision is laid down under Article 77 which provides that the above rights of exploring and exploiting are exclusive. It means that if the coastal state does not explore the continental shelf or exploit its natural resources, no other state cancarry out these activities without its express consent.

Article 81 also provides that the coastal states shall have the exclusive right to authorise and regulate drilling on the continental shelf for any purposes. And according to Article 85 they have a right to exploit the subsoil by way of tunnelling, irrespective of the depth of water above the subsoil.

Apart from the rights of the coastal states, the Convention makes some provisions for the rights of the other states as well.

1. Firstly, Article 78 maintains that the above rights of the coastal states over the continental shelf do not affect the legal status of the superjacernt waters or of the air space above them.
2. Secondly, the exercise of the right of the coastal states over the continental shelf must not infringe or result in any unjustifiable interference with navigation rights and freedom of other States.

Thus, coastal States are entitled only to construct and operate the necessary installations within their continental shelf in accordance with these safeguards. Further, the other states are entitled to lay submarine cables and pipelines on the continental shelf. But the right can be exercised only with the consent of the coastal states. The coastal State for giving consent of giving may impose conditions for cables or pipelines.

Indian Position on Continental Shelf

Indian position on continental shelf has been made clear under Section 6 of the Maritime Zones Act of 1976. Part 1 of the above Section lays down that the continental shelf of India comprises:
"the sea-bed and subsoil of the sub-marine areas that extend beyond the limit of the territorial waters throughout the natural prolongation of its land territory to the outer edge of the continental margin or to a distance of 200 nautical miles from the baseline….where the outer edge of the continental margin does not extend up to that distance."

The Act also laid down under Section 6, Para 3:
The Union has:

1. sovereign rights for the purposes of exploration, exploitation, conservation and management of all resources;
2. exclusive rights and jurisdiction for the construction, maintenance or operation of artificial Islands, off-shore terminals, installations and other structures and devices necessary for the continental shelf or for convenience of shipping or any other purpose;
3. exclusive jurisdiction to authorise, regulate and control scientific research, and
4. exclusive jurisdiction to preserve and protect the marine environment and to prevent and control marine pollution.

It is further provided that no person (including a Foreign Government) shall, except under, and in accordance with, the terms of licence or a letter of authority granted by the Central Government, explore the continental shelf or carry on any search or drill therein or construct or conduct any research with the continental shelf or drill therein or construct, maintain or operate any artificial Islands, off shore terminals, installations or other structure or device therein for any purpose.

Thus, the Indian position is consistent with the provisions of the U.N. Convention on the Law of the Sea, 1982.

Conclusion
The geographical concept of continental shelf is an old one but the legal regime regarding continental shelves at the International level is of quite a recent origin. It started from the Gulf of Paria Treaty ,1942, followed by the Truman Proclamation of 1945. Then the Geneva Convention of 1958 was a major convention on this point but it had some inherent defects, particularly in the definition of continental shelf, provided under the Convention.

At present, the law relating to continental shelf is provided by the U.N. Convention on the Law of Sea, 1982. Also, the remarkable judgement of the International Court of Justice in the North Sea Continental Shelf Case (1969) laid down some very important rules rather guidelines for the delimitation of continental shelf.

Further, it is worth mentioning that the U.N. Convention on the Law of Sea, 1982 is a very comprehensive one, dealing with all the aspects of continental shelf delimitation, the various rights of the coastal states as well of the other states.

Thus, it not only seeks to avoid conflicts among the coastal states but also to strikes a balance between the rights of the coastal and other states. To sum up, it can be stated that the adoption of the continental shelf concept has been so rapid, due to the natural resources of continental shelf as well as from the point of view of security of the coastal states also, that the U.N. Convention on the Law of Sea has acquired an important place in the sphere of International Law.

End-Notes:

1. Continental Shelf, available at:https://www.nationalgeographic.org/encyclopedia/continental-shelf/ (last visited on October 13, 2019).
2. Continental Shelf, available at: https://www.britannica.com/science/continental-shelf (last visited on October 13, 2019).
3. S.P. Gupta, International Law and Human Rights 158 (Allahabad Law Agency, Faridabad, 1st edn., 2009).
4. S.K. Kapoor, International Law & Human Rights 265 (Central Law Agency, Allahabad, 19th edn., 2014).
5. Dr. H.O. Agarwal, International Law & Human Rights 140 (Central Law Publications, Allahabad, 20th edn., 2014).
6. I.C.J. Reports (1969), p.3.
7. S.K. Kapoor, International Law & Human Rights 268 (Central Law Agency, Allahabad, 19th edn., 2014).
8. I.C.J. Reports (1969), p.3.