Source: http://www.cisg.law.pace.edu/cisg/text/ziegel12.html
Timestamp: 2019-04-26 14:32:53+00:00

Document:
1. Art. 12 constitutes an important exception to Art. 11 and was included at the request of some states (notably the USSR) who felt that countries that regard writing as an essential prerequsite for the enforcement of a contract, or to prove its modification or termination, should be free to exclude Art. 12 and the other relevant provisions of CISG by means of a declaration made pursuant to Art. 96.
First, the declaration can only be made by a state whose legislation requires contracts of sale to be concluded in or evidenced by writing--it cannot therefore be made by jurisdictions such as British Columbia or the United Kingdom that have deleted writing requirements from their sales legislation or have never had it. (Qu. the position where the domestic law only requires writing for some types of sale?).
Secondly, Arts. 12 and 96 are not restricted to writing requirements concerning the contract of sale, its modification or termination but extend to any communication under Pt. II of this convention.
Thirdly, the declaration cannot embrace other types of communication, e.g., a declaration of avoidance of the contract pursuant to Arts. 26 and 59. Presumeably, however, it is open to a state to restrict its declaration to some of the matters enumerated in Art. 12.
Finally, it is not clear what the exact effect of a declaration will be. Obviously it will mean that a writing will be required, but how complete a writing and at what time? Will a signature be essential? Will a communication not in writing be a total nullity or only inadmissible in legal proceedings? Since CISG does not appear to answer these questions, one possibility would to say that the domestic requirements of the declaring state apply. However, this would create difficulties where the states of two or more contracting parties have filed declarations and their domestic writing requirements are not the same. Will they all have to be complied with?
4. In light of the above observations, it should be clear that Art. 12 creates as many difficulties as it purports to resolve (I have only mentioned some of them) and that, in Canada's case, the Provinces should be discouraged from asking for a declaration under Art. 12.

References: Art. 12
 Art. 11
 Art. 12
 Art. 96
 Art. 12
 Art. 12
 Art. 12