Also known as: MPC § 2.04 · Model Penal Code section 2.04 · MPC 2.04 · ignorance or mistake
Written by attorneys · grounded in primary & secondary sources — see below
A statutory provision establishing when ignorance or mistake as to fact or law supplies a defense to criminal liability. The defense is available if the error negatives the culpable mental state required for a material element of the offense or if the governing law treats the resulting state of mind as exculpatory. The defense is also available when the actor reasonably relies on an official but erroneous statement of law. When the defendant would still be guilty of a lesser offense under the facts as supposed, the provision reduces the grade and degree of the conviction rather than barring liability entirely.
Select any source to read its text and confirm it supports the definition.
Michelle Murphy, a software engineer, reviewed her company's data policy and formed the sincere belief that a customer data set had already been anonymized. She integrated the data into an algorithm and launched it, unaware that visible personal identifiers remained. The mistake prevented her from possessing the knowledge that the information was still identifiable at the time of use.
Marcus Mitchell, a nurse practitioner, received direct assurance from the supervising physician that a medication had been reclassified as over-the-counter. He administered it from clinic stock without a prescription, relying on that statement. The resulting state of mind aligned with the exculpatory mental state recognized by the governing law.
Mohan Malhotra attended an agency seminar where an agency lawyer stated that certain conduct fell outside domestic regulatory rules. He engaged in the conduct just beyond the stated line in reliance on the statement. The reasonable reliance on the official yet erroneous interpretation supplied the exculpatory state of mind.
Melanie Morris received confirmation at a company compliance seminar that a civilian drone design was exempt from export restrictions. She emailed the design files abroad believing the material was uncontrolled. The honest mistake undercut the knowledge element the prosecution was required to prove.
Miguel Mendoza saw copper pipes on a neighboring vacant lot and recalled an old email indicating the materials had been abandoned with permission. He directed workers to remove the pipes believing they were discarded scrap. The genuine belief negated the intent to take property belonging to another.
The defense applies when the defendant's ignorance or mistake prevents formation of the purpose, knowledge, belief, recklessness, or negligence that the offense requires for a material element. Courts examine whether the error directly undercuts the culpable mental state the prosecution must prove beyond a reasonable doubt.
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…classes: [¶] .... .... .... .... .... .... .... [¶] Three — Persons who committed the act or made the omission charged under an ignorance or mistake of fact, which disproves any criminal intent." [^maj-5]: Since Mayberry , supra , the Courts of Appeal have struggled with the issue of when an instruction on reasonable and good faith…
…relies upon section 26 of that code
…who is charged by law with the responsibility for the interpretation or enforcement of the law defining the offense. See Model Penal Code § 2.04
…The proposition that New York adopted the MPC general approach finds additional support in the comments to section
…to the offense. The Model Penal
Yes, when the governing law itself treats the state of mind produced by the ignorance or mistake as a defense. This independent basis operates separately from negation of a material element.
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The defense is unavailable to bar conviction entirely, but the ignorance or mistake reduces the grade and degree of the offense to those of the lesser crime the defendant would have committed.
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Yes, when the defendant acts in reasonable reliance on an official statement contained in a statute, judicial decision, administrative order, or interpretation by the public officer charged with enforcement of the law, and the statement is later determined to be invalid.
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Yes, when the statute or other enactment defining the offense was not known to the actor and had not been published or otherwise reasonably made available prior to the conduct.
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