Treaties, States Parties and Commentaries
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Commentary of 2016 
Testimonium and signature clause
Text of the testimonium and signature clause
IN WITNESS WHEREOF the undersigned, having deposited their respective full powers, have signed the present Convention.
DONE at Geneva this twelfth day of August 1949, in the English and French languages. The original shall be deposited in the Archives of the Swiss Confederation. The Swiss Federal Council shall transmit certified copies thereof to each of the signatory and acceding States.
Reservations or declarations

A. Introduction
3317  The Convention’s ‘testimonium’, beginning by the specific formulation ‘in witness whereof’, provides that, in order to sign the Convention in the name of a State, the representative of that State has to have deposited full powers.[1]
3318  The signature clause contains the place and date of the adoption of the Convention and recalls its authentic languages.[2] It furthermore specifies the tasks of the depositary relating to the conservation of the original of the Convention and the delivery of the certified true copies.
3319  Both sentences, placed at the very end of the Convention after the last article and before the signatures, were adopted by the Plenary of the 1949 Diplomatic Conference after only minor wording changes implemented during the Joint, Special and Drafting committees.[3]
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B. Testimonium and signature clause
1. Full powers
3320  According to customary international law, as codified by the 1969 Vienna Convention on the Law of Treaties, only heads of State, heads of government and ministers for foreign affairs are ex officio considered as representing their State for the purpose of performing all acts relating to the conclusion of a treaty, including signature.[4] All other representatives desiring to sign a treaty in the name of a State normally have to produce full powers.[5] The Convention’s testimonium reflects this. The original of the full powers deposited by the State’s representative and collected by the depositary at the occasion of every signature is kept with the original of the Convention in the Swiss Federal Archives. At the time, it was usual to specify the very place of filing of the original treaties. Therefore, as did other treaties at that time, the 1949 Conventions mention the Swiss Federal Archives, where all treaties deposited with the Swiss Federal Council are in principle to be found.
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2. Certified copies
3321  The original of the Convention, as happens with multilateral treaties in general, is established in just one signed document grouping all its authentic language versions. Thus, the depositary has to deliver a certified copy of the said original to each of the ‘signatory and acceding States’. The main purpose of the certified copy is to allow these States to submit the treaty to their competent internal authorities for approval before the treaty is ratified or its accession notified.
3322  A certified copy has to reproduce faithfully and in full the provisions of the original. Usually, at the end of the text of the copy, a representative of the depositary signs a dated statement certifying that the foregoing text is a true copy of the Convention. At the time of the adoption of the 1949 Conventions, the certified copy used to include the Final Act of the conference that adopted the treaty. Consequently, the Swiss Federal Council formally delivered certified copies of the Final Act of the Diplomatic Conference of Geneva, to which the texts of the Conventions were attached. According to the more recent practice of depositaries, only the text of a convention, with or without the signatures, is nowadays reproduced in the certified copy.[6]
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Select bibliography
Aust, Anthony, Modern Treaty Law and Practice, 3rd edition, Cambridge University Press, 2013, pp. 381–383 (Testimonium).
United Nations, Office of Legal Affairs, Treaty Section, Summary of practice of the Secretary-General as depositary of multilateral treaties, UN Doc. ST/LEG/7/Rev.l, United Nations, New York, 1999, paras 63–72 (Certified copies).
Villiger, Mark E., Commentary on the 1969 Vienna Convention on the Law of Treaties, Martinus Nijhoff Publishers, Leiden, 2009.

1 - For the authorization to sign and the effect of such signature, see the commentary on Article 56, sections C.2 and C.3.
2 - On authentic languages, see Article 55.
3 - Final Record of the Diplomatic Conference of Geneva of 1949, Vol. II-B, pp. 30 (Joint Committee), 73, 114 (Special Committee), 163, 170, 186 (Drafting Committee) and 373 (23rd Plenary Meeting of the Conference).
4 - See Vienna Convention on the Law of Treaties (1969), Article 7(2), which accurately reflects customary international law (Villiger, p. 146).
5 - See Vienna Convention on the Law of Treaties (1969), Article 7(1), which accurately reflects customary international law (Villiger, p. 146). Article 2(1)(c) of the Vienna Convention defines ‘full powers’ as: ‘a document emanating from the competent authority of a State designating a person or persons to represent the State for negotiating, adopting or authenticating the text of a treaty, for expressing the consent of the State to be bound by a treaty, or for accomplishing any other act with respect to a treaty’.
6 - United Nations, Summary of practice of the Secretary-General as depositary of multilateral treaties, paras 63–64.