Concept
Express and Implied Promises
Manifestation of mutual assent and intent to be bound
Express and Implied Promises
A promise does not have to be spoken or written to bind. The Restatement (Second) of Contracts § 4 says that a promise may be stated in words, oral or written, or may be inferred wholly or partly from conduct.1 The rule follows from the objective test studied earlier. If assent is judged by what a reasonable person would take the outward behavior to mean, the form of that behavior cannot decide whether a commitment was made. People often commit by what they do, and a rule that recognized only formal statements would leave out a large share of real agreements. The section therefore teaches how conduct can carry a promise, how that kind of contract differs from a remedy that merely resembles it, and how context decides which side of the line a set of facts falls on.
Promises Inferred From Conduct
A promise stated in words is an express promise, and a promise inferred from conduct is an implied one. When the conduct is enough to show that the parties meant to make a contract, the result is a contract implied in fact. It is an actual contract, with the same legal nature and effect as an express one, and the only difference lies in how the agreement is proved: by circumstantial evidence of conduct instead of by written or spoken terms.2 The same logic extends to terms. In Foley v. Interactive Data Corp., an employee argued that his employer's conduct limited its right to fire him even though no express term said so, and the court explained that implied-in-fact terms ordinarily stand on equal footing with express terms.3 The court held that the employee had pleaded facts which, if proved, could let a jury find such an implied agreement, and that he was entitled to try to prove them.4
The reason for treating implied contracts as fully binding is that the law looks at the message, not the medium. Suppose a man slips on his stairs, is conscious and fully able to decide, and calls an ambulance, which takes him to the hospital. No one mentions payment. A reasonable person in his position, and a reasonable ambulance company in theirs, understands that ambulances do not run for free, so the conduct in its context carries a promise to pay, and a contract is implied in fact.5 Change what the conduct signals and the answer changes with it. If a stranger performs a service that a reasonable recipient would take as a gift, the same silence about payment implies no promise at all, a point developed below with a street musician.
Implied in Fact Versus Quasi-Contract
Two labels sound alike and are easy to confuse. A contract implied in fact rests on the parties' manifested assent, which has been shown by conduct instead of words. A quasi-contract, also called a contract implied in law, is not a contract at all. It is a legal fiction, a duty imposed to prevent one person from keeping a benefit unjustly at another's expense, and it operates without regard to any assent.7 The distinction matters because the first needs everything a contract needs, including mutual assent, while the second needs only an unjust retention of a benefit. Suppose a farmer falls suddenly ill and a neighbor pays to care for his cows. The sick farmer made no promise, so no contract exists, yet a court may order reimbursement under the restitution theory that began as quasi-contract.8
Several differences follow from that structure. An implied-in-fact claim must satisfy every requirement of a real contract.9 A practical way to sort the two is to ask whether the recipient requested the services or property. When a person requests another to perform services, the law infers a bargain to pay, and the claim is on an implied-in-fact contract.10 Where the recipient made no request, only restitution may be available. The two theories can also diverge in result. If a payer mistakenly sends money to the wrong person, the payer can recover it for unjust enrichment, but cannot recover on an implied-in-fact contract, because nothing in the circumstances suggests the money was paid as part of a real agreement.11 Restitution also does not reach a benefit forced on someone: a pool builder who builds a pool in the yard of a traveler who never agreed to it cannot demand payment.12
Reading Conduct in Context
Whether conduct implies a promise depends on what a reasonable person would understand from it in its setting. Take a street musician who plays for passersby with a hat on the sidewalk, and a listener, Mel, who enjoys the music and even asks for an encore. The ordinary expectation is that such playing is voluntary and the hat invites tips, so a reasonable listener would not conclude that a fee is owed. No contract is formed, and the musician also has no restitution claim, because she conferred the benefit as a volunteer.14 Now change one fact: Mel invites her to come to his picnic and play for him and his friends. The request alters the context, and a reasonable person could now expect payment, so a contract implied in fact may exist.15 The only variable that moved was whether the listener asked for the performance.
The same inquiry governs services accepted without discussion. A person who takes offered services with a reasonable opportunity to reject them, and with reason to believe they are offered with an expectation of compensation, may be found to have promised to pay.16 Services rendered inside a family relationship are presumed to be given without that expectation, while services between non-family members are presumed to carry it, and either presumption can be rebutted.17 The presumptions exist because relatives ordinarily have no reason to think a fee is expected, whereas a stranger who does the same work probably does. Whether conduct implies a contract is ordinarily a question of fact for the trier of fact.18
A missing price does not defeat an implied contract. When a contract, express or implied in fact, leaves out the price, a court interprets the agreement in context to fix it, usually by the provider's customary fee and otherwise by the market value of the service, measured by quantum meruit, which means as much as was earned.19 So if Mel and the musician formed a contract at the picnic, she is entitled to her customary or market fee, which may differ from the $200 she demands.20