Mistake as a Statutory Defense

Mistake as a Statutory Defense

Section 2.04(1) of the Model Penal Code gives a defendant who acted under ignorance or mistake, whether of fact or of law, two separate routes to a defense. Route (a), the subject of the preceding sections, asks whether the mistake negatives the purpose, knowledge, belief, recklessness, or negligence required to establish a material element of the offense.¹ Route (b) asks a different question, which is whether "the law provides that the state of mind established by such ignorance or mistake constitutes a defense."² Route (a) works from inside the offense, because the mistake defeats an element the prosecution must prove. Route (b) works from outside it, because some provision of law, whether in the definition of the offense or in a separate defense, declares that a particular belief excuses. A defendant who loses under route (a) therefore has one more question to answer before the mistake claim is finished, namely whether the law has attached a defense to the belief.

The second route exists because the first has a blind spot. Route (a) can help only when the offense requires culpability as to the element the defendant misjudged, since a mistake works by showing that the required mental state was absent. If the element carries no culpability requirement, the offense is strict as to that element, and a mistake about it negates nothing because there is nothing for it to negate. A statute forbidding the sale of alcohol to a minor shows the pattern. Most courts require proof that the seller knew he was selling liquor, so a seller who thought the bottle held water is excused, but the customer's age is the element on which the offense is strict.³ A bartender who reasonably relies on a license and a union card showing the customer to be 24 is therefore guilty if the customer is really 17, and even a bartender who demands every conceivable document remains liable when everyone, including the customer's parents, is honestly wrong about a birth date.⁴ In that setting the defendant's belief about age is simply not something the offense asks about, and only a rule that speaks to the belief directly can give it any weight.

Strictness as to an element is a conclusion the law must support, because courts do not infer from legislative silence that a mental element has been dropped. In Morissette v. United States the defendant took spent bomb casings from a former bombing range, sold them as scrap, and said he believed they had been abandoned; the Court read the statute's reference to knowingly converting government property against the common-law background of larceny-type offenses and found that it required criminal intent, because eliminating intent from a criminal statute must be clearly expressed.⁵ Its earlier strict-liability decisions involved regulation of dangerous or harmful items, which explains why a statute defining a common-law style offense receives no such treatment by implication. The Code handles absolute liability in its own provision, section 2.05, which addresses violations and offenses defined by statutes outside the Code and lies outside the scope of this chapter.⁶

Where an element is strict, route (b) lets a legislature decide that a belief should excuse anyway, and it lets the legislature write the terms of the excuse. A statute may state a mistake-of-fact defense and set its own standard, so the quality of belief required can vary from one offense to the next.⁷ One provision might demand only an honest belief, while another demands belief on reasonable grounds. Leaving the choice to individual offenses avoids a single rule that would either excuse too much, if every honest belief excused every strict element, or too little, if no belief ever did. A legislature that makes an element strict puts the risk of error on the actor who is best placed to check, and a reasonable-belief defense then softens that allocation for the actor who did check.

In the box, the first defendant is acquitted although the belief about age negated no mental state, because the law itself made reasonable belief a defense. The second defendant's belief was equally sincere, yet it fails, since the provision that creates the defense requires reasonable grounds and route (a) offers nothing on an element that carries no culpability. The single fact that moved the answer is the reasonableness of the belief, and it matters only because the defense provision made it matter. Students lose this issue when they treat a reasonable mistake about a strict-liability element as a defense without first locating the provision that makes it one.⁸

Route (b) is also unavailable whenever the law supplies no defense, and for some offenses the Code supplies none at all. Where criminality depends on the child's being under ten, the Code's treatment of sex offenses makes it no defense that the actor believed the child to be older.⁹ The reason is that no credible error about the age of a child who is in fact under ten would make the conduct anything less than a dramatic departure from societal norms, so a mistake defense would protect no one who deserves protection.¹⁰ The actor in the box and the actor in this offense are wrong about the same fact, yet one may be excused and the other cannot be, because the law attached a defense to the belief in one offense and withheld it in the other. The Code treats such judgments as matters of policy to be made offense by offense.¹¹ The same drafting choice appears outside criminal law, and civil securities regulation is offered here only as an analogy and not as criminal authority. In drafting section 18 of the Securities Exchange Act of 1934, an early version protected a defendant who acted in good faith and with reasonable care, the accounting profession objected that it would impose liability for honest errors in judgment, and the enacted version protects a defendant who acted in good faith and had no knowledge that the statement was false or misleading, as described in Ernst & Ernst v. Hochfelder.¹²