 In the previous video, the notion of reservation was introduced, as well as the basic conditions for making reservations. Article 19 of the Vienna Convention states other limits to the possibility of making reservations. First, and quite obviously, reservations cannot be made if they are prohibited by the treaty. For instance, Article 120 of the Rome Statute of the International Criminal Court simply states, I quote, no reservations may be made to this statute, end of quote. Second, if the treaty provides that only specified reservations may be made, any other reservation is prohibited and does not produce any effect. Third, in all other cases, the reservation must not be, I quote, incompatible with the object and purpose of the treaty, end of quote. This criterion comes from the advisory opinion delivered by the International Court of Justice in 1951 concerning the reservations to the Convention on the Prevention and Punishment of the Crime of Genocide. You may recall that the notion of the object and purpose of the treaty already appears in Article 18 of the Vienna Convention in relation to the interim obligation that exists pending the entry into force of the treaty. The idea here is the same, a reservation is not permissible if it contradicts the very raison d'être of the treaty, that is, the core obligations under the treaty. For instance, if a state adheres to the genocide convention, while at the same time declaring that it does not consider itself bound by the convention in relation to a specific ethnic group living on its territory, such declaration would obviously have to be considered as prohibited reservation. But if that is the case, what happens? Is the state bound by the entirety of the treaty, despite its prohibited reservation, or must one consider that it is not bound by the treaty at all, because its reservation, despite being invalid, was an essential element of its consent to the treaty? The first issue to be addressed is to determine who is entitled to authoritatively decide on the validity of the reservation, on its compatibility or incompatibility with the object and purpose of the treaty. If there is an international court or arbitral tribunal having jurisdiction between the parties to decide on this issue, that court or tribunal could settle the dispute about the validity of the reservation. And in case the reservation is considered to be incompatible with the object and purpose of the treaty, the same court or tribunal could also decide on the consequences of such finding. In the Bellilos case, the European Court of Human Rights decided in 1988 that an interpretive declaration made by Switzerland about Article 6, 6 of the European Convention, Article 6 is about the right to a fair trial, that such declaration was actually a reservation and that it was incompatible with the object and purpose of the Convention. And furthermore, the European Court decided to set aside that invalid reservation and it ruled that Switzerland remained nevertheless bound by the European Convention in its entirety, including Article 6. Human rights bodies usually follow such approach and it is quite understandable in light of the nature of the rights at stake. But it is not certain that a similar approach is granted, in every case, when the instrument at stake is about something else than the protection of human rights. When it is a purely contractual matter between states, the logic of consent as the basis for the creation of international law rules should maybe lead to consider that if the reservation is invalid, but was nevertheless an essential element of the state consent to the treaty, such consent has not been properly given so that the state is not bound by the treaty as a whole. Well be that as it may, and in the absence of any adjudicative body having jurisdiction to decide on the matter, the question of the validity of certain reservations will often be left to the appraisal of each of the other contracting parties. In that regard, the Vienna Convention provides for a complex system of acceptance and objection to reservations. And this is what we are going to study in the next videos.