With every offer, there either is or isn't an acceptance. Seems simple enough, right? Of course it isn't though in the land of law school.
By law (or again, at least in Professor Sorensen's words), an acceptance is defined as the manifestation of assent by the offeree to an offer, made in the mode/manner/medium allowed or required by the offer. In other words, an acceptance is an expression through either a returned promise or performance to show that the offer is agreed upon in the specified mode/manner/medium that is stated by the offeror. An acceptance mus be responsive, communicated, and committed.
The mode describes whether the offeree must accept by making a promise (bilateral) or accept by performance of a specified task (unilateral). The manner of acceptance is the way in which the promise or performance is undertaken (i.e. in writing, orally, standing on one foot). The medium is the form in which an acceptance is communicated to the offeror, such as mail, email, or in person.
There are a few rules in regards to the responsiveness of an acceptance. These include:
- Must be made with knowledge of the offer first.
- In any unilateral bargain, a promise made for a performance returned, if the offeree starts performance without knowledge of the offer but finishes AFTER knowledge is learned, it is considered an acceptance.
- Must be a "mirror image" of the offer in regards to the mode, manner, and medium as stated by the offeror, making them the master of their offer, as well as to the terms.
- An offer might allow acceptance by any mode, manner, or medium, but must be done as required if specified in the offer.
- If the offer proposes a unilateral bargain, acceptance can only be made with the completion of the performance.
- If the offer allows the acceptance by either promise or performance, starting the performance is an acceptance.