Treaty law is a high specialized field of study. Technically, “the law of treaties” refers to how treaties are created, whereas “treaty law” focuses on the subject of these treaties.
Some people however, have the mistaken impression that treaties are like chain letters, that one country receives a document to sign after another one, and that everyone is referring to what has already been done elsewhere! In actual international legal theory and practice, an instrument is first drafted and adopted. If there is a signature event, it is possible that several States will sign the actual text or an instrument of approval (which has the same legal effect) on the same day, or within a short time.
Note: the definition of “chain letter” is:
Chain Letter: “A letter directing the recipient to send out multiple copies so that its circulation increases in a geometric progression as long as the instructions are carried out.” Webster’s II, New Riverside University Dictionary, 1984.
Every treaty contains a clause indicating when it enters into force, and after how many signatures. The key idea is that a single text is approved by one State after after another, with the result that a State can approve a treaty that was signed by other States 50 years before. A treaty enters into force under international when it entered into force for the States that have approved it.
The Agreement was adopted by resolution 35/552 of the General Assembly of the United Nations dated 5 December 1980. It was open for definitive signature by all States at the United Nations Headquarters in New York from 5 December 1980 to 31 December 1981.
It can be seen that the document in question was approved by a cluster of States in 1981 and that it entered into force in April 1981 because Article 7 required the approval of 10 States:
“The present Agreement shall enter into force on the date on which it shall have been signed or acceded to by ten States from more than one continent. For States signing or acceding after the entry into force, the Agreement shall enter into force upon the date of signature or accession.”
Obviously, this is not a “chain letter” with rather a well established practice by which a standardized agreement is circulated and approved either by signing of the actual text or by deposition of an instrument of approval.
In the case of EUCLID, the initial agreement (49006) entered into force upon second signature which is actually the standard and default practice, and acquired multilateral treaty status upon third signature. The updated agreement (49007) specified:
“This multilateral and open memorandum renews and updates the previous agreement already approved by 8 Participating Parties and it shall enter into force on the date of signature by two Parties.”