 Under article 36, bar graph 2 of the ICJ Statute, and I quote, the state's parties to the present statute may at any time declare that they recognize as compulsory, ipso facto and without special agreement, in relation to any other state accepting the same obligation, the jurisdiction of the court in all legal disputes concerning, a, the interpretation of a treaty, b, any question of international law, c, the existence of any fact which if established would constitute a breach of an international obligation, and d, the nature or extent of the reparation to be made for the breach of an international obligation, end of quote. The declarations by which states recognize as compulsory, the jurisdiction of the court are called optional closers. Under paragraph 4 of article 36, optional closers must be deposited with the Secretary-General of the United Nations, while declarations made under the PCIJ Statute that are still in force are deemed under paragraph 5 of article 36, are deemed to be optional closers for the purpose of the ICJ. Optional closers are a specific feature of the International Court of Justice, and previously of the Permanent Court of International Justice. They represent a compromise between a system of compulsory jurisdiction for all states borne by the statute, and a system in which being party to the statute is not sufficient to establish a system of compulsory jurisdiction, and where the consent of the disputing states is needed to confer jurisdiction to the court. Under the optional close mechanism, states are able to accept as compulsory and for themselves the jurisdiction of the court, and such acceptance is made unilaterally by a declaration, and if such unilateral declaration meets a similar declaration by another state, a jurisdictional link exists between those two states and the jurisdiction of the court will be compulsory for them. So the optional close mechanism enables states that wish a system of compulsory jurisdiction to have such a system. In a case between Spain and Canada about the arrest on the high seas of a fishing vessel flying the flag of Spain, the court elaborated on the nature of optional closes and said this, I quote, a declaration of acceptance of acceptance of the compulsory jurisdiction of the court, whether they are specified limits set to that acceptance or not, is a unilateral act of state sovereignty. At the same time it establishes a consensual bond and the potential for a jurisdictional link with the other states which have made declarations pertinent to article 36 paragraph 2 of the statute and makes a standing offer to the other state party to the statute which have not yet deposited a declaration of acceptance, end of quote. And let me elaborate a bit further on the mechanism itself. As article 36 paragraph 2 provides, an optional close is a declaration that can be made by states bound by the statute. States can make such declaration at any time, that is even long after having become bound by the statute. Such declarations are unilateral acts, they are made by each state without special agreement of any other. States may tailor their acceptance as they wish, they may accept the jurisdiction of the court for all disputes, but they may also make certain reservations in their optional closes excluding from the scope of their consent certain type of disputes. And for instance, a state may accept the jurisdiction, the compulsory jurisdiction of the court over disputes that arose after a certain date, or it may exclude from its acceptance a certain class of disputes like territorial or maritime delimitations. Or it may condition its acceptance on the unavailability of any other settlement mechanism etc. And furthermore, such unilateral declarations are made so as to recognize the jurisdiction of the court as compulsory ipso facto and the jurisdiction of the court will exist in relation to the other state accepting the same obligation. Those words are fundamental, fundamental importance because they mean that in order for the court to have jurisdiction, two optional closes must meet. The jurisdiction of the court will become compulsory for the state making the optional close, but only in relation to any other state accepting the same obligation. And jurisdiction will exist only so far as the same obligation to submit dispute to the ICJ has been accepted on both sides. And let me take an example to explain and illustrate this point. State A accepts the jurisdiction of the court for all purposes, except for instance, in relation to disputes relating to maritime delimitation. State B accepts the jurisdiction of the court without any limit or reservation. Now, State A and B are adjacent states and a dispute arises about the maritime delimitation between them. Is State B entitled to bring a case against State A at the ICJ about that maritime delimitation dispute? Well, because State A excluded maritime delimitation disputes from its unilateral acceptance of the court's jurisdiction, the answer is obvious. The court will lack jurisdiction. But what about if State A now is the claimant in that case? Could B, who is now respondent, take argument of the fact that State A had not accepted the court's jurisdiction over maritime delimitation disputes and ask the court to decline its jurisdiction? Or could State A reply that because it is the claimant, it is free not to avail itself of its own reservation that exists in its own optional clause and that by submitting its claim, it implicitly renounced to its reservation? Well, the answer to that question is to be found in the words of Article 36, paragraph 2. When two states have unilaterally accepted the jurisdiction of the court, such jurisdiction exists between them to the extent of the same obligation, accepted by both of them. In other words, and to use a math vocabulary, the jurisdiction of the court is limited to the lowest common denominator. The court's jurisdiction exists in so far as the object of the dispute falls within the optional clauses of the claimant and of the respondent. So as much as the respondent may rely on its own reservations and exclusions inserted in its own optional clause, it can also rely on those of the claimant because the jurisdiction of the court is reduced to the same obligation accepted by both parties. States are thus free to limit their unilateral acceptance of the compulsory jurisdiction of the court, that is to insert reservations in their optional clauses. And the effect of such reservations will be reciprocal in the sense that the subject matter of the dispute will have to fall within the acceptance of the court jurisdiction as expressed by both disputing states.