For there to be an acceptance the offeree must in one way or

another indicate “assent” to the offer. The mere acknowledgement of

receipt of the offer, or an expression of interest in it, is not sufficient.

Furthermore, the assent must be unconditional, i.e. it cannot be made

dependent on some further step to be taken by either the offeror (e.g.

“Our acceptance is subject to your final approval”) or the offeree (e.g.

“We hereby accept the terms of the contract as set forth in your

Memorandum and undertake to submit the contract to our Board for

approval within the next two weeks”). Finally, the purported

acceptance must contain no variation of the terms of the offer or at

least none which materially alters them (see Art. 2.1.11).

Provided that the offer does not impose any particular mode of

acceptance, the indication of assent may either be made by an express

statement or be inferred from the conduct of the offeree. Para. (1) of

this article does not specify the form such conduct should assume:

most often it will consist in acts of performance, such as the payment

of an advance on the price, the shipment of goods or the beginning of

work at the site, etc.

44

By stating that “[s]ilence or inactivity does not in itself amount to

acceptance”, para. (1) makes it clear that as a rule mere silence or

inactivity on the part of the offeree does not allow the inference that

the offeree assents to the offer. The situation is different if the parties

themselves agree that silence shall amount to acceptance, or if there

exists a course of dealing or usage to that effect. In no event, however,

is it sufficient for the offeror to state unilaterally in its offer that the

offer will be deemed to have been accepted in the absence of any reply

from the offeree. Since it is the offeror who takes the initiative by

proposing the conclusion of the contract, the offeree is free not only to

accept or not to accept the offer, but also simply to ignore it.

I l l u s t r a t i o n s

1. A requests B to set out the conditions for the renewal of a

contract for the supply of wine, due to expire on 31 December. In

its offer B includes a provision stating that “if we have not heard

from you at the latest by the end of November, we will assume that

you have agreed to renew the contract on the conditions as

indicated above”. A finds the proposed conditions totally

unacceptable and does not even reply. The former contract expires

on the fixed date without a new contract having been agreed

between the parties.

2. Under a long-term agreement for the supply of wine B regularly

met A’s orders without expressly confirming its acceptance. On 15

November A orders a large stock for New Year. B does not reply,

nor does it deliver at the requested time. B is in breach since, in

accordance with the practice established between the parties, B’s

silence in regard to A’s order amounts to an acceptance.

According to para. (2) an acceptance becomes effective at the

moment the indication of assent reaches the offeror (see Art. 1.10(2)).

For the definition of “reaches” see Art. 1.10(3). The reason for the

adoption of the “receipt” principle in preference to the “dispatch”

principle is that the risk of transmission is better placed on the offeree

than on the offeror, since it is the former who chooses the means of

communication, who knows whether the chosen means of communication

is subject to special risks or delay, and who is consequently

best able to take measures to ensure that the acceptance reaches its

destination.

45

As a rule, an acceptance by means of mere conduct likewise

becomes effective only when notice thereof reaches the offeror. It

should be noted, however, that special notice to this effect by the

offeree will be necessary only in cases where the conduct will not of

itself give notice of acceptance to the offeror within a reasonable

period of time. In all other cases, e.g. where the conduct consists in

the payment of the price, or the shipment of the goods by air or by

some other rapid mode of transportation, the same effect may well be

achieved simply by the bank or the carrier informing the offeror of the

funds transfer or of the consignment of the goods.

An exception to the general rule of para. (2) is to be found in the

cases envisaged in para. (3), i.e. where “by virtue of the offer or as a

result of practices which the parties have established between

themselves or of usage, the offeree may indicate assent by performing

an act without notice to the offeror”. In such cases the acceptance is

effective at the moment the act is performed, irrespective of whether

or not the offeror is promptly informed thereof.

I l l u s t r a t i o n s

3. A asks B to write a special program for the setting up of a

data bank. Without giving A notice of acceptance, B begins to write

the program and, after its completion, insists on payment in

accordance with the terms set out in A’s offer. B is not entitled to

payment since B’s purported acceptance of A’s offer never became

effective as B never notified A of it.

4. The facts are the same as in Illustration 3, the difference being

that in the offer B is informed of A’s absence for the following two

weeks, and that if B intends to accept the offer B should begin

writing the program immediately so as to save time. The contract is

concluded once B begins to perform, even if B fails to inform A

thereof either immediately or at a later stage.

This article corresponds to paras. (1), (2) first part and (3) of

Art. 18 CISG.