coercion, in law, the unlawful act of compelling a person to do, or to abstain from doing, something by depriving him of the exercise of his free will, particularly by use or threat of physical or moral force. In many states of the United States, statutes declare a person guilty of a misdemeanor if he, by violence or injury to another's person, family, or property, or by depriving him of his clothing or any tool or implement, or by intimidating him with threat of force, compels that other to perform some act that the other is not legally bound to perform. Coercion may involve other crimes, such as assault. In the law of contracts, the use of unfair persuasion to procure an agreement is known as duress; such a contract is void unless later ratified. At common law, one who commits a crime under coercion may be excused if he can show that the danger of death or great bodily harm was present and imminent. However, coercion is not a defense for the murder or attempted murder of an innocent third party.