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Cite as Rajski, in Bianca-Bonell Commentary on the International Sales Law, Giuffrè: Milan (1987) 121-124. Reproduced with permission of Dott. A Giuffrè Editore, S.p.A.

Article 11

Jerzi Rajski

1. History of the provision
2. Meaning and purpose of the provision
3. Problems concerning the provision


A contract of sale need not to be concluded in or evidenced by writing and is not subject to any other requirements as to form. It may be proved by any means, including witnesses.

1. History of the provision.

     1.1. - Article 11 establishes a general principle of informality, i.e., that sales contracts are not subject to any formal requirements.

Its antecedents are to be found in Article 15 of ULIS and in Article 3 of ULFC. The first of these articles read:

A contract of sale need not be evidenced by writing and shall not be subject to any other reguirements as to form. In particular, it may be proved by means of witnesses.

Similarly, the second stated:

An offer or an acceptance need not be evidenced by writing and shall not be subject to any other requirement as to form. In particular, they may be proved by means of witnesses.

     1.2. - Some changes have been introduced in the wording of both sentences of Article 11 in order to clarify its meaning and to make more precise its formulation.

The first sentence avoids speaking of «offer» and «acceptance», in order to take into account that some contracts are concluded after protracted negotiations and sometimes even after the intervention of an intermediary. In these cases it may become very difficult to determine which acts constitute the offer and acceptance.

     1.3. - The second sentence of Article 11 fully confirms the principle that any evidence is admissible to prove the conclusion [page 121] of a contract. At the Vienna Conference an amendment was proposed to this provision aimed at introducing a limitation on admissible evidence in cases in which contracting parties had freely: chosen to have a written form. The amendment would have excluded evidence by witnesses unless it were supported by other evidence from the opposing party or circumstantial evidence. It called for some degree of certainty as to facts which could be used to establish a prima facie case. The majority of delegations considered this proposal contradictory to the fundamental principle of the free appreciation of evidence by the judge (see Official Records, II, 270).

2. Meaning and purpose of the provision.

     2.1. - Article 11 establishes as one of the basic rules of the Convention a concept well-known in continental European law: the theory of consensualism. According to this theory contracts are not subject to any specific formal requirements. The parties are entirely free to determine the form of their contract of sale. The majority of States accept this principle, although sometimes it is modified to a certain degree by the introduction of formal requirements provided for certain purpose (see, e.g., DÖLLE, Einheitliches Kaufrecht, 86 et seq.; ZWEIGERT-KÖTZ, An Introduction to Comparative Law, Amsterdam (North Holland Publishing Co.), 1973, II, 37 et seq.).

The theory of consensualism has also been widely adopted in international commercial practice, and by various international interstate or professional organizations and associations in their formulations of general conditions for sales contracts. Among them are the general conditions elaborated by the U.N. Economic Commission for Europe (see, e.g., Article 7 of the following Economic Commission for Europe General Condition of Sale: For Potatoes of 1980; For Fresh Fruit and Vegetables Including Citrus Fruit of 1979; For Dry, Shelled and Unshelled, and Dried Fruit of 1979). Moreover, in its comments on Article 11 the International Chamber of Commerce stressed the importance of consensualism because a considerable part of international trade relies on unwritten contracts. Nevertheless, some large enterprises tend to put all their transactions in writing. [page 122]

The law of some States however, rigorously requires a written form for all international sales contracts (see commentary on Article 12, infra, § 2.1). This is why Article 11 does not apply in cases falling under Article 12.

     2.2. - According to Article 11, the contract of sale is not subject to any requirement as to form. This means that any such requirement prescribed by the domestic law of the Contracting State does not apply, except as pursuant to Article 12, to contracts subject to the Convention, irrespective of the nature of the requirement and of the purposes it is supposed to serve.

     2.3. - The first sentence of Article 11 implies the second sentence. The second sentence confirms that the rule established in the first sentence also applies for procedural purposes. This means that the rule of freedom of contract form is fully enforceable in appropriate arbitration or judicial proceedings. Thus, except as pursuant to Article 12, any restriction or limitation established by the law of any Contracting State is not applicable to cases governed by the Convention.

3. Problems concerning the provision.

     3.1. - The provision of Article 11 is of a non-mandatory nature. The parties may agree on other requirements concerning the form of the contract, or of any declaration connected with it. They may depart from the provision of Article 11 either wholly or partially, expressly or implicitly (see Article 6). Article 11 may also be excluded by usages to which the parties have agreed or from any practices which they have established between themselves (see Article 9).

In fact, the situations envisaged above occur frequently in international commercial practice. Some offers contain stipulations that an acceptance must be in writing. Sometimes the offeree conditions conclusion of the contract on written confirmation by the offeror. Such stipulations are included also in various drafts of general conditions of sales prepared by different international organizations or professional associations (see, e.g., paragraphs 2.1. of the following Economic Commission for Europe [page 123] General Conditions: For the Supply of Plant and Machinery for Export No. 188; For the Supply of Plant and Machinery for Import, No. 188A; For the Erection of Plant and Machinery Abroad, No. 188D and No. 574D; of Sale for the Import and Export of Durable Consumer Goods and Other Engineering Stock Articles, No. 730).

     3.2. - A provision in the parties agreement providing for a contractual formality may lose its effect by virtue of a subsequent waiver. This is the necessary result of the principle of informality of transactions embodied in Article 11, that a subsequent agreement by the parties is not subject to any formal requirements, and may be proved by any means. For the somewhat different case where one of the party may be precluded by his contract from arresting a contractual provision requiring any modification or termination by agreement of the contract to be in writing, see commentary on Article 29, infra § § 2.4. et seq.. [page 124]

Pace Law School Institute of International Commercial Law - Last updated January 11, 2005
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