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    Colorado Criminal Law Defenses – The Defense of Mistakes of Law and Mistake of Fact


    Introduction – This web page addresses certain legally recognized defenses in Colorado – The Defenses of Mistake of Fact and Mistake of Law.


    The Main Categories of Defenses

    The Justification Defenses

    A justification defense deems conduct that is otherwise criminal to be socially acceptable and non-punishable under the specific circumstances of the case. Justification focuses on the nature of the conduct under the circumstances.

    Examples include:

    • Self-defense

    • Defense of others

    • Defense of property and habitation

    • Use of lawful force

    • Necessity

    The Excuse Defenses

    Excuse defenses focus on the defendant’s moral culpability or his ability to possess the requisite mens rea ( mental state). An excuse defense recognizes that the defendant has caused some social harm but that he should not be blamed or punished for such harm.

    Examples include:

    • Duress

    • Insanity

    • Diminished capacity

    • Intoxication (in very limited circumstances)

    Mistake of fact

    • Mistake of law (in very limited circumstances)

    The Mistake of Fact Defense

    The Common Law Rules

    The  General Approach – Many states follow the Model Penal Code in requiring proof of the crimes requirement of the mental state -(mens rea) for every element of the offense.

    Nevertheless, the common law’s two approaches to mistakes—depending on whether the offense charged is characterized as general-intent or specific-intent—has endured.

    If the crime is one of strict liability, ( that is – there is no requirement of a mental state) then the defense of  a mistake of fact is irrelevant.

    Otherwise, the first step in analyzing a mistake-of-fact claim in a jurisdiction that follows common law doctrine is to determine whether the nature of the crime of which the defendant has been charge is specific intent  or general-intent.

    The Specific-Intent Offenses

    A defendant is not guilty of an offense if his mistake of fact negates the specific-intent portion of the crime, i.e., if he lacks the intent designated in the definition of the offense, e.g., “knowingly,” “negligently,” “recklessly.”

    The General-Intent Offenses

    Ordinary Approach: Reasonableness

    – The ordinary rule is that a person is not guilty of a general-intent crime if his mistake of fact was reasonable, but he is guilty if his mistake was unreasonable.

    The Moral-Wrong Doctrine

    – On occasion, courts apply the “moral wrong” doctrine, under which one can make a reasonable mistake regarding an attendant circumstance and yet manifest a bad character or otherwise demonstrate worthiness of punishment. The rule is generally that there is no exculpation for mistakes where, if the facts had been as the defendant believed them to be, his conduct would still be immoral.

    The Legal-Wrong Doctrine

    – A less extreme alternative to the moral-wrong doctrine is the “legal-wrong doctrine.” That rule provides for no exculpation for mistakes where, if the facts were as the defendant thought them to be, his conduct would still be “illegal.” Often this means that a defendant possessed the mens rea for committing a lesser offense, but the criminal act (actus reus) was associated with a higher offense. Under this doctrine, the defendant is guilty of the higher offense in such circumstances.

    The Model Penal Code

    The  General Rule – Section 2.04(1) provides that a mistake is a defense if it negates the mental state required to establish any element of the offense.

    The Exception to the Rule

    The defense of mistake-of-fact is not available if the defendant would be guilty of another offense, had the circumstances been as he supposed. In such cases, contrary to the common law, the Code only permits punishment at the level of the lesser offense. [MPC § 2.04(2)]

    The Mistakes of Law Defense  – The General Principle

    Under both the common law and Model Penal Code, ignorance of the law excuses no one. Nevertheless, a number of doctrines apply when a defendant is ignorant or mistaken about the law.

    The Reasonable-Reliance Doctrine (Entrapment by Estoppel)

    Under both the common law and Model Penal Code, a person is excused for committing a criminal offense if he reasonably relies on an official statement of the law, later determined to be erroneous, obtained from a person or public body with responsibility for the interpretation, administration, or enforcement of the law defining the offense.

    “Official Statement”

    For a statement of the law to be “official,” it must be contained in:

    (1) a statute later declared to be invalid;

    (2) a judicial decision of the highest court in the jurisdiction, later determined to be erroneous;


    (3) an official, but erroneous, interpretation of the law, secured from a public officer in charge of its interpretation, administration, or enforcement, such as the Attorney General of the state or, in the case of federal law, of the United States.

    Even if a person obtains an interpretation of the law from a proper source, that interpretation must come in an “official” manner, not an offhand or informal manner. For example, a person may rely on an official “opinion letter” from the state Attorney General, formally interpreting the statute in question.

    Exemptions to the Reasonable Reliance Doctrine

    Reliance on One’s Own Interpretation of the Law – A person is not excused for committing a crime if he relies on his own erroneous reading of the law, even if a reasonable person – even a reasonable law–trained person – would have similarly misunderstood the law.

    Advice of Prosecutor – Although there is very little case law on the matter, there is some support for the proposition that a person may not reasonably rely on an interpretation ofa law provided by a local prosecuting attorney.

    Advice of Private Counsel – Reliance on erroneous advice provided by a private attorney is not a defense to a crime.

    Fair Notice and the Lambert Principle

    Common Law – At common law, every one is presumed to know the law. However, in Lambert v. California [355 U.S. 225 (1957)], the Court overturned the petitioner’s conviction for failing to register with the city of Los Angeles as a prior convicted felon, as required pursuant to a strict liability ordinance of which he was unaware; the Court reversed on “lack of fair notice” due process grounds.

    The Supreme Court held in Lambert that, under very limited circumstances, a person who isunaware of a duly enacted and published criminal statute may successfully assert a constitutional defense in a prosecution of that offense.

    Key to the court’s decision in Lambert was the passive nature of the offense. Namely, (1) it punished an omission (failure to register); (2) the duty to act was imposed on the basis of a status (presence in Los Angeles), rather than on the basis of an activity; and (3) the offense was malum prohibitum. As a result of these factors, there was nothing to alert a reasonable person to the need to inquire into the law.

    The Model Code – The Model Penal Code’s fair notice exception [MPC § 2.04(3)(a)] applies where:

    (1) a defendant does not believe that his conduct is illegal, and

    (2) the statute defining the offense is not known to him; and was “not published or otherwise reasonably made available” to him before he violated the law.

    Ignorance or Mistake that Negates Mens Rea

    Common Law

    “Different Law” Approach – A defendant’s lack of knowledge of, or misunderstanding regarding the meaning or application of, another law – usually, it will be a nonpenal law – will negate the mens rea element in the definition of the criminal offense.

    When a defendant seeks to avoid conviction for a criminal offense by asserting a different law mistake, on the ground that the different-law mistake negates his mens rea, the first matter for determination is whether the offense charged is one of specific-intent, generalintent, or strict-liability.

    Specific-Intent Offenses – A different-law mistake, whether reasonable or unreasonable, is a defense in the prosecution of a specific-intent offense, if the mistake negates the specific intent in the prosecuted offense.

    General-Intent Offenses – Although there is very little case law on point, a differentlaw mistake, whether reasonable or unreasonable, apparently is not a defense to a general intent crime.

    Strict-Liability Offenses – A different-law mistake is never a defense to a strict liability offense.

    The Model Penal Code – MPC § 2.04(1) provides that mistake or ignorance of the law is a defense if it negates a material element of the offense. Application of this defense generally surfaces in cases of a different-law mistake.

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    H. Michael Steinberg Esq.
    Attorney and Counselor at Law
    The Colorado Criminal Defense Law Firm of H. Michael Steinberg
    A Denver, Colorado Lawyer Focused Exclusively On
    Colorado Criminal Law For Over 40 Years.
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