If a person is forced into entering a contract on threat of physical bodily harm, he or she is the victim of physical duress. 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.