Contract - Elements - Mutual Assent - Offer and Acceptance

Offer and Acceptance

The most important feature of a contract is that one party makes an offer for an arrangement that another accepts. This can be called a concurrence of wills or consensus ad idem (meeting of the minds) of two or more parties. The concept is somewhat contested. The obvious objection is that a court cannot read minds and the existence or otherwise of agreement is judged objectively, with only limited room for questioning subjective intention: see Smith v. Hughes. Richard Austen-Baker has suggested that the perpetuation of the idea of 'meeting of minds' may come from a misunderstanding of the Latin term 'consensus ad idem', which actually means 'agreement to the thing'. There must be evidence that the parties had each, from an objective perspective, engaged in conduct manifesting their assent, and a contract will be formed when the parties have met such a requirement. An objective perspective means that it is only necessary that somebody gives the impression of offering or accepting contractual terms in the eyes of a reasonable person, not that they actually did want to form a contract.

The case of Carlill v Carbolic Smoke Ball Company is an example of a 'unilateral contract'. The term unilateral contract is used in contract law although ultimately there is an offerer and an offeree and a consideration (which may be an act), and in Australian Mills v The Commonwealth, the High Court of Australia considered the term "unscientific and misleading". Obligations are only imposed upon one party upon acceptance by performance of a condition. In the United States, the general rule is that in "case of doubt, an offer is interpreted as inviting the offeree to accept either by promising to perform what the offer requests or by rendering the performance, as the offeree chooses."

Offer and acceptance does not always need to be expressed orally or in writing. An implied contract is one in which some of the terms are not expressed in words. This can take two forms. A contract which is implied in fact is one in which the circumstances imply that parties have reached an agreement even though they have not done so expressly. For example, by going to a doctor for a checkup, a patient agrees that he will pay a fair price for the service. If one refuses to pay after being examined, the patient has breached a contract implied in fact. A contract which is implied in law is also called a quasi-contract, because it is not in fact a contract; rather, it is a means for the courts to remedy situations in which one party would be unjustly enriched were he or she not required to compensate the other. For example, a plumber accidentally installs a sprinkler system in the lawn of the wrong house. The owner of the house had learned the previous day that his neighbor was getting new sprinklers. That morning, he sees the plumber installing them in his lawn. Pleased at the mistake, he says nothing, and then refuses to pay when the plumber delivers the bill. Will the man be held liable for payment? Yes, if it could be proven that the man knew that the sprinklers were being installed mistakenly, the court would make him pay because of a quasi-contract. If that knowledge could not be proven, he would not be liable. Such a claim is also referred to as "quantum meruit".