The Role of Subsequent Practice in the Interpretation of Constituent Treaties of International Organizations

According to common Articles 31 and 32 of the 1969 Vienna Convention on the Law of Treaties and the 1986 Vienna Convention on the Law of Treaties between States and International Organizations, subsequent practice of the parties to a treaty is an authentic element in the interpretation of that treaty; whether it is a mere inter-state treaty or a constituent treaty of an international organization. Because of the growth and development in the life of an IO and originating from its subsequent practice, the constituent treaty of that organization entails a modern reading. Directing an IO in a legal and desirable way is based on Constituent treaty of that organization. To the same extent, this role can and should be expected from the organization's own subsequent practice. Legal precedent, ILC findings and legal doctrine confirm this effect. Examination the role of subsequent practice by IO's organs and practice followed by the parties of the constituent treaties of international organizations in the interpretation of that treaty, is this paper's purpose.