Written by attorneys · grounded in primary & secondary sources — see below
An obligation or right arising by operation of law as if from a contract though no actual agreement exists. The fiction supports restitution to prevent unjust enrichment when one party confers a measurable benefit on another under circumstances making retention unfair.
Sources & Authorities
How it applies
Common Examples
2
Broken Engagement and Reliance Losses
Quest Quail and Quinlan Quezada became engaged after working together at a startup. Quest quit her job and spent months managing Quinlan's company books and paying off business debts in direct reliance on repeated assurances that the contributions formed part of their upcoming marriage. When Quinlan called off the wedding, Quest sued for breach of promise to marry seeking recovery of her actual expenditures and opportunity costs. The court treated the claim as a quasi ex contractu action and awarded restitution measured by the value of the benefits Quinlan retained.
Emergency Medical Services to Unconscious Patient
Quincy Quan collapsed unconscious on a public street. A passing physician provided emergency treatment at the scene and later billed Quincy for the reasonable value of the services. Quincy refused payment arguing no contract had ever been formed. The court imposed liability under a quasi ex contractu theory because the physician conferred a measurable benefit under circumstances making retention of the value without payment unjust.
Put it into practice
Test Yourself
9
Practice Questions5
· 1 primary source
Select any source to read its text and confirm it supports the definition.
Common Law
Casebooks
Study Supplements
Dictionaries
Cotnam v. Wisdom83 Ark. 601, 104 S.W. 164
Common questions
Frequently Asked
4
How does quasi ex contractu differ from a contract implied in fact?+
A contract implied in fact rests on the parties' actual conduct showing mutual assent to an agreement. Quasi ex contractu rests on no evidence of agreement at all. It is a pure legal fiction created solely to support restitution when one party has been unjustly enriched.
Supporting sources
What remedy does quasi ex contractu provide in a breach of promise to marry case?+
In jurisdictions that still recognize the action, recovery is limited to actual damages such as expenditures made in preparation for marriage plus loss to reputation, mental anguish, and injury to health. Recovery for loss of expected benefits such as social or financial position is not allowed.
Supporting sources
Can a party recover in quasi ex contractu when an express contract exists?+
No. Quasi ex contractu applies only when no enforceable contract governs the transaction. If an express contract covers the same subject matter, the plaintiff must sue on the contract rather than on the equitable theory of unjust enrichment.
Supporting sources
What must a plaintiff prove to recover under a quasi ex contractu theory?+
The plaintiff must show that a benefit was conferred on the defendant, that the defendant appreciated or accepted the benefit, and that retention of the benefit without payment would be unjust under the circumstances.
Supporting sources
ContractsFormation of contracts · Indefiniteness and absence of termsUBEIntermediate