Learning Outcomes
After reading this article, you will be able to distinguish mistake of fact from mistake of law, identify when each may serve as a defense to criminal charges, and apply the correct rules to specific intent, general intent, malice, and strict liability crimes. You will also be able to spot common exam pitfalls and confidently answer MBE questions on this topic.
MBE Syllabus
For the MBE, you are required to understand how mistakes of fact or law affect criminal liability. This includes:
- Recognizing the difference between mistake of fact and mistake of law.
- Knowing when mistake of fact is a defense to specific intent, general intent, malice, and strict liability crimes.
- Understanding the rare circumstances when mistake of law may be a defense.
- Applying these rules to MBE-style criminal law questions.
- Distinguishing between reasonable and unreasonable mistakes.
Test Your Knowledge
Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.
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Which of the following is most likely a defense to a general intent crime?
- A reasonable mistake of fact.
- An unreasonable mistake of fact.
- A mistake of law.
- A reasonable belief that the law did not apply.
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For which type of crime is an unreasonable mistake of fact potentially a defense?
- Strict liability crimes.
- General intent crimes.
- Specific intent crimes.
- Malice crimes.
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Which of the following is generally NOT a defense to criminal liability?
- Mistake of fact that negates the required mental state.
- Mistake of law about whether conduct is criminal.
- Reasonable mistake of fact in a general intent crime.
- Unreasonable mistake of fact in a specific intent crime.
Introduction
Mistake of fact and mistake of law are distinct legal concepts that can affect criminal liability. Understanding when each operates as a defense is essential for MBE success. The rules differ depending on whether the crime requires specific intent, general intent, malice, or is a strict liability offense.
Mistake of Fact
A mistake of fact occurs when a person misunderstands a factual circumstance relevant to the alleged crime. Whether this mistake is a defense depends on the type of crime and whether the mistake is reasonable or unreasonable.
Key Term: Mistake of Fact
A misunderstanding or ignorance about a factual situation relevant to the alleged crime, which may, in some cases, negate the required mental state for liability.
Mistake of Law
A mistake of law arises when a person is unaware that their conduct is criminal or misunderstands the law's meaning. Generally, ignorance of the law is not a defense, but there are rare exceptions.
Key Term: Mistake of Law
A misunderstanding or ignorance about whether conduct is prohibited by law, which is almost never a defense to criminal liability except in narrow circumstances.
Types of Crimes and the Effect of Mistake
The effect of a mistake depends on the mental state required by the crime:
- Specific Intent Crimes: Require proof that the defendant intended a particular result or consequence.
- General Intent Crimes: Require only an intent to do the act, not to achieve a specific result.
- Malice Crimes: Require recklessness or a general awareness of risk.
- Strict Liability Crimes: Require no mental state—mere commission of the act is enough.
Key Term: Specific Intent Crime
A crime that requires the defendant to act with a particular purpose or objective in mind, beyond merely performing the act itself.Key Term: General Intent Crime
A crime that requires only an intent to perform the prohibited act, not to achieve a further result.
Mistake of Fact as a Defense
- Specific Intent Crimes: Any mistake of fact, whether reasonable or unreasonable, is a defense if it negates the specific intent required.
- General Intent and Malice Crimes: Only a reasonable mistake of fact is a defense.
- Strict Liability Crimes: Mistake of fact is never a defense, regardless of reasonableness.
Mistake of Law as a Defense
- Generally, mistake of law is NOT a defense.
- Exceptions:
- If the law was not reasonably made available or published.
- If the defendant reasonably relied on an official statement of law later determined to be incorrect (e.g., from a statute or judicial decision).
- If knowledge of the law is an element of the offense (rare).
Worked Example 1.1
A man picks up a suitcase at an airport, genuinely believing it is his own, but it actually belongs to someone else. He is charged with larceny, a specific intent crime.
Answer:
The man has a defense. Any mistake of fact, even if unreasonable, is a defense to specific intent crimes if it negates the required intent to permanently deprive the owner.
Worked Example 1.2
A woman is charged with battery (a general intent crime) after hitting someone, believing the person was an intruder. In fact, it was her neighbor, who had permission to enter.
Answer:
The woman has a defense only if her mistake was reasonable. For general intent crimes, only a reasonable mistake of fact is a defense.
Worked Example 1.3
A defendant is charged with selling alcohol to a minor, a strict liability offense. He reasonably believed the buyer was over 21 based on a fake ID.
Answer:
No defense. For strict liability crimes, mistake of fact is never a defense, even if reasonable.
Exam Warning
On the MBE, do not confuse mistake of fact with mistake of law. Only mistake of fact can be a defense to most crimes, and only in the circumstances outlined above. Mistake of law is almost never a defense.
Revision Tip
For specific intent crimes, always consider whether any mistake—reasonable or not—could negate the required intent. For general intent or malice crimes, check if the mistake was reasonable.
Key Point Checklist
This article has covered the following key knowledge points:
- Mistake of fact may be a defense to criminal liability, depending on the type of crime and whether the mistake is reasonable.
- For specific intent crimes, any mistake of fact (reasonable or not) is a defense if it negates intent.
- For general intent or malice crimes, only a reasonable mistake of fact is a defense.
- For strict liability crimes, mistake of fact is never a defense.
- Mistake of law is almost never a defense, except in rare, narrow circumstances.
- Always distinguish between mistake of fact and mistake of law on the MBE.
Key Terms and Concepts
- Mistake of Fact
- Mistake of Law
- Specific Intent Crime
- General Intent Crime
