The article offers an overview on the forms and contents of the declarations accepting the compulsory jurisdiction of the ICJ made under Article 36. para. 2. of the Statute. The author examines first the provisions of the Statutes of the two world courts, than the forms of declarations and the practice of the two International Courts on the validity and the entry into force of the declarations accepting the compulsory jurisdiction. Since the states are free to choose what form they please one can find a great variety of the forms and wording of the declarations. According to the Statute the only formality required is that a declaration should be deposited to the UN Secretary General and the intention of the state clearly results from a declaration. The ICJ dealt in several cases with the problem of the entry into force of the declarations and according to the well-established practice of the Court the data of the entry into force of these instruments corresponds to their deposit to the Secretary General.
The paper analyses the role and importance of the principle of reciprocity in the optional clause system of the International Court of Justice. After a short description of the Statute provisions on reciprocity of the two International Courts the author deals with the stipulation of reciprocity in declarations accepting the compulsory jurisdiction of the Court. The main part of the paper is devoted to the legal practice of the two International Courts on the matters of reciprocity. As a conclusion the author says that, by virtue of the principle of reciprocity, reservations to the acceptances of compulsory jurisdiction tend, in practice, to make their effect felt more often than not, precisely against the State or States making a reservation.