Articles 19–23—Subsequent developments

CONTENTS
	Paras.
A. Introduction .....................................................................................	1
B. Matters not Dealt With ..................................................................	2
C. Proposals for Amendment, in Particular Within the ILC ............	3
D. Customary Basis of Articles 19–23 ..................................................	6
E. Appreciation .......................................................................................	8
F. Appendix: ILC Guidelines ..................................................................	11
Selected Literature: see the literature mentioned in Article 19.

A.INTRODUCTION

1 This Section examines issues arising in the context of all five articles, in particular matters not dealt with (N. 2), the proposals for amendment (N. 3–5), the customary basis of Articles 19–23 (N. 6–7), and also the appreciation of the provisions as a whole (N. 8). There follows an Appendix with the Guidelines prepared by the ILC since 1993 on reservations (N. 11).

B.MATTERS NOT DEALT WITH

2Articles 19–23 have been criticised for failing to cover various aspects of the reservations to treaties. Two such areas frequently mentioned are human rights treaties,1 and the legal e ects of reservations which are incompatible within the meaning of Article 19, para. (c) (q.v., N. 12–14). Further points concern the e ects of reservations to declaratory treaty rules (see Issues of Customary International Law, N. 36–42) and to treaty rules containing jus cogens (Article 53, N. 23).2

1 Interestingly, when Sir Humphrey Waldock acted as Special Rapporteur on the law of treaties in the ILC (History of the Convention, N. 5–12), he was also President of the

then European Commission of Human Rights in Strasbourg.

2 See extensively the “brief inventory” of the various problems in Pellet Report I, YBILC

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In respect of human rights treaties, Giegerich has summarised the di culties which
have arisen with States making far reaching reservations and concomitant objections
thereto. In particular, issues arise as to the standards for determining the admissibility
of reservations to such conventions, and the consequences of invalid reservations.
Further di culties concern, for instance, who should decide on the admissibility,
validity and possibly severability of reservations to such treaties, and in particular
whether these duties should fall to a supervisory body.3
More generally, it has been criticised that the Convention has failed to address the
legal e ects of inadmissible reservations4 and that it says too little on the incompat-
ibility with a treaty’s object and purpose within the meaning of Article 19, para. (c)
(q.v., N. 12–14).5

C. PROPOSALS FOR AMENDMENT, IN PARTICULAR WITHIN THE ILC
Since 1993 the ILC has examined “reservations to treaties” as a separate			3
topic.6 Its scope of examination goes well beyond Articles 19–23 and
includes international organisations and also interpretative declarations.7
Faced with choosing a method of codification, the ILC decided at least for
the time being to accomplish its work by means of a code, in particular a
set of Guidelines (N. 11, Appendix).8
	Had the ILC instead prepared a new convention on reservations which would have
	come to stand alongside the existing Articles 19–23, considerable confusion would
	have arisen, if States had been confronted with the two parallel conventions. Possibly,
	once the Guidelines have been completed, they could usefully be “promulgated” by
	means of a UN General Assembly Resolution.
It transpires from the Guidelines that they do not call in question Articles			4
19–23. Rather, they aim at complementing them and at covering areas
which are not dealt with by the Convention (N. 2). However, the Guide-
lines and their commentaries do not always make it entirely clear (N. 9)
	1995 II/1. In respect of the consolidated list of problems prepared by the ILC in
	1997, YBILC 1997 II/2 56 f and 178, Aust, Modern Treaty Law 161, considers “these
	points . . . useful, but [they] leave many questions unanswered”.
3 Extensively on this Giegerich, EPIL 4 (2000) 968 . There is a vast literature on the
	subject; for a selection of titles, see Selected Literature in Article 19.
4	Redgwell, BYBIL 64 (1993) 262; Cede, European Responses 23 ; see ibid. 24 (“fuzzy
	state of international law on reservations”).
5	Hilpold AVR 43 (1996) 378.
6	See the brief summaries in Giegerich, EPIL 4 (2000) 975 f; Hilpold, ibid. 379.
7	See M.M. Matheson, The Fifty-Eighth Session of the International Law Commission,
	AJIL 101 (2007) 435 (“[t]he guidelines adopted up to this point tend to be highly
	technical and most are of primary interest to treaty specialists in foreign ministries”).

8See Issues of Customary International Law, N. 21–27; the discussion in Villiger, Customary International Law N. 139 .

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which provisions stem directly or in modified form from Articles 19–23 and which are new or partly new.9

5There follows a brief survey of the work of the ILC on these Guidelines.10

In 1993 the ILC, on the basis of the recommendation of a Working Group on the long-term program of work, decided to include in its agenda the topic: “The law and practice relating to reservations to treaties”. The Commission noted that the 1969 Convention, the 1978 Vienna Convention on Succession of States in Respect of Treaties and the 1986 Vienna Convention on the Law of Treaties between States and International Organisations or between International Organisations set out some principles concerning reservations to treaties, but they did so in terms which were too general to act as a guide for State practice and left a number of important matters in the dark. In the ILC’s view, these conventions provided ambiguous answers to the questions of di erentiating between reservations and declarations of interpretation, the scope of declarations of interpretation, the validity of reservations, and the regime of objections to reservations, in particular, the admissibility and scope of objections to a reservation which was neither prohibited by the treaty nor contrary to its object and purpose. The Convention was also silent on the e ect of reservations on the entry into force of treaties, problems pertaining to the particular object of some treaties, in particular the constituent instruments of international organisations and human rights treaties, and reservations to codification treaties. The ILC recognised the need not to challenge the regime established in Articles 19–23, but nonetheless considered that these provisions could be clarified and developed.11

The General Assembly endorsed the ILC’s decision on the understanding that the final form to be given to the work on the topic would be decided after it was presented with a preliminary study.12

In 1994 the ILC appointed Mr. A. Pellet as Special Rapporteur for the topic.13

In 1995 the ILC considered Pellet Report I which provided a detailed study of the Commission’s previous work on reservations and its outcome. It also prepared an inventory of the problems, including those relating to the ambiguities and gaps in Articles 19–23. It was agreed that the title of the topic should read “Reservations to treaties”; that the form of the results of the study should be guidelines for the practice of States in respect of reservations; and that there should be no change in the relevant provisions of the Vienna Conventions.14

9To take but one example: Guideline 2.8.2. of Pellet Report XII on the Tacit Acceptance of a Reservation Requiring Unanimous Acceptance by the Other States and International

Organisations, YBILC 2007 II/2 37 at n. 47, and Article 20, para. 5 (q.v., N. 17).

10T his summary is taken from the various YBILCs; from The Work of the International Law Commission, 6th ed. (2004); and from http://untreaty.un.org/ilc/summaries/1_8.htm (website visited on 1 January 2008).

11YBILC 1993 II/2 95, paras. 427–430 and 440.

12Resolution 48/31 of 9 December 1993.

13YBILC 1994 II/2 179, para. 381.

14YBILC 1995 II/2 107 f, paras. 487 .

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In 1996 the ILC examined Pellet Report II. The latter submitted that despite the diversity of treaties, the Convention regime on reservations was generally applicable. Moreover, the coexistence of monitoring mechanisms did not preclude monitoring bodies from making determinations of the permissibility of reservations, even if States could still draw any consequences they wished from such determinations and react accordingly. The ILC did not have time to consider the topic and deferred the debate to its next session.15

In 1997 the ILC, on the basis of Pellet Report II, reached some preliminary conclusions and invited Governments to comment thereupon.16

In 1998 the ILC considered part of Pellet Report III dealing with the definition of reservations and interpretative declarations to treaties, and adopted seven Guidelines.17

In 1999 the ILC discussed the remainder of Pellet Report III and also Pellet Report IV on further issues, such as the definition of reservations and interpretative declarations, and adopted 18 Guidelines.18

In 2000 the ILC reviewed part of Pellet Report V on alternatives to reservations as well as on the procedure regarding reservations, and adopted five Guidelines.19

In 2001 the ILC examined further parts of Pellet Report V relating to questions of procedure regarding reservations and interpretative declarations, and adopted twelve Guidelines. The ILC also had before it Pellet Report VI relating to the modalities of formulating reservations and interpretative declarations as well as the publicity of reservations and interpretative declarations.20

In 2002 the ILC adopted eleven Guidelines on the basis of Pellet Report VII on the formulation, modifi cation and withdrawal of reservations and interpretative declarations.21

In 2003 the ILC discussed Pellet Report VIII on the withdrawal and modification of reservations and interpretative declarations as well as on the formulation of objections to reservations and interpretative declarations, and adopted eleven Guidelines.22

In 2004 the ILC reviewed Pellet Report IX, inter alia, on the definition of objections to reservations, and adopted five Guidelines.23

In 2005 the ILC was confronted with the first part of Pellet Report X concerning, inter alia, the freedom to formulate reservations, reservations expressly prohibited by the treaty, and various issues of specified reservations. It adopted four Guidelines.24

15YBILC 1996 II/2 83, para. 137.

16YBILC 1997 II/2 56 f, para. 28 and 157.

17YBILC 1998 II/2 90 , paras. 479 ; the Guidelines are ibid. 99 .

18YBILC 1999 II/2 91 , paras. 468 .

19YBILC 2000 II/2 102 , paras. 636 ; the Guidelines are ibid. 106 .

20YBILC 2001 II/2 440 , paras. 113 f, the Guidelines are ibid. 145 .

21YBILC 2002 II/2 28, paras. 50 f; the Guidelines are ibid. 50 .

22YBILC 2003 II/2 153, 329 f; the Guidelines are ibid. 165 .

23YBILC 2004 II/2 239 f, paras. 266 ; the Guidelines are ibid. 246 .

24YBILC 2005 II/2 142 , paras. 343 ; the Guidelines are at ibid. 162 .

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In 2006 the ILC studied the remainder of Pellet Report X on the validity of reservations and the concept of a treaty’s object and purpose, and it adopted six guidelines. It also had before it Pellet Report XI.25

In 2007 the ILC discussed on the basis of Pellet Reports XI and XII issues of the object and purpose of treaties, vague reservations, and reservations to provisions reflecting customary norms and jus cogens.26

Pellet Report XIII on the validity of reservations will be discussed by the ILC in 2008. Pellet Report XIV should be submitted in 2009, and in 2010–2011 Pellet Reports XV and XVI are intended to consider the observations from Governments on the Guidelines.27

D. CUSTOMARY BASIS OF ARTICLES 19–23

6Di erent views have been expressed on the declaratory nature of Articles 19–23.

For instance, Sir Humphrey Waldock observed as Expert Consultant in Vienna in respect of the principle of Article 19, para. (c) that “the debate seemed to have shown that the principle of that criterion now met with very general acceptance”.28 T he

Swiss Federal Tribunal viewed Article 20, para. 1 as an established rule of customary international law.29 Kühner agrees herewith; he also sees a customary core in Article 20, para. 2, but not in para. 3.30 Article 20, para. 5 has been considered as constituting progressive development.31 As regards Article 21, the ILC Report 1966 found that these rules “appear not to be questioned”.32 Article 21, para. 3 was applied qua customary law by the Tribunal in the Continental Shelf Arbitration (UK/France) (N. 8).33 Article 22, subpara. 3(a) was viewed by the Court in the Armed Activities on the Territory of the Congo (Democratic Republic of the Congo/Rwanda) Case as amounting to a “rule of international law”.34 Generally, the Swiss delegation stated in Vienna in 1968 that in its view the “[t]he flexibility of the [ILC’s] system was . . . in conformity with the present trend of international law”).35

25YBILC 2006 II/2 295 , paras. 101 ; the Guidelines are ibid. 306 .

26YBILC 2007 II/2 15 , paras. 34 ; the Guidelines are ibid. 66 .

27ILC Report 2007, YBILC 2007 II/2 232.

28OR 1968 CoW 126, para. 7.

29Arrêts du Tribunal Fédéral 110 Ib 395.

30Vorbehalte, 159, 166 ad 175.

31Aust, Modern Treaty Law 153; Treviranus, GYBIL 25 (1982) 521; Haratsch/ Schmahl, ZöR 58 (2003) 108; see also the delegation of Trinidad and Tobago in Vienna, OR 1969 Plenary 35, para. 4: “(wished to state categorically that it did not regard paragraph 5 [of Article 20] as lex lata”).

32YBILC 1966 II 209, para. 1.

33First Award, ILR 54 (1979) 52, para. 61; contra Edwards, Michigan JIL 10 (1989) 398 (“probably not customary law at the time of the Vienna Conference on the Law of Treaties”).

34ICJ Reports 2006, para. 41.

35OR 1968 CoW 111, para. 39; contra Hylton, Vanderbilt JTL 27 (1994) 423 (“[u]nlike

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On the whole, it appears that the Court’s 1951 Reservations to Genocide		7
Advisory Opinion considerably altered traditional views on reservations
(Article 19, N. 2). When Sir Humphrey Waldock and the ILC took up the
topic in 1962, the rules proposed by the Court were most likely innovatory.
However, in view of the large majorities with which States adopted the
various provisions in Vienna in 1968/1969, it appears that Article 19–23
then started crystallising into customary law. It is doubtful whether the
criticism subsequently raised against these articles (N. 2) in fact su ces
to undermine this development since it is directed mainly against matters
not dealt with in the Convention. The Guidelines prepared by the ILC
have rendered these provisions more precise, but have not called Articles
19–23 in question and indeed to not set out to alter them (N. 3), thus in
fact confirming what would appear to be their meanwhile well established
nature also qua customary international law.
E. APPRECIATION
Together with Articles 30 (q.v., N. 24) and 60 (q.v., N. 30), Articles 19–23		8
qualify as the most complex provisions of the Convention. Of central
importance is Article 20 (q.v.). These provisions provide considerable legal
certainty in an area where controversies abound, and they have proved
to be working reasonably well in practice.36 While o ering considerable
flexibility, they aim at providing at least to some extent a balance between
the di erent “schools” on reservations—the main exception being here the
assumption in Article 20, subpara. 4(b), i.e., the so-called “Russian clause”
(q.v., N. 14–15).
Much criticism has been directed against Articles 19–23. It should never-		9
theless be borne in mind that in 1968 and 1969 in Vienna States adopted
the various provisions with considerable, even overwhelming majorities.
States themselves chose these rules. Furthermore, Articles 19–23 do not
amount to jus cogens: States remain free at any time to choose di erent
solutions—either inter se or by stating this in the treaty itself (Article 20,
N. 3)—which may extend, alter, limit or abrogate Articles 19–23.
Not least, finally, the ILC purposely left open who should definitively		10
decide on the incompatibility and hence inadmissibility of a reservation

other parts of the Convention, the articles on reservations were not a codification of international law. Rather the articles were an attempt at progressive development of the law”).

36 Redgwell, BYBIL 64 (1993) 269; Hilpold AVR 43 (1996) 378.

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within the meaning of Article 19, para. (c) (in fact the ILC intended to leave this to States, Article 20, N. 12). Any attempts at resolving this matter di erently today—for instance by proposing an international monitoring body or even judicial settlement—will face the same di culties which confronted the ILC and which led it to propose the rules in today’s Article 19–23 in the first place.

F. APPENDIX—ILC GUIDELINES

11This Appendix reproduces verbatim extracts from the Guidelines prepared by the ILC (N. 3–5). Neither the text nor the numbering are definite, as the ILC’s work is an ongoing project. For reasons of space, the Appendix reproduces only those Guidelines concerning the topic of Articles 19–23, i.e., reservations (and not, for instance, interpretative declarations), and dealing with treaties between States (and not with international organisations).37

RESERVATIONS TO TREATIES

Guide to Practice

1.Definitions

1.1Definition of Reservations

“Reservation” means a unilateral statement, however phrased or named, made by a State . . . when signing, ratifying, formally confirming, accepting, approving or acceding to a treaty or by a State when making a notification of succession to a treaty, whereby the State . . . purports to exclude or to modify the legal e ect of certain provisions of the treaty in their application to that State . . .

1.1.1Object of Reservations

A reservation purports to exclude or modify the legal e ect of certain provisions of a treaty or of the treaty as a whole with respect to certain specific aspects in their application to the State . . . which formulates the reservation.

1.1.2Instances in Which Reservations May Be Formulated

Instances in which a reservation may be formulated under Guideline 1.1 include all the means of expressing consent to be bound by a treaty mentioned in Article 11 of the (Convention) . . .

1.1.3Reservations Having Territorial Scope

A unilateral statement by which a State purports to exclude the application of a treaty or some of its provisions to a territory to which that treaty would be applicable in the absence of such a statement constitutes a reservation.

37T he Guidelines are in YBILC 2007 II/2 46 (with further references to the respective commentaries).

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1.1.4Reservations Formulated When Notifying Territorial Application

A unilateral statement by which a State purports to exclude or to modify the legal e ect of certain provisions of a treaty in relation to a territory in respect of which it makes a notification of the territorial application of the treaty constitutes a reservation.

1.1.5Statements Purporting to Limit The Obligations Of Their Author

A unilateral statement formulated by a State . . . at the time when that State . . . expresses its consent to be bound by a treaty by which its author purports to limit the obligations imposed on it by the treaty constitutes a reservation.

1.1.6Statements Purporting To Discharge An Obligation By Equivalent Means

A unilateral statement formulated by a State . . . when that State . . . expresses its consent to be bound by a treaty by which that State . . . purports to discharge an obligation pursuant to the treaty in a manner di erent from but equivalent to that imposed by the treaty constitutes a reservation.

1.1.7Reservations Formulated Jointly

The joint formulation of a reservation by several States . . . does not a ect the unilateral nature of that reservation.

1.1.8Reservations Made Under Exclusionary Clauses

A unilateral statement made by a State . . . when that State . . . expresses its consent to be bound by a treaty, in accordance with a clause expressly authorising the parties or some of them to exclude or to modify the legal e ect of certain provisions of the treaty in their application to those parties, constitutes a reservation.

1.2Definition of Interpretative Declarations

“Interpretative declaration” means a unilateral statement, however phrased or named, made by a State . . . whereby that State . . . purports to specify or clarify the meaning or scope attributed by the declarant to a treaty or to certain of its provisions.

1.2.1Conditional Interpretative Declarations . . .

1.2.2Interpretative Declarations Formulated Jointly . . .

1.3Distinction Between Reservations and Interpretative Declarations

The character of a unilateral statement as a reservation or an interpretative declaration is determined by the legal e ect it purports to produce.

1.3.1Method of Implementation of the Distinction Between Reservations and Interpretative Declarations

To determine whether a unilateral statement formulated by a State . . . in respect of a treaty is a reservation or an interpretative declaration, it is appropriate to interpret the statement in good faith in accordance with the ordinary meaning to be given to its terms, in light of the treaty to which it refers. Due regard shall be given to the intention of the State . . . concerned at the time the statement was formulated.

1.3.2Phrasing and Name

The phrasing or name given to a unilateral statement provides an indication of the purported legal e ect. This is the case in particular when a State . . . formulates several unilateral statements in respect of a single treaty and designates some of them as reservations and others as interpretative declarations.

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1.3.3 Formulation of a Unilateral Statement When a Reservation is Prohibited

When a treaty prohibits reservations to all or certain of its provisions, a unilateral statement formulated in respect thereof by a State . . . shall be presumed not to constitute a reservation except when it purports to exclude or modify the legal e ect of certain provisions of the treaty or of the treaty as a whole with respect to certain specific aspects in their application to its author.

1.4 Unilateral Statements Other Than Reservations and Interpretative Declarations

Unilateral statements formulated in relation to a treaty which are not reservations nor interpretative declarations are outside the scope of the present Guide to Practice.

1.4.1Statements Purporting to Undertake Unilateral Commitments . . .

1.4.2Unilateral Statements Purporting to Add Further Elements to a Treaty . . .

1.4.3Statements of Non-Recognition . . .

1.4.4General Statements of Policy . . .

1.4.5Statements Concerning Modalities of Implementation of a Treaty at the Internal Level . . .

1.4.6Unilateral Statements Made Under an Optional Clause . . .

1.4.7Unilateral Statements Providing for a Choice Between the Provisions of a Treaty . . .

1.5Unilateral Statements in Respect of Bilateral Treaties . . .

1.5.1“Reservations” To Bilateral Treaties

A unilateral statement, however phrased or named, formulated by a State . . . after initialling or signature but prior to entry into force of a bilateral treaty, by which that State . . . purports to obtain from the other party a modification of the provisions of the treaty to which it is subjecting the expression of its final consent to be bound, does not constitute a reservation within the meaning of the present Guide to Practice.

1.5.2Interpretative Declarations in Respect of Bilateral Treaties …

1.5.3Legal E ect of Acceptance of an Interpretative Declaration Made in Respect of Bilateral Treaty by the Other Party . . .

1.6Scope of Definitions

The definitions of unilateral statements included in the present chapter of the Guide to Practice are without prejudice to the validity and e ects of such statements under the rules applicable to them.

1.7Alternatives to Reservations and Interpretative Declarations

1.7.1Alternatives to Reservations

In order to achieve results comparable to those e ected by reservations, States . . . may also have recourse to alternative procedures, such as:

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–The insertion in the treaty of restrictive clauses purporting to limit its scope or application;

–The conclusion of an agreement, under a specific provision of a treaty, by which two or more States . . . purport to exclude or modify the legal e ects of certain provisions of the treaty as between themselves.

1.7.2Alternatives to Interpretative Declarations . . .

2.Procedure

2.1Form and Notification of Reservations

2.1.1 Written Form

A reservation must be formulated in writing.

2.1.2Form of Formal Confirmation

Formal confirmation of a reservation must be made in writing.

2.1.3Formulation of a Reservation at the International Level

1.(International organisations)

2.By virtue of their functions and without having to produce full powers, the following are considered as representing a State for the purpose of formulating a reservation at the international level:

(a)Heads of State, heads of Government and Ministers for Foreign A airs;

(b)Representatives accredited by States to an international conference for the purpose of formulating a reservation to a treaty adopted at that conference;

(c)(international organisations);

(d)(international organisations).

2.1.4 Absence of Consequences at the International Level of the Violation of Internal Rules Regarding the Formulation of Reservations

The determination of the competent authority and the procedure to be followed at the internal level for formulating a reservation is a matter for the internal law of each State . . .

A State. . . may not invoke the fact that a reservation has been formulated in violation of a provision of the internal law of that State . . . regarding competence and the procedure for formulating reservations as invalidating the reservation.

2.1.5Communication of Reservations

A reservation must be communicated in writing to the contracting States . . . and other States . . . entitled to become parties to the treaty. . . .

2.1.6Procedure for Communication of Reservations

Unless otherwise provided in the treaty or agreed by the contracting States . . . a communication relating to a reservation to a treaty shall be transmitted:

(i) if there is no depositary, directly by the author of the reservation to the contracting States . . . and other States . . . entitled to become parties to the treaty; or

(ii) if there is a depositary, to the latter, which shall notify the States . . . for which it is intended as soon as possible.

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A communication relating to a reservation shall be considered as having been made by the author of the reservation only upon receipt by the State . . . to which it was transmitted, or as the case may be, upon its receipt by the depositary.

The period during which an objection to a reservation may be raised starts at the date on which a State . . . received notification of the reservation.

Where a communication relating to a reservation to a treaty is made by electronic mail or by facsimile, it must be confirmed by diplomatic note or depositary notification. In such a case the communication is considered as having been made at the date of the electronic mail or the facsimile.

2.1.7Functions of Depositaries

The depositary shall examine whether a reservation to a treaty formulated by a State . . . is in due and proper form and, if need be, bring the matter to the attention of the State . . . concerned.

In the event of any di erence appearing between a State . . . and the depositary as to the performance of the latter’s functions, the depositary shall bring the question to the attention of:

(a)the signatory States . . . and the contracting States . . .; or

(b)(international organisations)

2.1.8Procedure in Case of Manifestly Invalid Reservations

Where, in the opinion of the depositary, a reservation is manifestly invalid, the depositary shall draw the attention of the author of the reservation to what, in the depositary’s view, constitutes the grounds for the invalidity of the reservation.

If the author of the reservation maintains the reservation, the depositary shall communicate the text of the reservation to the signatory States and . . . and to the contracting States . . . indicating the nature of legal problems raised by the reservation.

2.2.1Formal Confirmation of Reservations Formulated When Signing a Treaty

If formulated when signing a treaty subject to ratification, act of formal confirmation, acceptance or approval, a reservation must be formally confirmed by the reserving State . . . when expressing its consent to be bound by the treaty. In such a case the reservation shall be considered as having been made on the date of its confirmation.

2.2.2Instances of Non-Requirement of Confirmation of Reservations Formulated When Signing a Treaty

A reservation formulated when signing a treaty does not require subsequent confirmation when a State . . . expresses by its signature the consent to be bound by the treaty.

2.2.3Reservations Formulated Upon Signature When a Treaty Expressly So Provides

A reservation formulated when signing a treaty, where the treaty expressly provides that a State . . . may make such a reservation at that time, does not require formal confirmation by the reserving State . . . when expressing its consent to be bound by the treaty.

2.3.1Late Formulation of a Reservation

Unless the treaty provides otherwise, a State . . . may not formulate a reservation to a treaty after expressing its consent to be bound by the treaty except if none of the other Contracting Parties objects to the late formulation of the reservation.

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2.3.2Acceptance of Late Formulation of a Reservation

Unless the treaty provides otherwise or the well-established practice followed by the depositary di ers, late formulation of a reservation shall be deemed to have been accepted by a Contracting Party if it has made no objections to such formulation after the expiry of the 12-month period following the date on which notification was received.

2.3.3Objection to Late Formulation of a Reservation

If a Contracting Party to a treaty objects to late formulation of a reservation, the treaty shall enter into or remain in force in respect of the reserving State . . . without the reservation being established.

2.3.4 Subsequent Exclusion OR Modification of the Legal E ect of a Treaty by Means Other Than Reservations

A Contracting Party to a treaty may not exclude or modify the legal e ect of provisions of the treaty by:

(a) interpretation of a reservation made earlier; or

(b) a unilateral statement made subsequently under an optional clause.

2.3.5 Widening of the Scope of a Reservation

The modification of an existing reservation for the purpose of widening its scope shall be subject to the rules applicable to the late formulation of a reservation. However, if an objection is made to that modification, the initial reservation remains unchanged.

2.4Procedure for Interpretative Declarations . . .

2.5Withdrawal and Modification of Reservations and Interpretative Declarations

2.5.1 Withdrawal of Reservations

Unless the treaty otherwise provides, a reservation may be withdrawn at any time and the consent of a State . . . which has accepted the reservation is not required for its withdrawal.

2.5.2Form of Withdrawal

The withdrawal of a reservation must be formulated in writing.

2.5.3Periodic Review of the Usefulness Of Reservations

States . . . which have made one or more reservations to a treaty should undertake a periodic review of such reservations and consider withdrawing those which no longer serve their purpose.

In such a review, States . . . should devote special attention to the aim of preserving the integrity of multilateral treaties and, where relevant, give consideration to the usefulness of retaining the reservations, in particular in relation to developments in their internal law since the reservations were formulated.

2.5.4Formulation of the Withdrawal of a Reservation at the International Level

1.[A] person is competent to withdraw a reservation made on behalf of a State . . . if:

(a)that person produces appropriate full powers for the purposes of that withdrawal; or

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(b)it appears from practice or other circumstances that it was the intention of the States . . . concerned to consider that person as competent for such purposes without having to produce full powers.

2.By virtue of their functions and without having to produce full powers, the following are competent to withdraw a reservation at the international level on behalf of a State:

(a)heads of State, heads of Government and Ministers for Foreign A airs;

(b)(international organisations);

(c)(international organisations).

2.5.5 Absence of Consequences at the International Level of the Violation of Internal Rules Regarding the Withdrawal of Reservations

The determination of the competent body and the procedure to be followed for withdrawing a reservation at the internal level is a matter for the internal law of each State . . .

A State . . . may not invoke the fact that a reservation has been withdrawn in violation of a provision of the internal law of that State . . . regarding competence and the procedure for the withdrawal of reservations as invalidating the withdrawal.

2.5.6Communication of Withdrawal of a Reservation

The procedure for communicating the withdrawal of a reservation follows the rules applicable to the communication of reservations contained in Guidelines 2.1.5, 2.1.6 and 2.1.7.

2.5.7E ect of Withdrawal of a Reservation

The withdrawal of a reservation entails the application as a whole of the provisions on which the reservation had been made in the relations between the State . . . which withdraws the reservation and all the other parties, whether they had accepted the reservation or objected to it.

The withdrawal of a reservation entails the entry into force of the treaty in the relations between the State . . . which withdraws the reservation and a State . . . which had objected to the reservation and opposed the entry into force of the treaty between itself and the reserving State . . . by reason of that reservation.

2.5.8E ective Date of Withdrawal of a Reservation

Unless the treaty otherwise provides, or it is otherwise agreed, the withdrawal of a reservation becomes operative in relation to a contracting State . . . only when notice of it has been received by that State . . .

Model Clauses

A. Deferment of the E ective Date of the Withdrawal of a Reservation

A Contracting Party which has made a reservation to this treaty may withdraw it by means of notification addressed to [the depositary]. The withdrawal shall take e ect on the expiration of a period of X [months] [days] after the date of receipt of the notification by [the depositary].

B. Earlier E ective Date of Withdrawal of a Reservation

A Contracting Party which has made a reservation to this treaty may withdraw it by means of a notification addressed to [the depositary]. The withdrawal shall take e ect on the date of receipt of such notification by [the depositary].

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C. Freedom to Set the E ective Date of Withdrawal of a Reservation

A Contracting Party which has made a reservation to this treaty may withdraw it by means of a notification addressed to (the depositary). The withdrawal shall take e ect on the date set by that State in the notification addressed to (the depositary).

2.5.9 Cases in Which a Reserving State . . . may Unilaterally Set the E ective Date of Withdrawal of a Reservation

The withdrawal of a reservation takes effect on the date set by the withdrawing State . . . where:

(a)That date is later than the date on which the other contracting States . . . received notification of it; or

(b)The withdrawal does not add to the rights of the withdrawing State . . ., in relation to the other contracting States . . .

2.5.10Partial Withdrawal of a Reservation

The partial withdrawal of a reservation limits the legal e ect of the reservation and achieves a more complete application of the provisions of the treaty, or of the treaty as a whole, to the withdrawing State . . .

The partial withdrawal of a reservation is subject to the same formal and procedural rules as a total withdrawal and takes e ect on the same conditions.

2.5.11E ect of a Partial Withdrawal of a Reservation

The partial withdrawal of a reservation modifies the legal e ect of the reservation to the extent of the new formulation of the reservation. Any objection made to the reservation continues to have e ect as long as its author does not withdraw it, insofar as the objection does not apply exclusively to that part of the reservation which has been withdrawn.

No objection may be made to the reservation resulting from the partial withdrawal, unless that partial withdrawal has a discriminatory e ect.

2.5.12 Withdrawal of an Interpretative Declaration . . .

An interpretative declaration may be withdrawn at any time by the authorities competent for that purpose, following the same procedure applicable to its formulation.

2.5.13 Withdrawal of a Conditional Interpretative Declaration . . .

2.6.1Definition of Objections to Reservations

“Objection” means a unilateral statement, however phrased or named, made by a State . . . in response to a reservation to a treaty formulated by another State . . ., whereby the former State . . . purports to exclude or to modify the legal e ects of the reservation, or to exclude the application of the treaty as a whole, in relations with the reserving State . . .

2.6.2 Definition of objections to the Late Formulation or Widening of the Scope of a Reservation

“Objection” may also mean a unilateral statement whereby a State . . . opposes the late formulation of a reservation or the widening of the scope of a reservation.

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3. Validity of Reservations and Interpretative Declarations

3.1Permissible Reservations

A State . . . may, when signing, ratifying, formally confirming, accepting, approving or acceding to a treaty, formulate a reservation unless:

(a)the reservation is prohibited by the treaty;

(b)the treaty provides that only specified reservations, which do not include the reservation in question, may be made; or

(c)in cases not falling under subparagraphs (a) and (b), the reservation is incompatible with the object and purpose of the treaty.

3.1.1Reservations Expressly Prohibited by the Treaty

A reservation is expressly prohibited by the treaty if it contains a particular provision:

(a)prohibiting all reservations;

(b)prohibiting reservations to specified provisions and a reservation in question is formulated to one of such provisions; or

(c)prohibiting certain categories of reservations and a reservation in question falls within one of such categories.

3.1.2Definition of Specified Reservations

For the purposes of Guideline 3.1, the expression “specified reservations” means reservations that are expressly envisaged in the treaty to certain provisions of the treaty or to the treaty as a whole with respect to certain specific aspects.

3.1.3Permissibility of Reservations not Prohibited by the Treaty

Where the treaty prohibits the formulation of certain reservations, a reservation which is not prohibited by the treaty may be formulated by a State . . . only if it is not incompatible with the object and purpose of the treaty.

3.1.4Permissibility of Specified Reservations

Where the treaty envisages the formulation of specified reservations without defining their content, a reservation may be formulated by a State . . . only if it is not incompatible with the object and purpose of the treaty.

3.1.5Incompatibility of a Reservation with the Object and Purpose of the Treaty

A reservation is incompatible with the object and purpose of the treaty if it a ects an essential element of the treaty that is necessary to its general thrust, in such a way that the reservation impairs the raison d’être of the treaty.

3.1.6Determination of the Object and Purpose of the Treaty

The object and purpose of the treaty is to be determined in good faith, taking account of the terms of the treaty in their context. Recourse may also be had in particular to the title of the treaty, the preparatory work of the treaty and the circumstances of its conclusion and, where appropriate, the subsequent practice agreed upon by the parties.

3.1.7 Vague or General Reservations

A reservation shall be worded in such a way as to allow its scope to be determined, in order to assess in particular its compatibility with the object and purpose of the treaty

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3.1.8Reservations to a Provision Reflecting a Customary Norm

1.The fact that a treaty provision reflects a customary norm is a pertinent factor in assessing the validity of a reservation although it does not in itself constitute an obstacle to the formulation of the reservation to that provision.

2.A reservation to a treaty provision which reflects a customary norm does not a ect the binding nature of that customary norm which shall continue to apply as such between the reserving State . . . and other States . . . which are bound by that norm.

3.1.9Reservations Contrary to a Rule of jus cogens

A reservation cannot exclude or modify the legal e ect of a treaty in a manner contrary to a peremptory norm of general international law.

3.1.10Reservations to Provisions Relating to Non-Derogable Rights

A State . . . may not formulate a reservation to a treaty provision relating to non-derogable rights unless the reservation in question is compatible with the essential rights and obligations arising out of that treaty. In assessing that compatibility, account shall be taken of the importance which the parties have conferred upon the rights at issue by making them non-derogable.

3.1.11Reservations Relating to Internal Law

A reservation by which a State . . . purports to exclude or to modify the legal e ect of certain provisions of a treaty or of the treaty as a whole in order to preserve the integrity of specific norms of the internal law of that State . . . may be formulated only insofar as it is compatible with the object and purpose of the treaty.

3.1.12Reservations to General Human Rights Treaties

To assess the compatibility of a reservation with the object and purpose of a general treaty for the protection of human rights, account shall be taken of the indivisibility, interdependence and interrelatedness of the rights set out in the treaty as well as the importance that the right or provision which is the subject of the reservation has within the general thrust of the treaty, and the gravity of the impact the reservation has upon it.

3.1.13 Reservations to Treaty Provisions Concerning Dispute Settlement or the Monitoring of the Implementation of the Treaty

A reservation to a treaty provision concerning dispute settlement or the monitoring of the implementation of the treaty is not, in itself, incompatible with the object and purpose of the treaty, unless:

(i) the reservation purports to exclude or modify the legal e ect of a provision of the treaty essential to its raison d’être; or

(ii) the reservation has the e ect of excluding the reserving State . . . from a dispute settlement or treaty implementation monitoring mechanism with respect of a treaty provision that it has previously accepted, if the very purpose of the treaty is to put such a mechanism into e ect.

Section . Entry into Force and Provisional Application of Treaties

Article 24

Entry into force

1.A treaty enters into force in such manner and upon such date as it may provide or as the negotiating States may agree.

2.Failing any such provision or agreement, a treaty enters into force as soon as consent to be bound by the treaty has been established for all the negotiating States.

3.When the consent of a State to be bound by a treaty is established on a date after the treaty has come into force, the treaty enters into force for that State on that date, unless the treaty otherwise provides.

4.The provisions of a treaty regulating the authentication of its text, the establishment of the consent of States to be bound by the treaty, the manner or date of its entry into force, reservations, the functions of the depositary and other matters arising necessarily before the entry into force of the treaty apply from the time of the adoption of its text.

Article 24 Entrée en vigueur

1.Un traité entre en vigueur suivant les modalités et à la date fixées par ses dispositions ou par accord entre les Etats ayant participé à la négociation.

2.A défaut de telles dispositions ou d’un tel accord, un traité entre en vigueur dès que le consentement à être lié par le traité a été établi pour tous les Etats ayant participé à la négociation.

3.Lorsque le consentement d’un Etat à être lié par un traité est établi à une date postérieure à l’entrée en vigueur dudit traité, celui-ci, à moins qu’il n’en dispose autrement, entre en vigueur à l’égard de cet Etat à cette date.

4.Les dispositions d’un traité qui réglementent l’authentification du texte, l’établissement du consentement des Etats à être liés par le traité, les modalités ou la date d’entrée en vigueur, les réserves, les fonctions du dépositaire, ainsi que les autres questions qui se posent nécessairement avant l’entrée en vigueur du traité, sont applicables dès l’adoption du texte.

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Artikel 24 Inkrafttreten

1.Ein Vertrag tritt in der Weise und zu dem Zeitpunkt in Kraft, die er vorsieht oder die von den Verhandlungsstaaten vereinbart werden.

2.In Ermangelung einer solchen Bestimmung oder Vereinbarung tritt ein Vertrag in Kraft, sobald die Zustimmung aller Verhandlungsstaaten vorliegt, durch den Vertrag gebunden zu sein.

3.Wird die Zustimmung, durch einen Vertrag gebunden zu sein, von einem Staat erst nach dem Zeitpunkt des Inkrafttretens erteilt, so tritt der Vertrag für diesen Staat zu diesem Zeitpunkt in Kraft, sofern er nichts anderes vorsieht.

4.Vertragsbestimmungen über die Festlegung des authentischen Textes, die Zustimmung von Staaten, durch den Vertrag gebunden zu sein, die Art und den Zeitpunkt seines Inkrafttretens sowie über Vorbehalte, die Aufgaben des Verwahrers und sonstige sich notwendigerweise vor dem Inkrafttreten des Vertrags ergebende Fragen gelten von dem Zeitpunkt an, zu dem sein Text angenommen wird.

ILC Draft 1966

Article 21—Entry into force

Unless the treaty otherwise provides, instruments of ratification, acceptance, approval or accession establish the consent of a State to be bound by a treaty upon:

1.A treaty enters into force in such manner and upon such date as it may provide or as the negotiating States may agree.

2.Failing any such provision or agreement, a treaty enters into force as soon as consent to be bound by the treaty has been established for all the negotiating States.

3.When the consent of a State to be bound is established after a treaty has come into force, the treaty enters into force for that State on the date when its consent was established unless the treaty otherwise provides.

Materials:

Waldock Report I: Articles 20 and 21.

Minutes: YBILC 1962 I 175 f, 179 f, 258, 286, 291.

ILC Draft 1962: Article 23.

Waldock Report IV: Article 23.

Minutes: YBILC 1965 99 , 273 f, 285.

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ILC Draft 1965: Article 23.

Minutes: YBILC 1966 I/2 273 f, 293, 327, 340 f.

ILC Draft 1966: Article 23.

Minutes: OR 1968 CoW 138 , 426; OR 1969 Plenary 39.

Vienna Conference Vote: 99:0:0

Selected Literature:

K. Lewan, Which States Must be Bound Before a Multilateral Treaty Enters into Force if Nothing is Specified? ZaöRV 29 (1969) 536 ; A. Mahiou, Article 24, in: Corten/Klein (eds.) 1023 ; P. Reuter, The Operational and Normative Aspects of Treaties, Israel LR 20 (1985) 123 ; E. Roucounas, Uncertainties Regarding the Entry into Force of Some Multilateral Treaties, in: K. Wellens (ed.), International Law: Theory and Practice. Essays in Honour of E. Suy (1998) 179 ; H.D. Treviranus, Neue Verfahren zur Vereinfachung und Beschleunigung des Zustandekommens von multilateralen Verträgen, Friedens-Warte 59 (1976) 51 .

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	CONTENTS
		Paras.
A. Background ........................................................................................		1
1.	Introduction .....................................................................................	1
2.	History .............................................................................................	1
B. Interpretation of Article 24 ............................................................		3
1.	Scope ...............................................................................................	3
2.	Principal Rule: Parties’ Intention (Para. 1) .......................................	6
3.	Residuary Rule (Para. 2) ...................................................................	8
4.	Subsequent Establishment of Consent to be Bound (Para. 3) ...........	11
5.	Application before Entry into Force (Para. 4) ...................................	12
C. Context ...............................................................................................		14
1.	Relationship to Other Provisions ......................................................	14
2.	Customary Basis of Article 24 ...........................................................	15
D. Appreciation .......................................................................................		16

A. BACKGROUND

1.Introduction

1 Traditionally, general international law envisaged only a few rules on a treaty’s entry into force. As the 1935 Harvard Draft explained, unless the treaty provided otherwise, it entered into force upon the exchange or deposit of all ratifications or, if it was not subject to ratification, upon signature.1

2.History

2Fitzmaurice Report I of 1956 mentioned various rules on the treaty’s entry into force and contained, inter alia, the presumption that when a final date for signature or ratification was laid down in a treaty, the intention was that it should enter into force on that date for the States which by then had signed or ratified it.2 Based thereupon, Waldock Report I and the ILC Draft 1962

1 AJIL 29 (1935) Supplement 787 (Article 10).

2YBILC 1956 II 116 (Articles 41 and 42). There was also a presumption that where a treaty was silent, the parties’ intention was that signature or ratification by all the participants would be required to bring it into force (i.e., the rule in para. 2, N. 6–7). See on this Jiménez de Aréchaga in the ILC, YBILC 1965 I 104, para. 47.

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envisaged a similar solution; moreover, if the treaty failed to specify the time of its entry into force, it was assumed that any date fixed for ratification, acceptance etc. would become the date of entry into force.3 Even though Governments did not object thereto,4 the ILC in 1965 and 1966 decided to omit these presumptions and to prepare a solution along the lines of the final Article 24.5 The ILC Draft 1966 underwent only minor changes in Vienna, though the Conference decided to add para. 4 (N. 12–13).6 In 1969 Article 24 was adopted by 99 votes to none.7

B. INTERPRETATION OF ARTICLE 24
1. Scope
Various stages lead up to the treaty’s entry into force.	3
After a treaty text has been adopted (Article 9, q.v.) and authenticated (Article 10, q.v.),
States have various means to express their consent to be bound by the treaty (Articles
11–15, q.v.). Once they have expressed their consent and pending the treaty’s entry
into force, they are under an obligation not to defeat the object and purpose of the
treaty prior to its entry into force (Article 18, q.v.); also, the treaty or the parties may
envisage the provisional application of the treaty (Article 25, q.v.). Once consent to be
bound has been established according to Article 16 (q.v.), the treaty enters into force
and is binding for States parties.
With the treaty’s entry into force, States are obliged to apply the treaty.8	4
The entry into force may occur at the same time as the establishment of the

3Articles 20 and 21 of Waldock Report I, YBILC 1962 II 68 ; Article 23 of the ILC Draft 1962, ibid. 182; see also ILC Report 1966, YBILC 1966 II 209 f, para. 1. In 1962 the ILC

found the provisions generally somewhat complex; see YBILC 1962 I 175 f, and 179 f.

4T heir observations are reproduced in Waldock Report IV, YBILC 1965 II 56 ; see the statement by Waldock in the ILC, YBILC 1965 I 99, para. 60. Article 23 of the ILC Draft

1965 is at YBILC 1965 II 162.

5See the new versions presented at YBILC 1965 I 273, para. 31, and 285, para. 72 (adopted by 17 votes to none). Article 23 of the ILC Draft 1965 is at YBILC 1965 II 162. This omission was considered “a small point of substance”; see Waldock in the ILC, YBILC 1965 I 274, para. 32. See also the explanations in the ILC Report 1966, YBILC 1966 II

209 f, para. 1.

6T he ILC Report 1966 is at ibid. 209 f. The amendments are reproduced in OR Documents 142, paras. 213 f. Para. 4 goes back to an amendment by the UK delegation, ibid. subpara. 214(iv). See here also Sinclair, Vienna Convention 45 f. Para. 3 underwent certain textual changes, e.g., “on that date” instead of “on the date when its consent was established”.

7 OR 1969 Plenary 39, para. 51.

8Article 24 was referred to by the ICJ in the Land and Maritime Boundary (Cameroon/Nigeria) Case, ICJ Reports 1998 293 f, para. 31.

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consent to be bound according to Article 15 or at a later stage, depending on what is provided in the treaty and, subsidiarily, on Article 24.9

5The treaty’s entry into force and application does not necessarily imply its immediate operation; it may be executed at a later date.10

For instance, a treaty of commerce entering into force on 1 January, may become operational only later in the year when the obligation of delivery arises.11

2. Principal Rule: Parties’ Intention (Para. 1)

6Para. 1 provides the basic rule according to which a treaty enters into force in such manner and upon such date as it may provide or as the negotiating States may agree. A priori, the parties’ intention must be established either within or outside the treaty, i.e., in additional instruments, expressed informally, or even in subsequent practice.12 The negotiating States are those which took part in the drawing up and adoption of the text of the treaty (Article 2, subpara. 1[e], q.v., N. 40–42). If no such intention transpires as regards the manner and the date of the entry into force, paras. 2–4 will apply (N. 8–13).

If in a treaty a date is fixed for the exchange or deposit of instruments or for signature and this amounts to a clear indication as to the treaty’s entry into force, this situation falls under para. 1 (N. 2).13

9See Article 21, subparas. 1(a) and (b) of Waldock Report I, YBILC 1962 II 71; previously already Article 42, para. 2 of Fitzmaurice Report I, YBILC 1956 II 116.

10Waldock in the ILC, YBILC 1965 I 105, para. 64 (“di erence between the entry into force of a treaty for a party and the date . . . from which the obligations imposed by the treaty began to operate”); Blix/Emerson 75 (“ ‘becoming binding’ designates the moment when consent becomes irrevocable and . . . ‘becoming operative’ designates the moment when obligations under a treaty are to be performed”); Verdross/Simma 459 at n. 37.

11Harvard Draft, AJIL 29 (1935) Supplement 787; the statement by Briggs in the ILC, YBILC 1965 I 105, para. 66 (“the 1949 Geneva Convention for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field . . . which presumably did not become operative until war broke out”).

12See the ILC Report 1966, YBILC 1966 II 210, para. 2; the statements by Castren in the ILC, YBILC 1965 I 101, para. 7 (“the first thing to do was . . . to consult the provisions of the treaty itself concerning its entry into force”); and Lachs, ibid. 102, para. 31 (“sometimes States failed to fix a date for the entry into force of a treaty and additional instruments had to be signed laying down conditions for entry into force”). Article 29, para. 7 of Waldock Report I, YBILC 1962 II 69, envisaged the possibility of “provisions of a treaty being brought into force by . . . subsequent acts of the States concerned”.

13ILC Report 1966, ibid.; Sinclair, Vienna Convention 44.

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Aust has listed various ways in which express provisions may provide for a		7
treaty’s entry into force:14

–upon a date specified in the treaty;

–upon signature only by all the negotiating States;

–upon ratification by both or all signatory States;

–upon the signature or ratification of certain States specified in the treaty;

–upon signature or ratification by a minimum number of States (see, e.g., Article 84, para. 1, q.v., N. 1);

–upon the exchange of instruments of ratification in the case of a bilateral treaty;

–upon notification by each signatory State to the other of the completion of its constitutional requirements;

–in the case of a treaty constituted by an exchange of notes: upon the date of the reply note;

–upon a date yet to be agreed.

3.Residuary Rule (Para. 2)

If no such intention can be established (N. 6), i.e., failing any such provision			8
or agreement within or outside the treaty,15 para. 2 provides for the practical
solution (rather than a presumption, N. 2)16 that the treaty enters into force
as soon as consent to be bound by the treaty has been established for all
the negotiating States. The treaty must bind at least two States.17
	If the treaty provides for the date when the ratifications have to take place (N. 6),
	though the last ratification occurs earlier, a conflict arises between paras. 1 and 2 of
	Article 24. Here, it can be assumed that the parties did not express their intention on
	this particular situation as in para. 1, and the treaty enters into force upon the earlier
	date according to para. 2.18
All negotiating States have to consent to be bound by the treaty, i.e., all			9
States involved in its adoption (Article 9, q.v.), in particular at a conference,
whether voting for or against the text.19 This condition may be useful and is
14	Modern Treaty Law 163 .
15	T he link between paras. 1 and 2 is reinforced by the use of the same words “provide
	or . . . agree” in para 1 and “provision or agreement” in para. 2.

16But see ILC Report 1966, YBILC 1966 II 210, para. 3 (“general presumption”).

17Article 41, para. 1 of Fitzmaurice Report I, YBILC 1956 II 116.

18See the statement by Ago in the ILC, YBILC 1965 I 100, para. 73.

19See the statement in Vienna by Virally of the French delegation, OR 1968 CoW 139, para. 12 (“silence should be construed as meaning that acceptance by all the negotiating States was necessary. If any other rule was applied, it should be stated expressly in the treaty”); ILC Report 1966, YBILC 1966 II 210, para. 3; the statement by Lachs in the ILC, YBILC 1965 I 102, para. 29 (“a strong presumption that . . . only ratification,

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indeed usual in the case of restricted multilateral treaties. However, it may prove a formidable obstacle in the case of a general multilateral treaty where it can hardly be expected that States having voted against the adoption of the treaty at a conference will subsequently consent to be bound by it.20

Choosing a lower threshold, e.g., a two-thirds majority, appears di cult and even artificial and runs counter to the general rule which is that of the unanimity of States required for the treaty’s entry into force.21 Indeed, such a threshold was expressly rejected by States in Vienna.22 In practice, particularly at conferences preparing general multilateral treaties, a minimum number of States required for the treaty’s entry into force is usually mentioned in the treaty (Article 84, para. 1, q.v., N. 1).

10Para. 2 does not (and need not) mention a particular date when the treaty enters into force, since this will occur when consent to be bound by the treaty has been established by all negotiating States, and in particular by the last negotiating State. If all States establish consent to be bound on the same day and the treaty is otherwise silent on matters of entry into force, Article 24 coincides with Article 15 (N. 4).

Multilateral treaties usually provide that the date of entry into force occurs on a specified number of days or months following the deposit of the last instrument of ratification (Article 84, para. 1, q.v., N. 2).23

4. Subsequent Establishment of Consent to be Bound (Para. 3)

11Para. 3 concerns the case where the consent of a State to be bound by a treaty is established on a date after the treaty has come into force. The undisputed rule here—an aspect of the non-retroactivity of treaties (Article 28, q.v.)24—is that the treaty enters into force for that State on that date, i.e., for each new party on the date when its consent to be bound is established.25 This is subject to para. 1 (N. 5–6), though it is also stated in para. 3 ex abundanti cautela that the treaty may otherwise provide.

acceptance or approval by all the participants could bring the treaty into force. That point was of crucial importance”).

20Do Nascimento e Silva, RC 154 (1977 I) 227; Lewan, ZaöRV 29 (1969) 537 (“ridiculous result”).

21Statement by Yasseen in the ILC, YBILC 1965 I 103, para. 37.

22At the Vienna Conference, the Chilean delegation proposed in para. 2 the word “twothirds” instead of “all”, OR Documents 142, paras. 213 f; see the statement by the Chilean delegation, OR 1968 CoW 139, para. 4 (“what would become of a treaty negotiated or even signed by several States which was not ratified by all those States . . . the treaty would not be able to enter into force”); the amendment was rejected by 64 votes to 9, with 15 abstentions, ibid. 140, para. 21. See also Article 41, para. 3 of Fitzmaurice Report I, YBILC 1956 11 116.

23Aust, Modern Treaty Law 168 f; ILC Report 1966, YBILC 1966 II 210, para. 5.

24Do Nascimento e Silva, RC 154 (1977 I) 228.

25ILC Report 1966, YBILC 1966 II 210, para. 4. Amado criticised in the ILC the apparent

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If a period is provided in the treaty after which it enters into force once consent to be bound has been established by all States (N. 10), then this period is usually also envisaged in the case of further States giving their consent after the treaty’s entry into force.

5. Application before Entry into Force (Para. 4)

In principle, the rules of a treaty become applicable solely after its entry into 12 force (Article 28, q.v.).26 Para. 4, introduced at the Vienna Conference in 1968 (N. 2), explains how to deal with certain procedural issues early on

in a treaty’s life, inter alia, its final clauses,27 arising necessarily before the entry into force of the treaty. Put bluntly, how can provisions on the treaty’s entry into force be applied before its entry into force? Para. 4 states that the provisions of a treaty regulating these procedural issues apply from the time of the adoption of its text.28 This is a kind of immediate e ect of a treaty.29 Para. 4 lists the following such procedural issues:

–the authentication of its text (Article 10, q.v.);

–the establishment of the consent of States to be bound by the treaty (Articles 11–15, q.v);

–the manner or date of its entry into force (Article 24, paras. 1–3, N. 5–10), as for instance in Articles 81–84 (q.v.);

–reservations (Articles 19–23, q.v.);

–the functions of the depositary (Articles 76–77, q.v.); and

–and other matters; para. 4 thereby confirms that the list is not exclusive.

Sinclair has argued that the “word ‘necessarily’ [in para. 4] . . . may not be entirely apposite. Certain of the listed matters, such as those concerning . . . reservations . . . may apply both before and after entry into force”.30 However, it does not seem possible for a State to make a reservation after the treaty has entered into force in respect of this State (Article 19, para. 1, N. 9). Thus, para. 4 must be read together with para. 3.

It is doubtful whether para. 4 truly concerns a retroactive application of the 13 treaty’s provisions. Rather, the source of the legal validity can be seen, on the

one hand, in the early consent given by the negotiating States when adopting the text of the treaty.31 On the other, it can be argued that the legal validity

tautology in para. 3, YBILC 1965 I 103, para. 42 (“what was the use of saying that a State was bound when it was bound”).

26But see Articles 18 and 25.

27Verdross/Simma, N. 461, refer here to the “service du traité”.

28I.e., the adoption of the entire text rather than voting on individual provisions during the conference; see Article 9, N. 3.

29Reuter, Introduction p. 68.

30Vienna Convention 46.

31See the statements in Vienna by the Expert Consultant, Sir Humphrey Waldock, OR

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lies in the binding force of Article 24, para. 4 both qua contractual obligation of the Convention and (even more importantly in view of the general application of the Convention:) qua customary law of Article 24 (N. 15).32

C.CONTEXT

1.Relationship to Other Provisions

14Article 24 flows from pacta sunt servanda (Article 26, q.v.).33 As has been pointed out above (N. 3–12), Article 24 is closely linked with various other articles of the Convention.

2. Customary Basis of Article 24

15The International Court of Justice has referred to Article 24 as a “general” rule which is, hence, declaratory of customary international law.34

D. APPRECIATION

16Article 24 appears relevant and of considerable practical use despite an apparent element of tautology35 and even if much is left for regulation in the treaty itself. In fact, there is more in the provision than immediately meets the eye. The residuary rules in paras. 2–4 provide welcome solutions where early disagreement between the parties may arise after the adoption of the treaty.36

1968 CoW 140, para. 16; by Sinclair of the UK delegation, OR 1968 CoW 139, para. 5; also Reuter, Israel LR 20 (1985) 126 (“collective consent given at the time of adoption of the text—a sort of provisional agreement on the text”); and the Harvard Draft, AJIL 29 (1935) Supplement 787.

32See the statement in Vienna by Yasseen of the Iraqi delegation, OR 1968 CoW 140, para. 17.

33ILC Report 1966, YBILC 1966 II 211, para. 3.

34Land and Maritime Boundary (Cameroon/Nigeria) Case, ICJ Reports 1998 294, para. 31; see the diss. op. of Judge Kreca in the Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia-Herzegovina v. Yugoslavia) Case (Preliminary Objections), ICJ Reports 1996 794, para. 120 (“the rule of general international law, expressed in paragraph 3 of Article 24”). See also the observation by the US Government on the ILC Draft 1962, Waldock Report IV, YBILC 1965 II 57 (“[reflecting] present-day practices”); the statement in Vienna by Yasseen of the Iraqi delegation, OR 1968 CoW 140, para. 17 (“[para. 4] was the expression of an existing rule of international law”).

35See the statement by Amado in the ILC, YBILC 1965 I 103, para. 42 (cited in n. 25).

36Jiménez de Aréchaga in the ILC, ibid., paras. 45–46; Briggs, ibid. 101, para. 19 (“important . . . and ought to be retained”).

Article 25

Provisional application

1.A treaty or a part of a treaty is applied provisionally pending its entry into force if:

(a)the treaty itself so provides; or

(b)the negotiating States have in some other manner so agreed.

2.Unless the treaty otherwise provides or the negotiating States have otherwise agreed, the provisional application of a treaty or a part of a treaty with respect to a State shall be terminated if that State notifies the other States between which the treaty is being applied provisionally of its intention not to become a party to the treaty.

Article 25 Application à titre provisoire

1.Un traité ou une partie d’un traité s’applique à titre provisoire en attendant son entrée en vigueur:

a)si le traité lui même en dispose ainsi; ou

b)si les États ayant participé à la négociation en étaient ainsi convenus d’une autre manière.

2.A moins que le traité n’en dispose autrement ou que les États ayant participé à la négociation n’en soient convenus autrement, l’application à titre provisoire d’un traité ou d’une partie d’un traité à l’égard d’un État prend fin si cet État notifie aux autres États entre lesquels le traité est appliqué provisoirement, son intention de ne pas devenir partie au traité.

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Artikel 25 Vorläufige Anwendung

1.Ein Vertrag oder ein Teil eines Vertrages wird bis zu seinem Inkrafttreten vorläufig angewendet, wenn:

a)der Vertrag selbst es so vorsieht; oder

b)die verhandelnden Staaten dies in anderer Weise vereinbart haben.

2.Falls der Vertrag nichts anderes vorsieht oder die verhandelnden Staaten nichts anderes vereinbart haben, endet die vorläufi ge Anwendung eines Vertrages oder eines Teiles eines Vertrages für einen Staat, wenn dieser Staat den anderen Staaten, zwischen denen der Vertrag vorläufig angewendet wird, seine Absicht notifiziert, kein Vertragspartner zu werden.

ILC Draft 1966

Article 22—Entry into force provisionally

1.A treaty may enter into force provisionally if:

(a)The treaty itself prescribes that it shall enter into force provisionally pending ratification, acceptance, approval or accession by the contracting States; or

(b)The negotiating States have in some other manner so agreed.

2.The same rule applies to the entry into force provisionally of part of a treaty.

Materials:

WALDOCK Report I: Article 20, para. 7, Article 21 para. 2. Minutes: YBILC 1962 I 179 , 212, 259, 291.

ILC Draft 1962: Article 24.

WALDOCK Report IV: Article 24.

Minutes: YBILC 1965 I 105 , 274 f, 285.

ILC Draft 1965: Article 24.

ILC Draft 1966: Article 22.

Minutes: OR 1968 CoW 140 , 426 f; OR 1969 Plenary 39 , 157 f.

Vienna Conference Vote: 87:1:13

Selected Literature:

A. Geslin, La mise en application provisoire des traités (2005); R. Lefeber, The Provisional Application of Treaties, in: J. Klabbers/R. Lefeber (eds.), Essays on the Law of Treaties. A

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Collection of Essays in Honour of B. Vierdag (1998) 81 ; D. Mathy, Article 25, in: Corten/Klein (eds.) 1047 ; A. Michie, The Provisional Application of Arms Control Treaties, Journal CSL 10 (2005) 345 ; M.A. Rogoff/B.E. Gauditz, The Provisional Application of International Agreements, Maine LR 39 (1987) 29 ; G.E. do Nascimento e Silva, Le facteur temps et les traités, RC 154 (1977 I) 221 ; E. Orihuela Calatayud, Los tratados internacionales y su aplicacion en el tiempo: Consideraciones sobre el efecto inicial de las disposiciones convencionales (2004); V. Picone, L’applicazione in via provvisoria degli accordi internazionali (1973); Th. Sägesser, Die vorläufige Anwendung völkerrechtlicher Verträge durch den Schweizerischen Bundesrat, recht 21 (2003) 85 ; D. Vignes, Une notion ambiguë: La mise en application provisoire des traités, AFDI 18 (1972) 181 .

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	CONTENTS
		Paras.
A. Background ........................................................................................		1
1.	Introduction .....................................................................................	1
2.	History ............................................................................................	2
B. Interpretation of Article 25 ............................................................		4
1.	Concept of Provisional Application ..................................................	4
2.	Conditions of Provisional Application (Para. 1) ................................	7
3.	Termination (Para. 2) .......................................................................	8
C. Reservations .......................................................................................		10
D. Context ...............................................................................................		11
1.	Relationship to Other Provisions ......................................................	11
2.	Customary Basis of Article 25 ...........................................................	12
E. Appreciation .......................................................................................		13

A. BACKGROUND

1. Introduction

1 It is common practice in international relations for negotiating States to declare the forthcoming treaty, or certain provisions contained therein, provisionally applicable pending the entry into force of the treaty. Such treaties may relate to political issues, such as Article 3 of the early 1934 Pacte d’entente balkanique providing an end to hostilities.1 More often, they concern “technical” matters such as trade, transport, judicial assistance and social security. Article 68 of the Agreement on an International Energy Program of 1974 provided for its provisional application as a reaction to the oil crisis of 1973/1974, and Article 13 of the IAEA Convention on the Early Notification of a Nuclear Incident of 1986 was a response to the Chernobyl nuclear power plant incident in the same year.2 States may choose this manner of proceeding for di erent reasons, i.e., (i) in view of the urgency of the treaty and the length of parliamentary approbation procedures; (ii) when its content appears highly desirable and subsequent ratification is not doubtful; or (iii) when the States parties wish to prepare the way for the entry into force of the entire treaty.3

1 See Lefeber, Provisional Application 82; the examples in Vignes, AFDI 18 (1972) 182 ; also H.-G. Krenzler, Die vorläufige Anwendung völkerrechtlicher Verträge (1963).

2 ILM 14 (1975) 1, 25 (1986) 1370; see also Lefeber, ibid. 83.

3See the statement by the Expert Consultant in Vienna, Sir Humphrey Waldock, OR 1969 Plenary 43, para. 89; the ILC Report 1966, YBILC 1966 II 210, para. 2.

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2. History
Already the Fitzmaurice Report I in 1956 contained the core of the present		2
Article 28.4 Waldock Report I of 1962 referred to provisional application
in Articles 20 (Mode and Date of Entry into Force) and 21 (Legal E ects of
Entry into Force).5 The ILC Report 1962 consolidated these principles in a
single Article 24 concerning the Provisional Entry into Force.6 After further
lengthy discussions in 1965, the ILC adopted its 1966 Draft containing the
substance of the present para. 1 of Article 28.7
The ILC Draft 1966 faced some resistance at the 1968/1969 Vienna Confer-		3
ence. A move by certain States to delete the provision altogether found no
agreement and was not pressed.8 On the other hand, the ILC draft proposal
underwent considerable changes. Its para. 2, distinguishing between the

provisional application of the whole treaty or only parts of it, was included in the present para. 1.9 The terms “provisional entry into force”, appearing somewhat contradictory, were changed to “provisional application.”10 Finally, the Conference introduced a new para. 2, concerning the termination of provisional application, which the ILC had dropped in 1965.11 Article 25 was adopted by 87 votes to one, with 13 abstentions.12

Latin American States feared in Vienna that Article 25 would create obligations for signatory States without the legislature’s prior approval. Thus, the obligations created during the period of provisional application could lead to legal relations the validity of which would be questionable (see the reservations in N. 10).13

4 Article 42, para. 1, YBILC 1956 II 116 and 127. 5 YBILC 1962 II 68 .

6 Ibid. 182.

7 YBILC 1966 II 210.

8 See the proposals by Korea, Vietnam, and the US, OR Documents 144, para. 226.

9Since the latter follows a fortiori from the former; see the statement in Vienna by the Philippines delegation, OR 1968 CoW 140, para. 25.

10See the amendment by then Czechoslovakia and Yugoslavia, OR Documents 144, paras. 224; Reuter found the formulation employed by the ILC “quite incorrect”, YBILC 1965 I 106, para. 75; Sir Humphrey Waldock explained in Vienna as Expert Consultant that the proposed changes were inelegant and not commonly used, OR 1968 CoW 145, para. 17.

11See the statement in Vienna by the Chairman of the Drafting Committee, Yasseen, OR 1968 CoW 426, para. 24, upon an amendment brought by Belgium, Hungary and Poland. The ILC had considered it su cient that the matter was left to the parties and to the application of Part V of the Convention concerning termination of the treaty, YBILC 1966 II 210, para. 4.

12OR 1969 Plenary 158.

13E.g., the statement by the delegation of Guatemala, OR Plenary 1969 39, para. 53.

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B.INTERPRETATION OF ARTICLE 25

1.Concept of Provisional Application

4Article 25 concerns the situation where a treaty or a part of a treaty is applied provisionally pending its entry into force. The provision o ers a simplified form of obtaining the application of the entire treaty, or of certain provisions, for a limited period of time. A treaty’s provisional application refers to its temporal application, though not to its e ects:14 the latter will be “definite” and enforceable, as intended by the treaty, and cannot subsequently be called in question in view of the “provisional” nature of the treaty. Put di erently, if the future parties provisionally apply the treaty, they will to this extent be subject to the rule pacta sunt servanda (Article 26, q.v.).15

5A treaty’s provisional application implies that the treaty is subject to conditions for its entry into force, e.g., that the treaty is to receive the required parliamentary approbation or to acquire a certain number of States parties.16 Provisional application is thus to be distinguished from the treaty’s definite entry into force as in Article 24 (q.v.) which will occur later—upon its ratification, acceptance, approval or accession or even signature17—or, perhaps, not at all.

This conceptual distinction between entry into force and provisional application transpires twice in Article 25, i.e., (i) where reference is made to “negotiating States” (N. 7); and (ii) in particular in para. 2 (N. 8), where it is stated that a State accepting the provisional application may eventually “decide not to become a party to the treaty.” The term “party” is defined in Article 2, subpara. 1 (g) (q.v., N. 48).18

6It follows from the freedom of States to conclude treaties in maiore minus that they may at any time decide that a treaty, or certain of its provisions, applies provisionally.19 The legal basis for provisional application will be provided in the treaty itself, or in a separate agreement concluded between the States

14See the statement by Rosenne of the Israeli delegation, OR 1968 CoW 142, para. 44. In the ILC, Waldock considered the term “temporary application” to be more appropriate, YBILC 1965 I 113, para. 58.

15See Mathy, Article 25, N. 25–26.

16ILC Report 1966, YBILC 1966 II 210, para. 1.

17E.g., Articles 14, 15 and 24 (q.v.). The conceptual distinction between provisional application and entry into force upon signature troubled the ILC during its discussions in 1962 and 1965; see Ago in the ILC, YBILC 1965 I 109, para. 6.

18Statement by the Canadian delegation, OR 1969 Plenary 42, para. 80.

19For which reason an express formulation of this principle was considered unnecessary at the Vienna Conference, see the statement by the US delegation, OR 1968 CoW 140, para. 23. Critically Fischer/Köck, N. 236 (“Notmassnahme für dringende Fälle”).

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concerned when negotiating and adopting the text (N. 7).20 Provisional application is also possible between certain States, and even if the treaty has already entered into force between other States.21

Partial provisional application of a multilateral treaty, i.e., among some States inter se, is possible where the treaty lends itself to a fragmentation of treaty relations and other future parties will not be a ected. Conversely, provisional application appears di cult in the case of so-called integral treaties (e.g., on human rights) which are to be applied collectively by all treaty parties.

2. Conditions of Provisional Application (Para. 1)
Article 25, applying to bior multilateral treaties, presupposes the consent	7
of States on the period and nature of the intended provisional application of
a treaty. Such consent may be given in two ways. Either, the treaty itself so
provides, i.e., there will be a clause in the treaty providing for its provisional
application (subpara. 1 [a]), or the negotiating States have in some other
manner so agreed, e.g., by means of a concomitant or subsequent agreement
(subpara. 1 [b]).22 Whether or not such an intention prevails, is a matter of
interpretation according to Articles 31 and 32 (q.v.).
3. Termination (Para. 2)
Para. 2 applies most likely to multilateral treaties (mutatis mutandis to	8
bilateral treaties). It envisages the situation where the provisional applica-
tion of a treaty or a part of a treaty shall be terminated. This provision

o ers protection in particular to the State whose domestic legislature fails to approve the treaty which is already being provisionally applied.23 The procedure envisaged is that the State notifies the other States between which the treaty is being applied provisionally of its intention not to become a party to the treaty. Termination brings to an end any e ects which the treaty has had with respect to a State making the notification as well as the other notified States. The treaty may nevertheless continue to be provisionally applied, or may even have entered into force, between other States inter se (N. 6).24 Since the e ects of provisional application are “definite” (N. 4),

20ILC Report 1966, YBILC 1966 II 210, para. 1. In the ILC, Briggs spoke of “an ancillary or collateral agreement”, YBILC 1965 I 109, para. 4.

21Statement in Vienna by Vallat of the UK delegation, OR 1969 Plenary 40, para. 56; Sinclair, Vienna Convention 46.

22According to Article 2, subpara. 1(e) (q.v., N. 40–42), a negotiating State is one which took part in the drawing up and adoption of the text of the treaty.

23Statement in Vienna by the Expert Consultant, Sir Humphrey Waldock, OR 1969 Plenary 43, para. 89.

24See Waldock in the ILC, YBILC 1965 I 106, para. 73; the ILC Report 1962, YBILC 1962 II 182, para. 2.

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the results of any notification will be ex nunc rather than ex tunc (unless the treaty provides di erently).25 Article 25 thus corresponds with the general regime of the Convention concerning the e ects of termination of a treaty (Article 70, q.v.).26

Article 25 appears misleading when it links the termination of provisional application with the State’s “intention not to become a party to the treaty”. Notification as in para. 2 cannot exclude subsequent entry into force of the treaty for that State.27 It is conceivable that a State encountering domestic di culties—e.g., protracted debate in the national parliament—withdraws from provisional application in order to await approval from the domestic organs leading to the formal entry into force of the treaty for that State.

9The procedure of notification in para. 2 (N. 8) is subject to an exception, namely if the treaty provides otherwise or the negotiating States have otherwise agreed. This formulation has been criticised to the extent that, if a State informs other States that it no longer wishes provisionally to apply the treaty, it is inconceivable that the treaty can provide di erently.28 However, the criticism would be searching too far. This exception merely envisages the case where a notification procedure becomes unnecessary inasmuch as the treaty itself or a separate agreement of States provides, for instance, for particular date when the provisional application shall terminate.

For instance, it may be provided in the treaty to terminate provisional application on a particular date; or after a particular period of time; or if the treaty does not attract a particular number of ratifications or accessions. Notification before this date remains possible.29

C. RESERVATIONS

10Colombia attached the reservation to Article 25 according to which its constitution excludes the provisional application of treaties (N. 3 i.f.). Costa Rica, Guatemala and Peru made similar reservations. Objections filed by various States in respect of these reservations by Austria, Denmark, Finland, Germany and Sweden did not, however, appear to wish to preclude the entry into force of the Convention between the various States. (see Reservations and Declarations to the Convention and Objections Thereto).

25See the question put by the Italian delegation in Vienna, OR 1969 Plenary 42, para. 83.

26See the Note of the Directorate of Public International Law of the Swiss Foreign Ministry of 4 April 2003, SZIER 5 (2004) 669.

27See the statement in Vienna by the Greek delegation, OR 1969 Plenary 41, para. 75.

28Statement in Vienna by Elias of the Nigerian delegation, ibid. 40, para. 65; the reply by Yasseen, Chairman of the Drafting Committee, ibid. para. 66; Lefeber, Provisional Application 87.

29But see Lefeber, ibid. (“interesting caveat”).

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D. CONTEXT
1. Relationship to Other Provisions
Article 25 di ers from Article 24 (q.v.) which concerns the definite entry		11
into force of treaties.30 Furthermore, it di ers from Article 18 (q.v.), which
requires a particular conduct “not to defeat the object and purpose of a treaty”
which goes less far than the provisional application envisaged in Article 25.31
Furthermore, Article 25 is governed by pacta sunt servanda as in Article 26
(N. 7). Finally, Article 25 di ers from Article 28 (q.v. N. 11) which presup-
poses a treaty’s entry into force (N. 5).
2. Customary Basis of Article 25
Article 25, enunciating one of a number of aspects of the freedom of States		12
to conclude treaties, indubitably reflects an established customary rule of
international law.32 A confirmation herefor can be seen in the final vote of
the Vienna Conference; the not insignificant number of abstentions may be
explained with the constitutional di culties feared by Latin American States
(N. 3). Article 25 has since been invoked qua customary law in the Kuwait
v. Aminoil Arbitration.33
E. APPRECIATION
Article 25 o ers an example of an ILC draft proposal which underwent con-		13
siderable change at the Vienna Conference (N. 3). The question arises whether

in light of the principles enshrined in Article 24 (q.v.) a further provision was at all necessary concerning provisional application.34 It is true that Article 25 follows a fortiori from Article 24. However, given the often considerable delays in the entry into force of treaties, on the one hand, and the frequency in daily practice of provisional application, on the other, an express reference to the basic principles appears welcome.35 Article 25 furthermore demonstrates

30Waldock Report IV, YBILC 1965 II 58, para. 1.

31See also the opinion of the US Department of State, AJIL 74 (1980) 933.

32Statement in the ILC by Tunkin, YBILC 1965 I 110, para. 28; the observation by the US Government to the ILC, YBILC 1965 II 58. Mathy, Article 25, N. 2–3, considers it possible that para. 1 (“première partie”) is crystallising into customary law, whereas para. 2 (“seconde parties”) amounts to progressive development.

33ILR 66 (1984) 568.

34See the observation in Vienna by Tsuruoka of the Japanese delegation, OR 1968 CoW 142, para. 1.

35Mathy, Article 25, N. 7, writes here of the “triomphe de l’application provisoire dans de grandes conventions de codification”.

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the flexibility which States enjoy in view of a forthcoming treaty.36 States are also free to disregard the possibilities stated in Article 25, if on constitutional grounds they cannot accept to be bound provisionally.37 Finally, Article 25 may prove useful in that it enables States experiencing domestic di culties with the ratification of the treaty, to demonstrate the legitimacy of the practice of provisional application.38 As a result, it would go too far to state that Article 25 degrades parliamentary approval to a mere formality.39

36Vignes, AFDI 18 (1972) 192 (“caractère d’indication”).

37See the observation by the Canadian delegation in Vienna, OR Plenary 1969 42, para. 80.

38Statement by Jiménez de Aréchaga in the ILC, YBILC 1965 I 112, para. 50.

39See Verdross/Simma N. 718; Lefeber, Provisional Application 82 (“the instrument lends itself to abuse”).

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PART III

OBSERVANCE, APPLICATION AND INTERPRETATION OF TREATIES

Section . Observance of Treaties