The legal regime of reservations has been codified in the Articles 19 to 23 of the Vienna Convention. Since this regime does not always give clear answers on how to deal with reservations, the International Law Commission (ILC) together with the international community is currently discussing "draft directives" on this issue.
One of the great difficulties is how to distinguish reservations from interpretative declarations. The Vienna Convention does not explicitely deal with the latter, but since the way a reservation is phrased or named does not matter, a large number of so-called interpretative declarations would seem to be in fact covered by the provisions of the Vienna Convention on reservations.
In the same way as reservations, interpretative declarations are unilateral acts, but unlike the former, such declarations can be made at any time whereas a reservation must be formally confirmed by the State at the time of expressing its consent to be bound by a given treaty (Article 23 (2)), viz. when ratifying, accepting or approving it.
By an interpretative declaration, a State aims at clarifying what meaning or extent it attributes to a given treaty ot to some of its provisions. The qualification of an unilateral declaration as reservation or interpretative declaration depends on the legal effects it intends to produce, a matter which is far from being always clear.
In the case of a State not qualifying itself its declaration as reservation or interpretative declaration, it is sometimes the depositary who chooses one of the two designations when communicating the declaration to the other States Parties in accodance with Article 77 (1)(e) or with any other provision of a particular treaty relevant in the given circumstances.
