An obligation similar in nature to a contract, arising not from an agreement of the parties but from some relation between them or from a voluntary act of one of them. Also, a situation imposed by law to prevent unjust enrichment or injustice and not dependent on agreement of the parties to the contract.

a contract created by law for reasons of justice without any expression of assent

a contract that exists by order of a court, not by agreement of the parties

a duty imposed by law upon a person who has obtained property or services where reason, common sense, and justice dictate that payment should be made therefor

an obligation that is imposed by the courts to avoid injustice or unjust enrichment

A situation in which there arises a legal duty that does not rest upon a promise, but does involve the payment of money.

A contract implied by law, as a matter of equity, when no actual contract exists.

Application of contract rules of law to parties that do not have a contractual relationship.