Concept
How Assent Is Manifested
Manifestation of mutual assent and intent to be bound
How Assent Is Manifested
The objective test tells a court to read the parties' outward conduct, but it does not say which conduct counts as assent or when it counts. The Restatement (Second) of Contracts answers in a short run of rules, each aimed at a different question: what each party must do (§ 18), in what form assent may be given (§ 19(1)), what the actor must know for conduct to count (§ 19(2)), and what follows when the conduct shows assent that the actor did not really feel (§ 19(3)).1 This section takes them one at a time, because each has its own reason and its own boundary.
Promise or Performance
Mutual assent to an exchange requires that each party either make a promise or begin or render a performance.2 This is the minimum each side must contribute. Mere thinking, hoping, or listening is not enough; each party must commit through a promise, or must start doing the thing requested. The rule ties assent to the exchange the law enforces, since an exchange needs something from both sides, and what each side gives is either a promise or a performance. Where both sides give promises, the contract is bilateral. Where one side gives a promise and the other gives a performance, the contract is unilateral. Chapter 6 returns to how that difference affects acceptance.
Suppose a homeowner, Dana, leaves a voicemail for a painter, Marcus: she will pay $2,400 to have her fence painted by Friday. Marcus calls back and says he will do it. Each party has now made a promise, so the minimum of § 18 is met on both sides. Change the facts slightly. Marcus never calls back, but he arrives on Monday with his ladders and starts scraping the fence. Dana's promise is already on the table, and Marcus has now begun a performance. That also satisfies § 18 for his side, even though he never said a word. Now take the other pole. Marcus listens to the voicemail, mentions it to his spouse, and does nothing else. He has neither promised nor begun to perform, so he has manifested no assent, and no contract forms, however interested he privately was.
Words, Acts, and Silence
The manifestation of assent may be made wholly or partly by written or spoken words, by other acts, or by failure to act.4 The rule is broad because people communicate commitment in many ways, and a law that recognized only signed documents would leave out most of ordinary life. Marcus could have assented by replying "sounds good," by texting a thumbs-up, or, as in the last example, by turning up and beginning work. Each of these is a manifestation, and the law treats them alike once the circumstances show they were meant as assent.
Courts apply the same rule to modern technology. In a case the Eleventh Circuit decided, a homeowner paying a mortgage by phone was told by the automated system that the terms of the payment were posted online and was directed to press 1 to complete the transaction and accept them. Pressing 1 manifested assent to the arbitration agreement in those terms.5 The employment context shows the same thing. In Foley v. Interactive Data Corp. the California Supreme Court explained that courts may look to the parties' conduct to decide whether it demonstrates an implied contract, and that implied-in-fact terms ordinarily stand on the same footing as express terms.6 What counts is the message the conduct conveys, whatever form it takes.
Silence is the weakest form. Although the rule lists a failure to act among the ways assent may be shown, saying nothing is ambiguous in a way that words and affirmative acts are not. A person who stays silent may have agreed, may not have noticed, or may simply have decided to ignore the matter. So a failure to act usually carries assent only where the circumstances, such as a prior course of dealing, make silence a sensible way to say yes. Compare two situations. If Marcus tells Dana in a voicemail that he will paint her fence for $2,400 unless she calls him back, and she never does, her silence does not by itself bind her. If instead Dana has hired Marcus on exactly the same terms every spring for ten years, and he sends his usual confirmation, her silence may be read as assent because her past behavior gave it that meaning.
Intended Conduct and Reason to Know
A party's conduct is not effective as a manifestation of assent unless the party intends to engage in the conduct and knows or has reason to know that the other party may infer assent from it.8 The rule has two parts, and each guards against a different kind of unfairness. The first part, that the actor intends the conduct, screens out movements that are not really the actor's own acts, such as a reflex or an accident. The second part, that the actor knows or has reason to know the other side may infer assent, keeps the objective test from catching someone who acted without realizing that anyone would read the act as a commitment. Without that second part, a person could be bound by conduct that no one in their position would have expected to be taken that way.
An invented auction shows both parts. A veteran bidder at a livestock auction, who knows the auctioneer watches for a nod, nods at a price. The nod is intended, and the bidder has every reason to know it will be read as a bid, so it manifests assent. A tourist wandering into the same room waves to a friend across it. The wave is intended, but the tourist has no reason to know the auctioneer might treat it as a bid, so under § 19(2) it manifests no assent. The conduct is almost identical, and the difference lies in what the actor knew or should have known about how others would read it.
The same reasoning governs online agreements. In Nguyen v. Barnes & Noble Inc. the Ninth Circuit held that a retailer's website terms, available only through a hyperlink at the bottom of each page, did not bind a customer who had never been prompted to agree to them and had not read them.9 The court explained that where the user takes no affirmative step except using the site, validity depends on whether the user had actual or constructive knowledge of the terms.10 Nothing in browsing the site told the customer that this ordinary activity would be read as assent. A click on an "I agree" button after the terms are displayed is the opposite case, because the click announces what it means.
Assent Without Actual Assent
Conduct may manifest assent even though the actor does not in fact assent, and in that event the resulting contract may be voidable because of fraud, duress, mistake, or another invalidating cause.12 Two reasons explain the rule. The first is reliance: the other party can only act on what is shown, so apparent assent has to bind, or no one could safely rely on a signature or a handshake. The second is relief: a person whose apparent assent was produced by deception, coercion, or a mistake the law recognizes should not be stuck with it, so the contract is voidable, meaning the wronged party may choose to avoid it or to affirm it. Formation and validity are separate questions. Under § 19(3) the contract exists first, and the invalidating cause then gives one party the power to undo it.
Suppose a homeowner signs a painting contract after the painter falsely claims to hold the license that local law requires. The signature manifests assent, and the contract is formed. Because the assent was induced by fraud, however, the homeowner may avoid the contract, and the painter, who caused the problem, has no power to cancel it on that ground. Compare a homeowner who signs the same contract, then learns a cheaper painter is available and says that she never really wanted to commit. Her change of heart is not an invalidating cause. Her signature manifested assent, and nothing makes the contract voidable, so she is bound.
Promise or Performance
Every agreement to exchange needs a contribution from each side, and Restatement (Second) of Contracts § 18 states what that contribution must look like: manifestation of mutual assent to an exchange requires that each party either make a promise or begin or render a performance.14 The rule gives each party two routes. A party can commit in words by promising to do something, or can commit by conduct by starting to do the thing the exchange calls for. Thinking favorably about a proposal, privately intending to go along, or simply hearing the other side out falls under neither route, so none of it manifests assent.
The reason for the rule lies in what contract law enforces. The law backs exchanges, and an exchange has two sides, so the law needs something from each side that shows commitment. A promise is a commitment in advance, and a begun or completed performance is a commitment in action. A party who has done neither has given the other side nothing to rely on and nothing to enforce, so there is no reciprocity for the law to protect. The rule also keeps the objective test from stretching too far. That test reads outward conduct, and § 18 identifies which conduct is outward enough to count.
The two routes also explain the distinction between bilateral and unilateral contracts. When each party makes a promise, the parties have exchanged promises, and the contract is bilateral. When one party makes a promise and the other responds by performing, the contract is unilateral, because only one side has promised.15 The Restatement treats the difference as one of the mode of acceptance, with acceptance by promise on one side and acceptance by performance on the other. Bilateral exchanges predominate in practice, and the law presumes that an offeree may accept by promising to do what the offer requests.16 The later treatment of offer and acceptance develops how that choice affects the moment a contract forms, so for now it is enough to see that § 18 permits both.
Suppose a homeowner leaves a voicemail for a landscaper, Tomas, offering $3,000 to regrade and reseed the back lawn by the end of the month. If Tomas calls back and says he will do the job, each party has made a promise, and § 18 is satisfied on both sides. Change the facts so that Tomas never calls but arrives the next morning with a crew and a rented grader. Beginning the invited work is itself a manifestation of assent, because a reasonable homeowner would read the crew's arrival as a commitment to finish the job.17 Tomas has said nothing, yet his conduct supplies the performance that § 18 accepts in place of a promise.
Now consider the pole where the rule withholds assent. Tomas hears the voicemail, mentions it to his business partner, and decides the job looks appealing. He never calls back, never orders materials, and sends no crew. He has neither promised nor begun to perform, so he has manifested no assent to an exchange, however interested he was in private. The two versions of Tomas differ in one fact, which is whether he put anything outward on the table, and that difference decides whether the exchange is formed on his side.
Words, Acts, and Silence
Having settled that each party must promise or perform, the next question is what forms that commitment may take. The Restatement (Second) of Contracts answers broadly: the manifestation of assent may be made wholly or partly by written or spoken words, by other acts, or by failure to act.19 The breadth follows from the objective test already studied. If assent is judged by what a reasonable person would take the conduct to mean, the form of the conduct matters far less than the message it carries. A signed agreement, a spoken "you have a deal," a nod at an auction, and a seller's shipment of the goods ordered can all say yes, and the law treats them alike once the circumstances show that they do. A rule limited to signed documents would leave out most of the agreements people actually make.
The phrase "wholly or partly" also deserves attention, because assent is often spread across several forms at once. Suppose a caterer and a couple agree orally on a menu and a price, and the caterer later emails a deposit invoice, which the couple pay. No single act contains the whole agreement. Words supply the terms, and the payment supplies the confirming conduct. A court reads all of it together, asking what a reasonable person in the other party's position would conclude from the whole course of words and acts.
Silence is the odd item in that list, and it is the weakest form of assent. Words and affirmative acts point one way, while saying nothing is ambiguous: a silent person may have agreed, may not have noticed, or may have decided to ignore the matter altogether. Because of that ambiguity, a failure to act ordinarily does not manifest assent, since a reasonable person would not usually read silence as a promise.20 A second reason is protective. If silence could bind, an offeror could impose a duty to respond on anyone simply by mailing an offer, and the recipient would have to spend time and money rejecting proposals never invited. So when an offeror writes an unsolicited letter saying, "If I do not hear from you by Tuesday, I shall assume you accept," the recipient who stays silent is not bound, and authorities agree that the recipient need not reply.21
The exceptions are narrow, and each depends on circumstances that give silence a meaning it would not otherwise have. Section 69 of the Restatement (Second) of Contracts lists them, and they include a person who takes the benefit of offered services with a reasonable opportunity to reject them and reason to know that payment was expected.22 Suppose a homeowner has used the same lawn service for years without signing anything, and one spring watches from the window as the crew mows. The homeowner knew the service expected payment and could easily have stopped the crew, so the silence amounts to acceptance.23 Prior dealings can have the same effect. In Hobbs v. Massasoit Whip Co. a seller had shipped eelskins to a manufacturer four or five times, and each time the manufacturer had accepted and paid. When another shipment arrived and the manufacturer kept the skins for months without a word, the court held that the jury could treat the silence as acceptance, on the principle that conduct which imports assent is assent in the view of the law, whatever the actual state of mind.24 Given the history, the seller was no stranger sending unwanted goods, and a reasonable seller would expect a rejection if the buyer meant to refuse.25
The two silence examples differ in one fact: whether the surrounding circumstances created an expectation that the recipient would speak if unwilling. The manufacturer in the eelskin case had a pattern of buying that made silence read as yes, while the recipient of the unsolicited letter had no relationship with the sender that gave silence any such meaning. Without that background, the offeror's own declaration cannot turn inaction into agreement.
Intended Conduct and Reason to Know
The objective test lets a party's outward conduct bind them without regard to what they privately thought, so the law needs some limit on which conduct counts. Restatement (Second) of Contracts § 19(2) supplies it: a party's conduct is not effective as a manifestation of assent unless the party intends to engage in the conduct and knows or has reason to know that the other party may infer from it that the party assents.27 The rule has two parts, and each guards against a different kind of unfairness. The first screens out movements that were never really the actor's own choice. The second keeps an objective standard from catching someone who acted without any reason to expect that the act would be read as a commitment.
The first part asks whether the actor intended the conduct itself. Intending the conduct means meaning to do the act, and it does not require wanting the legal consequences that follow.28 A person who deliberately signs a document has intended the signing, even if they never wanted to be bound by it and would be astonished to learn that they are. A person whose arm is jostled so that a pen lands on a signature line has not intended anything, and the resulting mark is not their act in any sense the law cares about. The reason is that contract law holds people to what they chose to do. A reflex or an accident reveals nothing about commitment, so treating it as assent would punish a person for something that was not a choice.
The second part asks what the actor knew or should have known about how others would read the act. This is the accountability principle at work: a party is answerable for deliberate words or conduct made with reason to know that they will create a reasonable impression of assent.29 The vantage point is that of a reasonable person in the position of the other party, and the actor is charged with whatever the actor actually knows or ought to know because of particular experience or superior knowledge.30 That standard explains why the same gesture can bind one person and leave another free. It also supplies the incentive logic behind the rule. Someone who chooses an act and can foresee how it will be taken is the person best placed to avoid the misunderstanding, whereas the observer who relied on it had no means of looking behind the act.
An invented auction shows both parts working together. Suppose an experienced cattle buyer, who knows that this auctioneer watches for a raised catalogue, lifts hers at the opening price. The lift is intentional, and she has every reason to know it will be read as a bid, so it manifests assent. Now suppose a visitor who has wandered in out of the rain waves to a friend across the room. The wave is just as intentional, but the visitor has no reason to know that anyone might treat it as a bid, so § 19(2) says it manifests nothing. The conduct is nearly identical in the two cases, and the only fact that moves the answer is what the actor knew or should have known about how the room would read it. The same analysis produces the ordinary result when a person signs a contract document that was available to read: the signing is voluntary, and anyone who signs a contract knows it will be taken as agreement.
Assent Without Actual Assent
The objective test lets one party rely on what the other has outwardly shown, and that raises an obvious question: what happens when the outward show and the inner state of mind do not match? Restatement (Second) of Contracts § 19(3) answers in two steps. Conduct may manifest assent even though the actor does not in fact assent, and when that happens, the resulting contract may be voidable because of fraud, duress, mistake, or another invalidating cause.32 The first step says a contract is formed. The second step says the law may still let the party whose assent was tainted undo it. Voidable means the contract is valid until the wronged party elects to avoid it, so the choice belongs to that party and not to the other side.
The decision in Lucy v. Zehmer shows the first step at work. The Zehmers insisted that the signed writing selling their farm was a joke, and the court held them bound anyway, because the law imputes to a person an intention corresponding to the reasonable meaning of his words and acts.33 Nothing in the Zehmers' conduct told Lucy that the offer was not serious until after the writing was signed, and a whispered aside to a spouse is a secret the other party could never have seen. The same case also shows what the second step requires. The court noted that the Zehmers had been drinking but not to the point of being unable to understand what they were doing, and that there was no fraud, no misrepresentation, no sharp practice, and no dealing between unequal parties.34 The Zehmers had apparent assent and no invalidating cause, so nothing was left to relieve them.
Two separate reasons support this structure, and they should be kept apart. The first is reliance. A party who is about to rearrange their affairs can look only at what the other side shows, so if apparent assent could be disowned by pointing to a hidden state of mind, no signature or handshake could safely be relied on. The second is fairness to the person whose assent was compromised. Someone who signed because of a lie, a threat, or a mistake the law recognizes did not give the kind of free and informed assent that justifies enforcement. The law therefore gives that person a power to avoid the contract. Defenses of that kind have their own doctrines and are taught elsewhere, but § 19(3) is where they connect to formation. Keeping the two inquiries separate also keeps a bare claim of "I did not really mean it" from standing in for a defense, because a contract can be avoided only on grounds the law recognizes, and unexpressed second thoughts are not among them.
Suppose a homeowner signs a roofing contract after the roofer falsely says that the roof's current condition violates the local code. The signature manifests assent, so the contract exists. Because the homeowner's assent was induced by a misrepresentation, however, the homeowner may choose to avoid it, while the roofer cannot escape the contract by pointing to his own lie. Now change one fact. A different homeowner signs the same contract, learns the next day that a neighbor paid less, and tells the roofer that he never truly wanted to commit. The signature manifested assent, and no fraud, duress, or recognized mistake accompanies it. Regret over the price is not an invalidating cause, and so this homeowner is bound.
Mutual misunderstanding is a different problem, and it should not be confused with assent that is tainted. In Raffles v. Wichelhaus, a buyer and a seller agreed on 125 bales of cotton to arrive on the ship Peerless from Bombay, but two ships bore that name and sailed in different months. Each party had a different ship in mind, and neither knew the other meant something else.35 The court found no agreement on the same thing, and so no contract. Under the Restatement, where the parties attach different meanings to a term and neither knows or has reason to know the other's meaning, neither is bound by the other's meaning, even though the result may be a failure of mutual assent.36 The contrast with § 19(3) is that here nothing outward told either party that the other meant something different, so the manifestations never lined up. In Lucy v. Zehmer the manifestation was clear, and only one side's hidden thoughts differed from it. Where one party's outward words had a single reasonable meaning, that party's undisclosed intention is immaterial, so the contract forms.37