West's Encyclopedia of American Law | Quasi Contract

An obligation that the law creates in the absence of an agreement between the parties. It is invoked by the courts where UNJUST ENRICHMENT, which occurs when a person retains money or benefits that in all fairness belong to another, would exist without judicial relief.

A quasi contract is a contract that exists by order of a court, not by agreement of the parties. Courts create quasi contracts to avoid the unjust enrichment of a party in a dispute over payment for a good or service. In some cases a party who has suffered a loss in a business relationship may not be able to recover for the loss without evidence of a contract or some legally recognized agreement. To avoid this unjust result, courts create a fictitious agreement where no legally enforceable agreement exists.

To illustrate, assume that a homebuilder has built a house on...