In the event of material uncertainty, the agreement cannot constitute a binding contract. This can happen when the agreement is “vague or ambiguous,” incomplete or constitutes a simple “agreement of agreement.” While a supplier cannot stipulate that silence is considered an acceptance and thus imposes a favourable refusal obligation on the bidder (Felthouse/Bindley (1862) 142 ER 1037), it is possible: to renounce, in some cases, the requirement for notification for adoption – usually where it would not be economically practical to require such notification – as in cases of reward (see , z.B. Carlill) The question of whether there is a consensus is objectively determined (like most things in contract law); In essence, this means that when it appears to a sensible person that the parties have entered into a sufficient agreement, even if one of the parties could have acted under a misunderstanding or sneaked their fingers behind their backs and did not subjectively consider agreeing or making a contractual offer. If acceptance completes the required act (as Carlill proposes), a supplier may apply the general rule once the benefit has begun, but before it is completed. However, in Daulia/Four Millbank, it was proposed that, for unilateral contract offers, the offer be accepted and that a contract be entered into if the deed was clearly commenced. Agreements to conclude a future agreement are not binding. In the United Kingdom, the House of Lords has decided that negotiation agreements are not applicable either. However, in Australia, the Court suggested to Coal Cliff Colliaries that bargaining agreements could be applicable in appropriate circumstances. It is clear that lockout agreements – that is, agreements that are not negotiated with a third party for a specified period – are sufficiently secure and are not cancelled for reasons of uncertainty.
The adoption of unilateral agreements usually takes the form of an act. The question is whether an offer can be revoked once the benefit has been launched, but before it is completed. This problem has not yet been resolved. In Daulia Ltd/Four Millbank, it was argued that acceptance is made as soon as the deeds requested by the bidder have been introduced and the offer could not be subsequently revoked. If it is not possible to give special meaning to the words used in an agreement, it is considered too vague or ambiguous to constitute a contract. As a general rule, the parties must consider the essential conditions of the agreement in order for it to be implemented. Price is generally considered essential (although, in the case of commodity legislation, the agreement is “complete” if the parties do not agree on the price (see z.B s 13 (2) Goods Act (Vic), which requires a reasonable price if no price is set. It is not absolutely necessary for an agreement to be drawn up in detail and it is possible for the parties to designate one of the parties – or a third party – to determine certain issues in the future, provided that the parties themselves do not need to reach an additional agreement. The Court of Appeal held that the clause, to the extent that it relates to the later period, was merely a “consent agreement” and was therefore legally unenforceable. There are cases where it is not possible to clearly identify the offer and acceptance, but it is nevertheless possible to reach an agreement between the parties on the basis of their behaviour. A good example: to be effective, acceptance must be communicated – a mental decision that must be accepted is not enough. The general rule is that an agreement is reached if and where the communication of acceptance is received – with respect to the immediate modes of communication that are accepted is considered to be received when it is given to the supplier (even if they do not read it).