Many states and the federal courts recognize defenses to criminal charges in limited circumstances when the defendant was under duress or committed the criminal offense out of necessity to avoid death or serious bodily injury. The definitions for these affirmative defenses vary from state to state and in the federal courts, with some jurisdictions treating them as the same defense, and others making the distinction that duress applies when a defendant committed the crime because someone forced them to do it, and necessity applies when the defendant was confronted with bad alternatives in an emergency situation and chose the best alternative.

The elements of the defense of duress or necessity are that (1) the defendant was facing an unlawful and imminent threat sufficient to create a reasonable apprehension of death or serious bodily injury; (2) the defendant had not recklessly or negligently placed himself in a situation where he would likely be forced to commit a criminal act; (3) the defendant had no reasonable, legal alternative to violating the law; and (4) the defendant could have reasonably believed that the commission of the criminal act would avoid the threatened harm.

Duress and necessity defenses to criminal charges may be located in a state’s court opinions or cases (common law) or in its statutes—usually in the penal or criminal code. Many states have pattern or form jury charges (questions and instructions) and include a question that may be given to the jury to determine whether the defendant’s conduct is excused by the defense of duress or necessity.

In Missouri, the defenses of duress and necessity are recognized as potential affirmative defenses to criminal charges under certain circumstances. These defenses can be invoked when a defendant claims that they committed a crime to avoid death or serious bodily injury. The elements required for these defenses typically include an imminent and unlawful threat that would cause a reasonable person to fear death or serious bodily injury, the defendant's lack of contribution to the situation through reckless or negligent behavior, the absence of a reasonable legal alternative to committing the crime, and a belief that the criminal act was necessary to prevent the threatened harm. Missouri law distinguishes between duress and necessity, with duress involving compulsion by another person and necessity involving a choice between limited, bad options in an emergency situation. These defenses are not just derived from Missouri's common law but may also be found in the state's statutes and are considered during jury instructions. It is important for defendants to consult with an attorney to understand how these defenses might apply to their specific case and whether they can be effectively raised in court.