INTRODUCTION
Whereas Arts. 14 to 17 CISG deal with the offer, Arts. 18 to 23 CISG deal with the acceptance. Art. 18(1) CISG defines the acceptance in general. This provision is in large part supplemented by Art. 19 CISG, which deals with the substantive contents of an acceptance. By contrast, Art. 18(2) and (3) CISG is concerned with the communication of the acceptance and the conditions under which the offeree may be dispensed of such communication. It is thereby supplemented by Art. 20 CISG for the computation of applicable time periods and by Art. 21 CISG with respect to late acceptances. Whereas Art. 23 CISG may be regarded as the conclusion of Part II of the CISG, defining the moment when a contract is concluded, Art. 24 CISG defines for both offer and acceptance when a certain statement reaches the addressee within the meaning of the CISG.
ARTICLE 18(1) CISG – MEANING OF ACCEPTANCE
Article 18(1) CISG substantially corresponds to Art. 2:204 PECL, defining in rather broad terms the meaning of acceptance, which may be express or implied by conduct. Both provisions do, however, clearly deny that silence or inactivity per se may constitute an acceptance. Art. 2:204 PECL thereby reconfirms the principle that in commercial dealings silence in itself does not have legal relevance.
ARTICLE 18(2) CISG – EFFECTIVENESS OF ACCEPTANCE
Reasonable Time
According to Art. 18(2) CISG, an acceptance must reach the offeror within the time open for its acceptance.