How are affirmative defenses of duress and necessity treated in U.S. law?

Question

Duress and Necessity are two common law "affirmative defenses" that can be argued for acquittal of a criminal charge.

However I can't find clear law or precedent for either in the United States.

1. Are they viable defenses in practice?
2. Does any jurisprudence provide particular guidelines to their application in criminal law?
3. Is "duress" limited to circumstances of a threat of "imminent harm"? Or are less imminent circumstances of coercion – e.g., extortion, blackmail, or psychological manipulation – viable affirmative defenses under legal doctrine of duress?

Answer 1

Yes, both duress and necessity remain viable defenses.

The contours of these defenses will vary from state to state, but many states use the Model Penal Code.

MPC § 3.02(1) lays out the necessity defense, which it calls justification:

Conduct that the actor believes to be necessary to avoid a harm or evil to himself or to another is justifiable, provided that:

(a) the harm or evil sought to be avoided by such conduct is greater than that sought to be prevented by the law defining the offense charged; and

(b) neither the Code nor other law defining the offense provides exceptions or defenses dealing with the specific situation involved; and

(c) a legislative purpose to exclude the justification claimed does not otherwise plainly appear.

MPC § 2.09(1) lays out the standard for duress:

It is an affirmative defense that the actor engaged in the conduct charged to constitute an offense because he was coerced to do so by the use of, or a threat to use, unlawful force against his person or the person of another, that a person of reasonable firmness in his situation would have been unable to resist.

So MPC § 2.09 does not explicitly make imminence a requirement for the duress defense, but it adopts an objective standard, which permits the jury to factor in that consideration. A "person of reasonable firmness" would be less able to resist robbing a bank if the threat was to kill their child in 30 seconds than if the threat was to kill their grandmother in 50 years, during which the defendant can call the police to investigate the threat and the odds are good that granny dies anyway.

I'd guess most duress cases fall somewhere in the middle, so it becomes a question for the jury whether the threat was serious enough and imminent enough to merit justification.