Guide to the use of this commentary
The Secretariat Commentary is on the 1978 Draft of the CISG, not the Official Text, which re-numbered most of the articles of the 1978 Draft. The Secretariat Commentary on article 17 of the 1978 Draft is quoted below with the article references contained in this commentary conformed to the numerical sequence of the Official Text, e.g., article 17 [draft counterpart of CISG article 19].
To the extent it is relevant to the Official Text, the
Secretariat Commentary on the 1978 Draft is perhaps the
most authoritative source one can cite. It is the
closest counterpart to an Official Commentary on the
CISG. A match-up of this article of the 1978 Draft with
the version adopted for the Official Text is necessary to
document the relevancy of the Secretariat Commentary on
this article. See the match-up for this article for a
partial validation of citations to this Secretariat
Commentary. This match-up indicates that paragraphs (1) and (2) of article 17 of the
1978 Draft and of CISG article 19 are substantively
identical. Paragraphs (3) of these two texts are
Text of Secretariat Commentary on Article 17 of the 1978 Draft
[draft counterpart of CISG article 19] [Additions or modifications to the offer]
PRIOR UNIFORM LAW
ULF, article 7.
General rule, paragraph (1)
1. Article 17(1) [draft counterpart of CISG article 19(1)] states that a purported acceptance which adds to, limits or otherwise modifies the offer to which it is directed is a rejection of the offer and constitutes a counter-offer.
2. This provision reflects traditional theory that contractual obligations arise out of expressions of mutual agreements. Accordingly, an acceptance must comply exactly with the offer. Should the purported acceptance not agree completely with the offer, there is no acceptance but the making of a counter-offer which requires acceptance by the other party for the formation of a contract.
3. However, the acceptance need not use the exact same words as used in the offer so long as the differences in the wording used in the acceptance would not change the obligations of the parties.
4. Even if the reply makes inquiries or suggests the possibility of additional terms, it may be that the reply does not purport to be an acceptance under article 17(1) [draft counterpart of CISG article 19(1)]. The reply may be an independent communication intended to explore the willingness of the offeror to accept different terms while leaving open the possibility of later acceptance of the offer.
5. This point is of special importance in the light of article 15 [draft counterpart of CISG article 17] which provides that "an offer, even if it is irrevocable, is terminated when a rejection reaches the offeror."
6. Although the explanation for the rule in article 17(1) [draft counterpart of CISG article 19(1)] lies in a widely held view of the nature of a contract, the rule also reflects the reality of the common factual situation in which the offeree is in general agreement with the terms of the offer but wishes to negotiate in regard to certain aspect of it. There are, however, other common factual situations in which the traditional rule, as expressed in article 17(1) [draft counterpart of CISG article 19(1)], does not give desirable results. Article 17(2) [draft counterpart of CISG article 19(2)] creates an exception to article 17(1) [draft counterpart of CISG article 19(1)] in regard to one of these situations.
Non-material alterations, paragraphs (2) and (3)
7. Article 17(2) [draft counterpart of CISG article 19(2)] contains rules dealing with the situation where a reply to an offer is expressed and intended as an acceptance but contains additional or different terms which do not material alter the terms of the offer. Article 17(3) [draft counterpart of CISG article 19(3)] provides that certain terms are normally to be considered as material.
8. In most cases in which a reply purports to be an acceptance the offeree does not consider the additional or different terms to be material alterations of the offer. This is particularly the case where the parties do not enter into formal negotiations but communicate with one another by means of an exchange of telegrams, telex or the like or by the exchange of an order form and an acceptance form.
9. If the additional or different terms do not in fact materially alter the terms of the offer, the reply constitutes an acceptance and, according to article 21 [draft counterpart of CISG article 23], a contract is concluded on its receipt. In such a case, the terms of the contract are the terms of the offer with the modifications contained in the acceptance.
10. Even if the additional or different terms do not materially alter the terms of the offer, the offeror may object to them. In such a case the reply of the offeree is to be considered as a rejection of the offer rather than as an acceptance.
[Subparagraph (3) of article 17 of the 1978 Draft and its replacement, article 19 of the Official Text provide that additional or different terms of a type specified "are considered to alter the terms materially". Article 17 of the 1978 Draft qualified this rule by providing that it does not apply where "the offeree by virtue of the offer or the particular circumstances of the case has reason to believe [such terms] are acceptable to the offeror". Paragraphs 11 through 14 of the Secretariat Commentary on article 17 of the 1978 Draft interpret this qualification. This qualification was deleted from article 19 of the Official Text. Accordingly, paragraphs 11 through 14 of this Secretariat Commentary are not quoted here.]
15. If the reply contains a material alteration, the reply would not constitute an acceptance but would constitute a counter-offer. If the original offeror responds to this reply by shipping the goods or paying the price, a contract may eventually be formed by notice to the original offeree of the shipment or payment. In such a case the terms of the contract would be those of the counter-offer, including the additional or different term (OFFICIAL RECORDS, p. 24).