What Is The Theory Of Consent International Law Essay
The chief exponent of the theory of consent was Bynkershoek, which was later followed by more refinements by other jurists such as Zorn, Triepel and Anzilotti.  Bynkershoek took the position that the express or implied consent was the source of the basis of obligation in international law, and there was no room for existence of Inter- State law beyond what had been consented by them either expressly or impliedly.  According to these exponents, it is the will of the state that commands obedience both in municipal law and international law. Zorn goes to the extent of treating it as a branch of municipal law.  Triepel believed the common will of the States was the basis of the validity of international law, pointed out that it depended on the agreements between States, which included not only treaties but also custom and the common will was the only creative source of international law. 
The exponents of the doctrine of consent maintain that the will of the State is the binding force of international law, but they also put emphasis on the way the consent is expressed by the State.  The will of the State is said to be expressed in domestic law through legislation and in the case of international law through consent to international rules. The consent theory is divided into two forms, the actual consent theory and the theory of hypothetical consent.  According to some theorists international law is based on the actual consent of the States, it may be implied by way of custom or it might be expressly shown through treaties or other international agreements.  The State’s will is manifested in the form of conventional and customary rules and since they have consented to them, the rules are binding upon them, and nothing can be law to which they have not consented. 
According to Oppenheim “common consent" is the basis of international law as a legal system.  The common consent to internationally valid rules regarding important matters such as international civil aviation, the use of international water bodies is a necessity. This common consent cannot mean that all states must at all times expressly consent to every part of the body of rules constituting international law, since such common consent can never be established.  The membership of the international community is constantly changing: new states are formed and they join the international. Dissent of a particular from a particular rule is not to be taken as a withdrawal of consent to the system as a whole.
The common consent that is meant is thus not consent to particular rules but to the express or tacit consent of states to the body of rules comprising international law as a whole at any particular point of time. Thus new states which come into existence and become members of the international community are subject to the body of rules for international conduct in force at the time of their admission.  No single state can say on its admittance into the community of nations that it will be bound by Rule x of international law and not by Rule Y. Their admission into the international community is based on their acceptance to all the rules In force except the ones which are binding on states who are party to some treaty.
According to Jellinek, the rules of international law derive their binding force because the State consents to the limitations on its sovereignty. However though consent can easily be discerned for conventional rules, it is difficult to do so with customary rules.  To this, positivists attribute ‘tacit" or “implied" consent, i.e. the states acquiescing to customary rules. They admit that sometimes it is impossible to find any express consent in treaties, state papers, public documents, diplomatic notes, or the like to be bound by particular customary rules. They therefore consistently with their consensual theory, argue that in such exceptional cases the consent must be regarded as being ‘implied" or ‘tacit". They observe that the membership of the society of States involves an implied consent to the established rules of customary international law. Such general implied consent could only be conditioned by some fundamental rule of international law itself, and it would be still necessary to explain the source and origin of this fundamental rule. 
According to Anzilotti  , a prominent positivist, the principle of pacta sunt servanda(i.e. the agreements between states are to be respected) is the fundamental norm and an absolute postulate of international legal system from which the international law derives its binding force and authority.  This has now been codified in Article 26 of the Vienna Convention of the Law of treaties, 1969. Article 2 provides that every treaty in force is binding upon the parties to it and must be performed by them in good faith. Anzilotti holds that just as in the case of treaties, customary rules are based on the consent of states and there is an implied agreement. The main defect in this analysis is that the norm pacta sunt servanda is only partially an explanation of the binding force of international law. Anzilotti’s views that customary rules are binding on the state’s by virtue of an implied pactum is no more convincing than the “tacit" consent argument of other positivists. It has been rightly observed by Gihl ,’ the realisation that international customary law does not rest on a agreement and that the tenet pacta sunt servanda is itself a rule of customary law led to a new formulation of the basic norms.’ 
THEORY OF AUTO-LIMITATION
Having come to the conclusion that States do observe international law and will violate it on an issue which is vital to their interest, the question arises as to the basis of obligation in international law.  The nineteenth century with its business oriented philosophy stressed the importance of the contract, as the legal basis of an agreement freely entered into by both sides, and this influenced the theory of consent in international law.  States were independent, and free agents, and accordingly they could be bound by their own consent. There was no authority in existence able theoretically or practically to impose rules amongst the various member states. The approach found its extreme expression in the theory of auto limitation, or self limitation which declared that states could only be obliged to comply with international legal rules if they had first agreed to be obliged.  The rules of international law are adopted to the extent when the states have voluntarily restricted their sovereignty. The sovereignty is absolute is absolute in so far as a State agrees to its limitation. Thus a state has freedom of action, except in so far as it has agreed to the rules restricting that freedom.
CRITICISMS OF THE THEORY OF AUTO LIMITATION
However the theory maybe criticised on the following grounds. In the first place the theory is based on a pre supposition that there exists a State will which is nothing but the will of the people. It does not explain the fact. For example, when the a treaty has been ratified by say Great Britain, we can if we like say that the ratification is an expression of Great Britain’s will to become bound by a treaty. This language however is very alluring and figurative, merely describes a situation of fact, that the British executive organ has ratified the treaty, and that the British people through their representatives have become responsible for their fulfilment of treaty obligations. The state will is therefore a mere falcon de parler, as the only will or wills which operate are those of the individuals who govern Great Britain. Secondly auto limitation is no limitation at all. It implies that the state can free itself from self imposed restriction, but in practice this is not possible. Thirdly, the theory has been criticised by Brierly, Friedmann and other jurists on the ground that the theory completely fails to explain how it is known that a state can only be bound by self imposed obligations or why this theory of sovereignty should be accepted in advance of proper examination of the actual character of international law. Besides there is some incoherence in the argument to show that states, because their sovereignty, can only be subject to be bound by rules which they have imposed upon themselves.
CRITICISMS OF THE THEORY OF CONSENT
The basis of international law on the theory of common consent of the States can be assailed on grounds more than one. Several objection have been raised against it, the prominent ones amongst them are:
Treaties and custom are no longer considered to be the only sources of international law. Art 38(1)(c) of the Statute of the International Court of Justice accepts the “general principles of law recognised by civilised nations" as a source of international law. This helps the judges to develop the content of international law. This shows us that consent is always not necessary for international law to become functional.
The theory of consent is also not fully applicable in case of treaties. Dispositive treaties are examples of treaties which are binding on the states without their consent. a striking example is paragraph 6 of Article 2 of the United Nations Charter, which provides that the United nations is to ensure that non member states shall act in accordance with the principles of the Charter so far as may be necessary for the maintenance of international peace and security. 
It is difficult to reconcile the facts with a consensual theory of international law. In the case of customary rules, there are many instances where it is quite impossible to find any consent by states to the binding effect of these rules. Moreover, the consensual theory breaks down in the crucial case of a new state admitted to the family of nations, as for example Kazakhstan which was earlier a part of the Soviet Union did not consent to its international commitments which were binding on it at the time of its birth.  Such a new state is bound by international law from the date of its emancipation without an express act of consent. The idea that in such an instance there is a “tacit" or implied consent, merely strains the facts. The reality is that other states look to the new state to comply with the whole body of international law. This has consistently been the attitude of two influential Great powers, the United States of America  and Great Britain  .
One of the major defects of the consent theory is that it can be used to justify the withdrawal of consent from a rule. The question to be asked at this juncture is whether by withdrawing consent, can a State eliminate its international obligations? According to Brierly, a State cannot deny that it has violated international law when it does not act in accordance with a treaty which it had concluded. But if the treaty was said to be no longer binding after withdrawal of, it would lead to the conclusion that a state can by its unilateral act enforce its unconditional right to relieve itself from any obligation which it was bound under the treaty. Thus the State would not be under any obligation because the consent which was the source of the obligation had been withdrawn. As Brierly comments, a consistently consensual theory would have to admit that if the consent is withdrawn, the obligation created by it comes to an end. 
According to Westlake:
“It is enough to show that the general consensus of opinion within the limits of the European civilisation is in favour of the rule"
Thus the test which is to be applied is whether the rule is one which is generally recognised by the society of nations. Thus it is not necessary when invoking a particular rule of international law against a particular state to show that the state has assented to it diplomatically.
These objections to the theory of consent are by no means exhaustive, but they prove to illustrate the main defect of the theory which lies in the fallacy of the belief that there has to be consent amongst the States for international law to operate. In spite of its many weaknesses, the consensual theory has had one very valuable influence on the science of international law. It has concentrated attention on the actual practice of states by emphasising, perhaps unduly, that only those rules which states do in fact observe can be rules of international law. It is because of its consensual basis and its wide acceptance in the International community that international law can be equated with State law and that is the main reason why it is challenged. Without any community interest and the general consent of the application of rules, international law would have no function.  The International Court of justice also took support of this theory while delivering judgements in the Asylum Case  , the Anglo-Norwegian Case  and the US Nationals in Morocco case  .  This has led to a more realistic outlook in the works of international law, and to the elimination of much that was academic, sterile and doctrinal.
States obey international law due to a variety of factors. It cannot be said that the true basis of international law lies neither in the consent amongst states nor exclusively in natural law.  It is mainly due to their “self interest" that States obey international law. A state recognizes the fact that it is better to obey international law rather than to lose all the advantages gained from it. Thus in cases where there are reciprocal benefits in question, a State will hesitate to break the law.  Thus most rules in international law are based on identical or reciprocal benefits of both the nations. Thus “self interest" seems to be the basis for compliance with international law. In Lissttzyn’s views, there are three reasons for obeying the law: self interest, sense of moral obligation and habit.  Man as a reasonable human being will obey international law as long as it is in his self interest.