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 Arizona, the defenses of duress and necessity are recognized under certain circumstances in criminal cases. These affirmative defenses can be invoked when a defendant claims they committed a crime to avoid death or serious bodily injury. The defense of duress applies when the defendant was compelled to commit the crime due to force or threat by another person, while the defense of necessity is applicable when the defendant was faced with an emergency situation and chose the least harmful option among bad alternatives. The key elements required for these defenses include an unlawful and imminent threat that would cause a reasonable person to fear death or serious bodily injury, the defendant not having placed themselves in the situation through recklessness or negligence, no reasonable legal alternative to committing the crime, and a reasonable belief that the crime would prevent the threatened harm. These defenses are derived from both Arizona's statutory law, found in the Arizona Revised Statutes, and case law established by court opinions. Additionally, Arizona courts may provide jury instructions that include questions to help determine if a defendant's actions are excusable under duress or necessity.