 In this video, I would like to add a few points in relation to the creation of customer international law. All those points relate to the generality of practice, and hence to the personal scope of custom. We have seen that the practice of states must be general. It must both be settled and shared by the states that are specially affected by the emerging rule. In that sense, because it is based on what states actually do and on their opinion, or jurists about it, customer international law is somehow based on a form of tacit consent by the practicing states and also on acquiescence by the other states. Well, this raises difficult theoretical debates in which I do not want to enter into here, but let us admit for a moment the idea of custom being ultimately explained by a form of consent. If that is the case, then three problems may arise. And the first problem is as follows. Is it possible for a customary rule to emerge if one state objects to the practice of the other states? In order to answer that question, two situations must be distinguished. In the first situation, the objecting state is powerful and influential enough to induce the other states to stop behaving as they once or twice did. The practice will quickly stop, the opinion of jurists will not be expressed, and as a result, no customary rule will emerge. In the second situation, the objecting state is not in a position to stop the practice of the other states, but it constantly objects to such practice. Each time the other states act, it reacts and objects to that practice. The practice will lack a certain generality because the persistent objecter does not share it, but it will nevertheless be generally enough, when sustained by corresponding general opinionaries, to result in the creation of a new rule of customary international law. However, because that state has, all along, expressed its disagreement with the settled practice of the other states, it is admitted that it will not be bound by the new custom. And this is called the persistent objecter principle in the formation of customary rules, and as a possibility, it has been accepted by the ICJ back in 1951 in the Anglo-Norwegian Fisheries case. It reflects a voluntary and constant based conception of the formation of international law, even of customary international law. And in contrast to that constant based approach, the second problem I would like to quickly address is the one relating to new states. When a new state comes to existence, it is usually admitted and assumed that it is immediately bound by all existing rules of customary international law. The new state does not need to express any consent in that regard, but neither can it start to object to those existing rules. The persistent objecter principle only applies if the objection is made from the inception of custom, not after the custom has been established. So the new state is not born in a legal vacuum. It is at least bound by existing customary rules. That is to say rules that did not emerge through its practice and its opinionaries, not even by its acquiescence. And the new state cannot escape or opt out from existing customary rules. That situation proves that the constant based approach cannot explain everything and is not absolute. Therefore, one must admit that the binding character of customary law rests also on some sociological necessities rather than on pure volunterism. And the third problem I would like to mention is perfectly compatible, both with a constant based approach of customary law and a more sociological approach to it. It is the phenomenon of regional or local customs. In derogation to the idea that international customs are binding on all states, it is accepted that some customs may be binding only for a certain group of states in a specific region of the world or even locally on two or three states. In 1950, in a case between Columbia and Peru about diplomatic asylum, the court did not rule out the idea of a regional custom, but it considered that Columbia had not sufficiently proved that there existed a Latin American custom on granting diplomatic asylum. Ten years later, in 1960, in the case of the right of passage over Indian territory, the court ruled that there was a local custom allowing for the existence of such a right of passage in favor of Portuguese enclaves in India. There is no need to delve into those cases, but I cannot fail to bring to your attention a certain paradox, and the paradox is as follows. The more local or regional an alleged customary rule is, the higher the standard of proof will be required in the sense that the practice and opinionaries of the concerned states will be closely scrutinized so as to be sure that the practice has been duly accepted as law by them. And in contrast to this, the standard of proof required when an alleged general custom is at stake will be paradoxically not as high and demanding. Most of the time it will be sufficient to refer to the practice and opinionaries of some states, the practice of which will be more apparent, while some acquiescence on the part of the other states will be deduced, absent any objection from them.