Time is an important element in the process of reservations to treaties and, consequently, in the legal regime established by the Vienna Conventions for reservations and reactions thereto. The very definition of reservations, embodied in article 2(1)(d) of the 1969 and 1986 Vienna Conventions, as well as in article 2(1)(j) of the 1978 Vienna Convention, and included in the definition adopted by the International Law Commission in its Guide to practice, includes precise indications and limits concerning the moment in time for a reservation to be formulated. In practice however, reservations have been and are made before and after this peculiar moment. To some extent, the work of the International Law Commission has shown that these are still reservations, even if they are not contemplated by the Vienna regime. But they can nevertheless deploy their purported effects under some additional conditions. The same holds true with regard to objections to reservations which can be formulated prematurely or late. They are still objections even if their concrete legal effects might be affected. Whereas time is important for the legal consequences attached to reservations and reactions thereto, it plays a less important role in the overall process of reservations dialogue.

*Please note: This paper was published in the European Journal of International Law, Volume 24, issue 4. It can be found on the EJIL website.