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 New York, the defenses of duress and necessity are recognized as potential affirmative defenses to criminal charges under limited circumstances. Duress occurs when a person commits a crime because they were coerced by an immediate threat of death or serious bodily injury, which could not be avoided by any other reasonable means. Necessity, on the other hand, applies when a person is faced with an emergency situation that forces them to choose between violating the law and avoiding a greater harm. New York law requires that for these defenses to be applicable, the threat must be imminent and real, the defendant must not have put themselves in the situation through reckless or negligent behavior, there must be no reasonable legal alternative to committing the crime, and the defendant must reasonably believe that committing the crime was necessary to prevent the threatened harm. These defenses are not just derived from common law but are also codified in New York's Penal Law. Specifically, the necessity defense is codified under NY Penal Law § 35.05, while duress is addressed under NY Penal Law § 40.00. Additionally, New York courts provide pattern jury instructions that help jurors determine if a defendant's actions can be excused by duress or necessity.