This is “Duress and Undue Influence”, section 10.1 from the book The Legal Environment and Foundations of Business Law (v. 1.0). For details on it (including licensing), click here.


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10.1 Duress and Undue Influence

Learning Objectives

  1. Recognize that if a person makes an agreement under duress (being forced to enter a contract against his or her will), the agreement is void.
  2. Understand what undue influence is and what the typical circumstances are when it arises to make a contract voidable.


When a person is forced to do something against his or her will, that person is said to have been the victim of duressA threat of improper action to induce a person to make a contract.—compulsion. There are two types of duress: physical duress and duress by improper threat. A contract induced by physical violence is void.

Physical Duress

If a person is forced into entering a contract on threat of physical bodily harm, he or she is the victim of physical duressThe threat of physical harm that wrongfully induces a party to contract.. It is defined by the Restatement (Second) of Contracts in Section 174: “If conduct that appears to be a manifestation of assent by a party who does not intend to engage in that conduct is physically compelled by duress, the conduct is not effective as a manifestation of assent.”

Comment (a) to Section 174 provides in part, “This Section involves an application of that principle to those relatively rare situations in which actual physical force has been used to compel a party to appear to assent to a contract.…The essence of this type of duress is that a party is compelled by physical force to do an act that he has no intention of doing. He is, it is sometimes said, ‘a mere mechanical instrument.’ The result is that there is no contract at all, or a ‘void contract’ as distinguished from a voidable one” (emphasis added).

The Restatement is undoubtedly correct that there are “relatively rare situations in which actual physical force” is used to compel assent to a contract. Extortion is a crime.

Duress by Threat

The second kind of duress is duress by threat; it is more common than physical duress. Here the perpetrator threatens the victim, who feels there is no reasonable alternative but to assent to the contract. It renders the contract voidable. This rule contains a number of elements.

First, the threat must be improper. Second, there must be no reasonable alternative. If, for example, a supplier threatens to hold up shipment of necessary goods unless the buyer agrees to pay more than the contract price, this would not be duress if the buyer could purchase identical supplies from someone else. Third, the test for inducement is subjective. It does not matter that the person threatened is unusually timid or that a reasonable person would not have felt threatened. The question is whether the threat in fact induced assent by the victim. Such facts as the victim’s belief that the threatener had the ability to carry out the threat and the length of time between the threat and assent are relevant in determining whether the threat did prompt the assent.

There are many types of improper threats that might induce a party to enter into a contract: threats to commit a crime or a tort (e.g., bodily harm or taking of property), to instigate criminal prosecution, to instigate civil proceedings when a threat is made in bad faith, to breach a “duty of good faith and fair dealing under a contract with the recipient,” or to disclose embarrassing details about a person’s private life.

Jack buys a car from a local used-car salesman, Mr. Olson, and the next day realizes he bought a lemon. He threatens to break windows in Olson’s showroom if Olson does not buy the car back for $2,150, the purchase price. Mr. Olson agrees. The agreement is voidable, even though the underlying deal is fair, if Olson feels he has no reasonable alternative and is frightened into agreeing. Suppose Jack knows that Olson has been tampering with his cars’ odometers, a federal offense, and threatens to have Olson prosecuted if he will not repurchase the car. Even though Olson may be guilty, this threat makes the repurchase contract voidable, because it is a misuse for personal ends of a power (to go to the police) given each of us for other purposes. If these threats failed, suppose Jack then tells Olson, “I’m going to haul you into court and sue your pants off.” If Jack means he will sue for his purchase price, this is not an improper threat, because everyone has the right to use the courts to gain what they think is rightfully theirs. But if Jack meant that he would fabricate damages done him by a (falsely) claimed odometer manipulation, that would be an improper threat. Although Olson could defend against the suit, his reputation would suffer in the meantime from his being accused of odometer tampering.

A threat to breach a contract that induces the victim to sign a new contract could be improper. Suppose that as part of the original purchase price, Olson agrees to make all necessary repairs and replace all failed parts for the first ninety days. At the end of one month, the transmission dies, and Jack demands a replacement. Olson refuses to repair the car unless Jack signs a contract agreeing to buy his next car from Olson. Whether this threat is improper depends on whether Jack has a reasonable alternative; if a replacement transmission is readily available and Jack has the funds to pay for it, he might have an alternative in suing Olson in small claims court for the cost. But if Jack needs the car immediately and he is impecunious, then the threat would be improper and the contract voidable. A threat to breach a contract is not necessarily improper, however. It depends on whether the new contract is fair and equitable because of unanticipated circumstances. If, for example, Olson discovers that he must purchase a replacement transmission at three times the anticipated cost, his threat to hold up work unless Jack agrees to pay for it might be reasonable.

Undue Influence

The Restatement of Contracts (Second) characterizes undue influenceImproper use of power or trust in a way that deprives a person of free will and substitutes another’s objective. as “unfair persuasion.”Restatement (Second) of Contracts, Section 177. It is a milder form of duress than physical harm or threats. The unfairness does not lie in any misrepresentation; rather, it occurs when the victim is under the domination of the persuader or is one who, in view of the relationship between them, is warranted in believing that the persuader will act in a manner detrimental to the victim’s welfare if the victim fails to assent. It is the improper use of trust or power to deprive a person of free will and substitute instead another’s objective. Usually the fact pattern involves the victim being isolated from receiving advice except from the persuader. Falling within this rule are situations where, for example, a child takes advantage of an infirm parent, a doctor takes advantage of an ill patient, or a lawyer takes advantage of an unknowledgeable client. If there has been undue influence, the contract is voidable by the party who has been unfairly persuaded. Whether the relationship is one of domination and the persuasion is unfair is a factual question. The answer hinges on a host of variables, including “the unfairness of the resulting bargain, the unavailability of independent advice, and the susceptibility of the person persuaded.”Restatement (Second) of Contracts, Section 177(b). See Section 10.5.1 "Undue Influence", Hodge v. Shea.

Key Takeaway

A contract induced by physical duress—threat of bodily harm—is void; a contract induced by improper threats—another type of duress—is voidable. Voidable also are contracts induced by undue influence, where a weak will is overborne by a stronger one.


  1. What are the two types of duress?
  2. What are the elements necessary to support a claim of undue influence?