North Sea Continental Shelf Cases

North Sea Continental Shelf Cases (Summary)

International Court of Justice Contentious Case: The North Sea Continental Shelf Cases (Germany/Denmark; Germany/Netherlands).

Year of Decision: 1969.

Note: This post discusses only  aspects of the case related to treaty and customary international law.

Overview: The jurisprudence of the North Sea Continental Shelf Cases sets out the dual requirement for the formation of customary international law: (1) State practice (the objective element) and (2) opinio juris (the subjective element). In these cases, the Court explained the criteria necessary to establish State practice – widespread and representative participation. It highlighted that the practices of those States whose interests were specially affected by the custom were especially relevant in the formation of customary law. It also held that uniform and consistent practice was necessary to demonstrate opinio juris – opinio juris is the belief that State practice amounts to a legal obligation. The North Sea Continental Self Cases also dispelled the myth that duration of the practice (i.e. the number of years) was an essential factor in forming customary international law. 

The case involved the delimitation of the continental shelf areas in the North Sea between Germany and Denmark and Germany and Netherlands beyond the partial boundaries previously agreed upon by these States. The parties requested the Court to decide the principles and rules of international law that are applicable to the above delimitation because the parties disagreed on the applicable principles or rules of delimitation. Netherlands and Denmark relied on the principle of equidistance (the method of determining the boundaries in such a way that every point in the boundary is equidistant from the nearest points of the baselines from which the breath of the territorial sea of each State is measured). Germany sought to get a decision in favour of the notion that the delimitation of the relevant continental shelf was governed by the principle that each coastal state is entitled to a just and equitable share (hereinafter called just and equitable principle/method). Contrary to Denmark and Netherlands, Germany argued that the principle of equidistance was neither a mandatory rule in delimitation of the continental shelf nor a rule of customary international law that was binding on Germany. The Court was not asked to delimit because the parties had already agreed to delimit the continental shelf as between their countries, by agreement, after the determination of the Court on the applicable principles.

Facts of the Case:

Netherlands and Denmark had drawn partial boundary lines based on the equidistance principle (A-B and C-D). An agreement on further prolongation of the boundary proved difficult because Denmark and Netherlands wanted this prolongation to take place based on the equidistance principle (B-E and D-E) where as Germany was of the view that, together, these two boundaries would produce an inequitable result for her. Germany stated that due to its concave coastline, such a line would result in her loosing out on her share of the continental shelf based on proportionality to the length of its North Sea coastline. The Court had to decide the principles and rules of international law applicable to this delimitation. In doing so, the Court had to decide if the principles espoused by the parties were binding on the parties either through treaty law or customary international law.

Questions before the Court (as relevant to this post):

Is Germany under a legal obligation to accept the equidistance-special circumstances principle, contained in Article 6 of the Geneva Convention on the Continental Shelf of 1958, either as a customary international law rule or on the basis of the Geneva Convention?

The Court’s Decision:

The use of the equidistance method had not crystallised into customary law and the method was not obligatory for the delimitation of the areas in the North Sea related to the present proceedings.

Relevant Findings of the Court:

1. Nature of the treaty obligation: Is the 1958 Geneva Convention, and in particular Article 6, binding on Germany?

1. Article 6 of the Geneva Convention  stated that unless the parties had already agreed on a method for delimitation or unless special circumstances exist, the equidistance method would apply. Germany had signed, but not ratified, the Geneva Convention, while Netherlands and Denmark were parties to the Convention. The latter two States argued that while Germany is not a party to the Convention (not having ratified it), she was still bound by Article 6 of the Convention because:

“…(1)  by conduct, by public statements and proclamations, and in other ways, the Republic has unilaterally assumed the obligations of the Convention; or has manifested its acceptance of the conventional regime; or has recognized it as being generally applicable to the delimitation of continental shelf areas…

(2) the Federal Republic had held itself out as so assuming, accepting or recognizing, in such a manner as to cause other States, and in particular Denmark and the Netherlands, to rely on the attitude thus taken up” (the latter is called the principle of estoppel).

2. The Court rejected the first argument. It said that only a ‘very definite very consistent course of conduct on the part of a State would allow the Court to presume that the State had somehow become bound by a treaty (by a means other than in the formal manner: i.e. ratification) when the State was ‘at all times fully able and entitled to…’ accept the treaty commitments in a formal manner. The Court held that Germany had not unilaterally assumed obligations under the Convention. The court also took notice of the fact that even if Germany ratified the treaty, she had the option of entering into a reservation on Article 6, following which that particular article would no longer be applicable to Germany (in other words, even if one were to assume that Germany had intended to become a party to the Convention, it does not presuppose that it would have also undertaken those obligations contained in Article 6).

3. Note: The Vienna Convention on the Law of Treaties of 1969 (VCLT), which came into force in 1980, discusses in more detail treaty obligations of third States (those States who are not parties to the treaty). It clearly stipulates that obligations arise for third States from a provision of a treaty only if (1) the actual parties to the treaty intended the provision to create obligations for third States; and (2) third State expressly accept those obligations in writing (Article 35 of the VCLT). The VCLT was not in force when the Court deliberated on this case. However, as  seen above, the Court’s position is consistent the VCLT. (See the relevant provisions of the Vienna Convention on the Law of Treaties).

4. The Court held that the existence of a situation of estoppel would have allowed Article 6 to become binding on Germany – but held that Germany’s action did not support an argument for estoppel. The Court also held that the mere fact that Germany may not have specifically objected to the equidistance principle as contained in Article 6, is not sufficient to state that the principle is now binding upon it.

5. In conclusion, the Court held that Germany had not acted in any manner so as to incur obligations contained in Article 6 of the Geneva Convention. The equidistance–special circumstances rule was not binding on Germany by way of treaty law.

2. Nature of the customary international law obligation: Is Germany bound by the provisions of Article 6 of the Geneva Convention in so far as they reflect customary international law?

6. Netherlands and Denmark argued that Article 6 also reflected ‘the accepted rule of general international law on the subject of continental shelf delimitation’ and that it existed independently of the Convention. Therefore, they argued, Germany is bound by the subject matter of Article 6 by way of customary international law.

7. To decide if the equidistance principle bound Germany by way of customary international law, the Court examined (1) the status of the principle contained in Article 6 as it stood when the Convention was being drawn up; and (2) its status after the Convention came into force.

(a) What was the customary law status of Article 6 at the time of drafting the Convention?

8. The Court held that the principle of equidistance, as contained in Article 6 did not form a part of existing or emerging customary international law at the time of drafting the Convention. The Court supported this finding based on (1) the hesitation expressed by the drafters of the Convention, the International Law Commission, on the inclusion of Article 6 into the Convention and (2) the fact that  reservations to Article 6 was permissible under the Convention. The Court held:

“… Article 6 is one of those in respect of which, under the reservations article of the Convention (Article 12) reservations may be made by any State on signing, ratifying or acceding, – for speaking generally, it is a characteristic of purely conventional rules and obligations that, in regard to them, some faculty of making unilateral reservations may, within certain limits, be admitted; whereas this cannot be so in the case of general or customary law rules and obligations which, by their very nature, must have equal force for all members of the international community, and cannot therefore be the subject of any right of unilateral exclusion exercisable at will by any one of them in its own favor…. The normal inference would therefore be that any articles that do not figure among those excluded from the faculty of reservation under Article 12, were not regarded as declaratory of previously existing or emergent rules of law …” (see para 65 for a counter argument and the Court’s careful differentiation)

(b) Did the provisions in Article 6 on the equidistance principle attain the customary law status after the Convention came into force?

9. The Court then examined whether the rule contained in Article 6 had become customary international law after the Convention entered into force – either due the Convention itself (i.e., if enough States had ratified the Convention in a manner so as to fulfil the criteria specified below), or because of subsequent State practice (i.e. even if an adequate number of States had not ratified the Convention, one could find sufficient State practice to meet the criteria below). The Court held that Article 6 of the Convention had not attained a customary law status. (Compare the 1958 Geneva Convention with the four Geneva Conventions on 1949 relating to international humanitarian law in terms of the latter’s authority as a pronouncement of customary international law).

10. For a customary rule to emerge the Court held that it needed: (1) very widespread and representative participation in the Convention, including States whose interests were specially affected (in this case, they were coastal States) (i.e. generality); and (2) virtually uniform practice (i.e. consistent and uniform usage) undertaken in a manner that demonstrates (3) a general recognition of the rule of law or legal obligation (i.e. opinio juries). In the North Sea Continental Shelf cases the court held that the passage of a considerable period of time was unnecessary (i.e. duration) for the formation of a customary law.

Widespread and representative participation

11. The Court held that the first criteria was not met. The number of ratifications and accessions to the Convention (39 States) were not adequately representative or widespread.


12. The Court held that the duration taken for a customary law rule to emerge is not as important as widespread and representative participation, uniform usage, and the existence of an opinio juris. It held that:

“Although the passage of only a short period of time (in this case, 3 – 5 years) is not necessarily, or of itself, a bar to the formation of a new rule of customary international law on the basis of what was originally a purely conventional rule, an indispensable requirement would be that within the period in question, short though it might be, State practice, including that of States whose interests are specially affected, should have been both extensive and virtually uniform in the sense of the provision invoked and should moreover have occurred in such a way as to show a general recognition that a rule of law or legal obligation is involved.”

Opinio juris

13. Opinio juris is reflected in acts of States (Nicaragua Case) or in omissions (Lotus case), in so far as those acts or omissions were done following a belief that the said State is obligated by law to act or refrain from acting in a particular way. (For more on opinio juris click here).

14. The Court examined 15 cases where States had delimited their boundaries using the equidistance method, after the Convention came into force (paras. 75 -77). The Court concluded that even if there were some State practice in favour of the equidistance principle, the Court could not deduct the necessary opinio juris from this State practice. The North Sea Continental Shelf Cases confirmed that both State practice (the objective element) and opinio juris (the subjective element) are essential pre-requisites for the formation of a customary law rule. This is consistent with Article 38 (1) (b) of the Statute of the ICJ. The Court explained the concept of opinio juris and the difference between customs (i.e. habits) and customary law:

“Not only must the acts concerned amount to a settled practice, but they must also be such, or be carried out in such a way, as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it. The need for such a belief, i.e, the existence of a subjective element, is implicit in the very notion of the opinio juris sive necessitatis. The States concerned must therefore feel that they are conforming to what amounts to a legal obligation. The frequency, or even habitual character of the acts is not in itself enough. There are many international acts, e.g., in the field of ceremonial and protocol, which are performed almost invariably, but which are motivated only by considerations of courtesy, convenience or tradition, and not by any sense of legal duty.” (Para 77).

15.  The Court concluded that the equidistance principle was not binding on Germany by way of treaty or customary international law. In the case of the latter, the principle had not attained a customary international law status at the time of the entry into force of the Geneva Convention or thereafter. As such, the Court held that the use of the equidistance method is not obligatory for the delimitation of the areas concerned in the present proceedings.

© Ruwanthika Gunaratne at, 2008 – 2017. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner, or without attribution, is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Ruwanthika Gunaratne with appropriate and specific direction to the original content.


2.5. Who is a Persistent Objector? (Updated)

© Ruwanthika Gunaratne and Public International Law at, 2008 – present. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Ruwanthika Gunaratne and Public International Law with appropriate and specific direction to the original content.

States become parties to a treaty through consent. That is to say, States agree to be bound by treaty provisions when they ratify these treaties. States, sometimes, enter into reservations on certain provisions of the treaty with the result that they are no longer bound by those provisions or are bound to the extent accepted by the reservation.

The question whether customary international law binds states through consent is subject to academic debate. We know that the basic rule of general customary international law (as opposed to a local custom) is that it binds all States. New states are bound by old customary law, in spite of the fact that they did not consent to the custom at the time of its formation or there after. States that are silent during the formation of customary law are bound by their silence – we call this tacit acceptance or acquiescence.

States can express its intention to be bound by customary law through public declarations, much like the signature appended to treaties. They can also oppose, in a public manner, acts of another state that is contrary to an established or establishing customary law – this opposition would give justifiable reasons for other states to assume that the first state opposes the breach because it recognizes the customary law nature of the rule. Thereby, consenting to the application of the customary rule to itself.

If we work on the premise that states can consent to be bound by customary law, either in expressed or tacit manner, then we should also discuss the possibility of a state withholding consent. This is quite normal in treaty relations – a state that does not wish to be bound by the treaty (1) may refuse to ratify or accept the treaty; or (2) in the event that it is already a treaty party, it may withdraw from the treaty following the procedures established by the treaty or in international law.

In customary international law, we call a state attempts to undertake (1) above – i.e. refuse to be bound by the customary international law at its inception – a persistent objector and (2) above – i.e. refuse to be bound by customary international law after it comes into force – a subsequent objector. The difference between treaty and customary international law in this respect is that in case of (1) theoretically at least both states are said to be exempt from their respective treaty and customary international law obligations and in case** of (2) for the treaty ceased to have an effect on the party that withdraws (with the exception of continuing obligations), but, subsequent objector remains bound by the customary law principle that it seeks to reject. (**there are some doubts as to the theoretical assumption presented in point (1) as will be seen below). We will first discuss legal issues surrounding the persistent objector and then the subsequent objector.

Persistent objector

The court in the Anglo Norwegian Fisheries case held that even if a customary law rule existed (on a ten-mile rule relating to straight base-lines),

“…the ten-mile rule would appear to be inapplicable as against Norway inasmuch as she has always opposed any attempt to apply it to the Norwegian coast.”

On the other hand, in the Asylum case the court found that a state is not bound by a customary law rule when the state refrained from becoming a party to a convention that was the first to introduce the rule that had crystallized into custom.

“But even if it could be supposed that such a custom existed between certain Latin-American States only, it could not be invoked against Peru which, far from having by its attitude adhered to it, has, on the contrary, repudiated it by refraining from ratifying the Montevideo Conventions of 1933 and 1939, which were the first to include a rule concerning the qualification of the offence in matters of diplomatic asylum.”

NB: It is arguable whether this can apply as a general rule because there are many reasons that a state may refuse to sign a convention – for example, political, moral or economic reasons. We also know that the state has the option to enter into a treaty and reserve out of the objectionable treaty provision. One cannot always assume, unless the state has expressed itself on the matter, that a state refuses to sign a particular treaty because it refutes the legality of a particular provision within the treaty.

In both these cases, the court did not set out the criteria to determine if a state is a persistent objector. It did, however, allude to certain criteria in the Anglo-Norwegian fisheries case jurisprudence. The jurisprudence of the case appears to support the idea that an existing customary law rule would not apply to a state if

(1) it objected to any outside attempts to apply the rule to itself – (a) at the initial stages and (b) in a consistent manner, and

(2) if other states did not object to her resistance (read more in the case summary available here).

Commentators have stated, on the other hand, that for a state to become a persistent objector, the state must

(1) object to the practice at the initial stages of the formation of customary law and continue to object in a sustained manner; or

(2) adopt a contrary practice at the initial stages of the formation of customary law and continue to do so a sustained manner.

The objection must be expressed – either verbally or as contrary practice. There is no rule that States have to take physical action to preserve their rights (see the commentary (15) to the ILA customary law study).

Some argue that the notion of a persistent objector is a figment of the imagination of international lawyers. Curtis quotes Stein in stating that the latter’s research “failed to turn up any case where an author provided even one instance of a state claiming or granting an exemption from a rule on the basis of the persistent objector principle – excepting of course the Asylum and Fisheries cases themselves.”

The basis of a persistent objector, in academic literature, appears to be that the objecting state claims an exemption from a potential and actual rule. In the Fisheries case Norway did not claim such an exemption. Norway was clear that it was not claiming an exception to the rule (i.e. that its practice was not contrary to international law) but rather it claimed that its practice was in conformity with international law (see page 21).

 “… “The Norwegian Government does not rely upon history to justify exceptional rights, to claim areas of sea which the general law would deny; it invokes history, together with other factors, to justify the way in which it applies the general law.” …In its (Norway’s) view, these rules of international law take into account the diversity of facts and, therefore, concede that the drawing of baselines must be adapted to the special conditions obtaining in different regions. In its view, the system of delimitation applied in 1935, a system characterized by the use of straight lines, does not therefore infringe the general law; it is an adaptation rendered necessary by local conditions. ”

In other words, Norway did not plead an exemption to the general rule and the court’s finding to support this position. It is possible that Norway did not plead this exemption because it did not believe the rule to exist. For example, the Norwegian Minister of Foreign Affairs, in 1870, stated that,

“in spite of the adoption in some treaties of the quite arbitrary distance of 10 sea miles, this distance would not appear to me to have acquired the force of international law. Still less would it appear to have any foundation in reality…”

A state cannot plead for an exemption of a rule that it does not recognize to exist. Therefore, as Norway did, it would instead plead that its action is in conformity with international law.

But what if the rule had crystallized into a general customary international law rule? In this case, irrespective of the recognition of an individual state the rule would exist and the state wishing to benefit, as a persistent objector, would undoubtedly claim an exemption to the rule. In reality, there have not been cases before the international court of justice of this nature where a state claims that it is exempted from customary international law after the rule had formed.

Is it then possible to argue that the court envisaged a so-called persistent objector rule is possible only at the time of the formation of customary international law? As Charney points out, in both the Asylum and Fisheries cases, the court was dealing with a customary law whose existence was uncertain. In other words, the rule was at its initial stages where it could have or could not have evolved into a customary law.

“In fact, the two international court of justice cases which appear to support the persistent objector rule both arose in circumstances where the new rule itself was in substantial doubt. Thus, it was significantly easier for the objector to maintain its status. No case is cited for a circumstance in which the objector effectively maintained its status after the rule became well accepted in international law. In fact, it is unlikely that such a status can be maintained in light of the realities of the international legal system. This is certainly the plight that befell the US, The UK and Japan in the law of the sea. Their objections to expanded coastal state jurisdiction were ultimately to no avail, and they have been forced to accede to 12-mile territorial seas and the 200-mile exclusive economic zone.”

The absurdity of a persistent objector continuing to benefit from its objector status is demonstrated in the following examples:

(1) Consider also this possibility. A customary law rule is formed with regard to the 12-mile territorial limit within which the state’s citizens have the exclusive right to engage in fishing. If country B considers themselves as persistent objectors to this rule then it is not bound by this rule. Country B’s citizens, then in pursuance of the non-binding nature of the customary law rule on its country, ventures into country C’s territorial waters to fish. Country C can arrest these fishermen and prosecute them in accordance with its domestic laws. Country B does not have an actionable cause before an international court because country C’s action was to enforce a customary law right.

(2) The other argument is that persistent objection cannot affect or look to absolve the state’s obligations of jus cogens norms. For example, a state cannot said to have a right or escape from the prohibition of torture simply because it had been a persistent objector. This would be consistent with the position in treaty law – states cannot make treaties or treaty reservations that conflict with jus cogens norms.

But what about other fundamental norms that fall short of the jus cogens status – consider for example human rights obligations that do not form jus cogens norms. For example, in the hypothetical scenario that a state objected initially and persistently to the freedom of expression or religion, would the state, then, be excused if it violated people’s rights to freedom and religion? Or would we say that these people did not have the rights because the state chose the path of a persistent objector?

(3) What if the rule that the persistent objector objected to was an obligation? Assume for example, the hunting of a certain endangered animal is prohibited under treaty and customary law. Assume that state B had consistently objected to this prohibition and continues to hunt that animal even after the prohibition becomes a customary law right. Does this mean that state B is now absolved from the prohibition and can continue to hunt regardless of the customary law ban?

In view of the above, it maybe more prudent and practical to argue that a state can only be a persistent objector – and have the benefits of being a persistent objector – at the time of the formation of the customary law. This is also consistent with the fact that existing customary law binds new states and that they cannot withdraw from customary law after they attain statehood. The two decisions of the International Court of Justice support this view (see Charney’s views on how a persistent objector can use its status to influence the development of the law).

It goes without saying that if a number of states affected by a particular custom objects to the newly emerging customary rule this would prevent its formation or assist in the formation of a different customary law rule. The ILA customary law study states:

“As a matter of policy, the persistent objector rule could be regarded as a useful compromise. It respects States’ sovereignty and protects them from having new law imposed on them against their will by a majority; but at the same time, if the support for the new rule is sufficiently widespread, the convoy of the law’s progressive development can move forward without having to wait for the slowest vessel.”

Subsequent objector

Suffice to say, the consequences of a subsequent objector – one who objects after the formation of the customary law rule – is clear. The state that objects continues to be bound by the customary law. If it acts in contrary to the law, it violates the law. The state can be held responsible for the violation under international law.

If a number of states agree to the deviation then these states could create another customary law rule, either as a local custom or, if a sufficient number of affected states participate, a general custom.

For a subsequent objector to develop a new customary law rule an existing norm must be broken. A state wishing to change customary law must either (1) violate the law and hope other states would acquiesce to it (and if, and until such time the state would be in breach of a customary international law); or (2) without violating the existing law the state must (a) get a sufficient number of states to accept that a new customary law had developed before choosing to adopt its state practice accordingly or (2) use the existing framework and creative interpretations to bring the violation within the existing law. In time, this creative interpretation would allow for the formation of new law or it would be rejected by states preventing such formation. In this manner, at least, as Rasheed argues, the state would not have to repudiate the customary law before adopting a contrary practice.


Recommended Reading

Case law

“customary law rules . . . must have equal force for all members of the international community, and cannot therefore be the subject of any right of unilateral exclusion exercisable at will by any one of them in its own favour.” 

“Undoubtedly, no single nation can change the law of the sea. That law is of universal obligation, and no statute of one or two nations can create obligations for the world. Like all the laws of nations, it rests upon the common consent of civilized communities. It is of force, not because it was prescribed by any superior power, but because it has been generally accepted as a rule of conduct. “Whatever may have been its origin, whether in the usages of navigation or in the ordinances of maritime states, or in both, it has become the law of the sea only by the concurrent sanction of those nations who may be said to constitute the commercial world. Many of the usages which prevail, and which have the force of law, doubtless originated in the positive prescriptions of some single state, which were at first of limited effect, but which when generally accepted became of universal obligation. The Rhodian law is supposed to have been the earliest system of marine rules. It was a code for Rhodians only, but it soon became of general authority because accepted and assented to as a wise and desirable system by other maritime nations.”

The authors argue that in the past a State could unilaterally withdraw from a customary law,  if the State gave adequate notice about its intent. They call this the “Default View” of CIL. Today, unless it is a persistent objection, a State cannot unilaterally withdraw from an existing custom. This is called the “Mandatory View”. This rule apples to new States, who never even had the chance of objecting as a persistent objector. The shift from default view to mandatory view…

“[…] appears to have occurred in the late nineteenth and early twentieth centuries, at a time when imperialism was at its height and most of Asia and Africa were under the control of the European powers. The “family of nations” was being expanded, but control over law creation was still largely in the hands of the so-called “civilized” nations, which meant primarily nations in Western Europe. Viewed in this context, the Mandatory View likely evolved as part of an effort to bind new nations and former colonies to international law rules that had already been worked out by a handful of powerful states. Later, when the new entrants into the system gained strength in numbers and the former powers became concerned that they might lose control of the process of law creation in the international arena, the Mandatory View was modified to allow for opting out of a CIL rule prior to the time that it became established. This right of opt out, however, was crafted in such a way as to disallow new nations from opting out of any of the CIL rules that had developed before they came into the system.”

“There is fairly widespread agreement that, even if there is a persistent objector rule in international law, it applies only when the customary rule is in the process of emerging. It does not, therefore, benefit States which came into existence only after the rule matured, or which became involved in the activity in question only at a later stage. Still less can it be invoked by those who existed at the time and were already engaged in the activity which is the subject of the rule, but failed to object at that stage. In other words, there is no ‘subsequent objector’ rule.” 


© Ruwanthika Gunaratne and Public International Law at, 2008 – present. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Ruwanthika Gunaratne and Public International Law with appropriate and specific direction to the original content.