Most declarations contain political statements only and thus have no binding effect in international law.
Sometimes states make «declarations» as to their understanding of some matter or as to the interpretation of a particular provision. Unlike reservations, declarations merely clarify the state’s position and do not purport to exclude or modify the legal effect of a treaty. Usually, declarations are made at the time of the deposit of the corresponding instrument or at the time of signature.
The term «declaration» is used for various international instruments. However, declarations are not always legally binding. The term is often deliberately chosen to indicate that the parties do not intend to create binding obligations but merely want to declare certain aspirations. An example is the 1992 Rio Declaration. Declarations can however also be treaties in the generic sense intended to be binding at international law. It is therefore necessary to establish in each individual case whether the parties intended to create binding obligations. Ascertaining the intention of the parties can often be a difficult task. Some instruments entitled «declarations» were not originally intended to have binding force, but their provisions may have reflected customary international law or may have gained binding character as customary law at a later stage. Such was the case with the 1948 Universal Declaration of Human Rights. Declarations that are intended to have binding effects could be classified as follows:
- A declaration can be a treaty in the proper sense. A significant example is the Joint Declaration between the United Kingdom and China on the Question of Hong Kong of 1984.
- An interpretative declaration is an instrument that is annexed to a treaty with the goal of interpreting or explaining the provisions of the latter.
- A declaration can also be an informal agreement with respect to a matter of minor importance.
- A series of unilateral declarations can constitute binding agreements. A typical example are declarations under the Optional Clause of the Statute of the International Court of Justice that create legal bonds between the declarants, although not directly addressed to each other. Another example is the unilateral Declaration on the Suez Canal and the arrangements for its operation issued by Egypt in 1957 which was considered to be an engagement of an international character.