Introduction
Sunday completes the Criminal Law Fall Launch by turning from the definition of offenses to the doctrines that may defeat, justify, excuse, mitigate, or otherwise alter criminal liability.
The order of analysis matters. Students should begin every defense problem by separating arguments into three distinct categories:
Failure of Proof
The prosecution simply failed to establish an element (e.g., no required mens rea, no legally sufficient act, no causation).
Justification
The conduct occurred satisfying the offense, but it was legally permissible under the circumstances (e.g., self-defense, necessity).
Excuse
The conduct was wrongful, but the specific defendant should not be held fully criminally responsible (e.g., duress, insanity, infancy).
This classification prevents students from treating every defensive argument as though it means “D did nothing wrong.” Self-defense does not mean D failed to intend the act. Duress does not mean the forced conduct became socially desirable.
1. What offense has the prosecution established?
2. What doctrine, if any, changes the defendant’s liability?
I Self-Defense
Self-defense is a justification. A person may use reasonable force when reasonably believing that force is necessary to protect against imminent unlawful force.
A complete analysis should ask:
- Was the threatened force unlawful?
- Was the threat imminent?
- Did D actually believe defensive force was necessary?
- Was that belief reasonable?
- Was the amount of force proportional?
- Was D the initial aggressor?
- Was retreat required under the governing law?
Imminence vs. Retaliation
Self-defense is designed to prevent threatened harm, not to authorize retaliation for harm that has already ended. If V attacks D, stops, and leaves, D cannot follow V twenty minutes later and attack V in revenge. Retaliation after the danger has ended is not ordinary self-defense.
Reasonableness & Imperfect Self-Defense
D must actually believe defensive force is necessary (subjective), and that belief must be reasonable (objective). An honest but unreasonable belief fails complete self-defense. However, in jurisdictions recognizing imperfect self-defense, that unreasonable belief may mitigate murder to voluntary manslaughter.
Proportionality: Nondeadly vs. Deadly Force
Reasonable nondeadly force may be used to prevent unlawful force. D need not wait for the first punch to land. Deadly force generally requires a reasonable belief in an imminent threat of death, serious bodily injury, or a qualifying violent felony. Shooting someone who threatens a minor slap is disproportionate.
Retreat & Initial Aggressor Rules
Jurisdictions differ over retreat. Some require safe retreat before using deadly force (with exceptions like the home), while others use "stand-your-ground" rules. An initial aggressor loses the right to self-defense unless they communicate withdrawal or the victim escalates a nondeadly confrontation into disproportionate deadly force.
Common Trap
Do not write that “there is never a duty to retreat” or “D must always retreat.” Apply the specific rule stated in the jurisdiction provided by the problem.
II. Defense of Others & Property
Defense of Others
Modern Approach
Asks whether the defender reasonably believed the third person had a right to use self-defense. Protects a reasonable misunderstanding.
Alter-Ego Approach
The defender stands in the shoes of the third person. Defense fails if the third person was actually the aggressor, regardless of D's reasonable belief.
Defense of Property
Reasonable nondeadly force may generally be used to protect property. Deadly force ordinarily cannot be used solely to protect property.
However, if an intruder violently enters an occupied home, the problem is no longer solely about property. Defense of persons becomes central, which can materially change the permitted level of force.
III Necessity vs. Duress
Necessity (Justification)
Pressure from circumstances (the lesser evil).
- Imminent threat of significant harm.
- Reasonable belief criminal act is necessary.
- No adequate lawful alternative.
- Harm avoided is greater than harm caused.
- D did not substantially create emergency.
Example: Breaking into a cabin to escape a deadly blizzard.
Duress (Excuse)
Pressure from another person (coercion).
- Threat of death or serious bodily harm.
- Sufficiently imminent threat.
- Reasonable fear threat will be carried out.
- No reasonable opportunity to escape.
- D not at fault in creating situation.
Example: Driving a getaway car because a criminal holds a gun to D's head.
Traditional common law generally did not permit necessity or duress as a defense to intentional homicide, though modern statutes may vary.
IV Mistake of Fact & Law
Mistake of fact is a failure-of-proof doctrine. The question is: Did D's factual mistake prevent D from possessing the mens rea required by the offense?
- Specific Intent: An honest mistake traditionally may negate the required intent even if the mistake is unreasonable.
- General Intent: The mistake ordinarily must be both honest AND reasonable.
- Strict Liability: Mistake generally does not negate a strict-liability element.
Mistake of Law
The general rule: Ignorance of criminal law is no excuse. A person usually cannot avoid conviction merely by saying, "I didn't know it was illegal."
Exceptions may arise through: Official reliance on an authoritative interpretation, unavailable/unpublished law, a statute that specifically has a knowledge-of-law element, or a mistake concerning collateral law (like property ownership) that negates the mens rea of theft.
V. Intoxication
Voluntary intoxication traditionally may negate a specific-intent element if intoxication actually prevents formation of that intent (e.g., premeditation, larcenous intent). It is generally NOT a defense to general-intent crimes, malice, recklessness, negligence, or strict liability.
Under MPC principles, a voluntarily intoxicated person may still be treated as reckless regarding risks they would have perceived while sober.
Involuntary intoxication (coerced, unexpected medication reaction, unknowing ingestion) may provide a broader excuse if it creates a mental condition comparable to legal insanity.
Exam Tip
Voluntary intoxication is not a general excuse. Ask: What specific mental-state element does D claim the intoxication prevented?
VI Insanity & Infancy
Insanity concerns criminal responsibility at the time of the offense (unlike competency, which concerns present ability to stand trial).
M'Naghten Test (Cognitive)
Because of mental disease/defect, D did not know the nature and quality of the act, OR did not know the act was wrong.
Irresistible Impulse (Volitional)
Mental disease prevented the ability to control conduct, even if D understood its wrongfulness.
MPC Test
D lacked substantial capacity either to appreciate criminality/wrongfulness OR to conform conduct to law.
Durham Test
The unlawful act was the "product" of mental disease or defect. (Rarely used today).
Infancy: Common law used age-based presumptions (young children conclusively presumed incapable; older children rebuttably presumed incapable). Modern juvenile codes largely replace these rules.
VII. Entrapment
Limits law-enforcement inducement of crime.
- Subjective Approach: Focuses on whether the government induced the offense AND whether D was predisposed to commit it. Merely providing an opportunity is not enough; strong pressure or exploitation is required.
- Objective Approach: Focuses on whether police methods would induce an ordinarily law-abiding person to commit the offense, regardless of D's personal predisposition.
VIII. Complete 12-Step Exam Framework
1. Identify every potential offense.
2. State the elements.
3. Analyze actus reus.
4. Analyze mens rea.
5. Analyze concurrence.
6. Analyze causation.
7. Grade the offense.
8. Analyze inchoate liability.
9. Analyze liability for others.
10. Analyze defenses.
11. Address merger/lesser-included.
12. Reach a reasoned conclusion.
IX. Common Exam Traps
- Treating motive as mens rea.
- Punishing an omission without a legal duty.
- Assuming statutory silence means strict liability.
- Calling every intentional killing 1st-degree murder.
- Using felony murder without checking merger.
- Skipping causation in homicide.
- Confusing Larceny, Embezzlement, and False Pretenses.
- Forgetting Robbery requires force/threat.
- Assuming Conspiracy merges.
- Confusing Insanity (past) and Competency (present).
X. Sunday Capstone Hypo
"D drinks heavily, then enters a jewelry store after hours with Friend, intending to steal. Driver waits outside for $1,000. Inside, D strikes a Security Guard with a crowbar, thinking the Guard was drawing a weapon. Friend takes the diamonds. During escape, Driver runs a red light and kills Pedestrian. Later, Guard dies from a hospital medication error. Friend hides the diamonds at Relative's house, who agrees to help after hearing the story."
Analysis Must Be Actor-by-Actor:
- D: Solicitation, Conspiracy, Burglary, Robbery. Self-defense claim fails if D is an initial aggressor intruding unlawfully. Hospital error is ordinary negligence (does not break causation for felony murder). Intoxication defense fails because D formed the specific intent to steal prior to entry.
- Friend: Co-conspirator and accomplice. Friend physically committed Larceny, which escalates to Robbery due to D's force. Liable for felony murder of Guard and Pedestrian.
- Driver: Liability is limited by knowledge. Driver knew of theft, not violence. This affects accomplice and conspiracy scope. Felony murder still applies for Pedestrian death during immediate flight.
- Relative: No prior knowledge. Cannot be an accomplice to the original crimes. Faces post-crime liability: Accessory After the Fact and Receiving Stolen Property.
Chapter Summary
Defenses must be classified as Failure of Proof (prosecution missing an element), Justification (conduct was legally permissible), or Excuse (conduct was wrongful but actor is not responsible).
Self-Defense is a justification requiring a reasonable belief in imminent unlawful force. Deadly force requires a threat of death/serious injury. Initial aggressors lose the right unless they withdraw. Defense of property allows nondeadly force, but never deadly force solely for property.
Necessity justifies crimes committed to prevent a greater harm (pressure from circumstances). Duress excuses crimes committed under threat of imminent death/serious harm from another person.
Mistake of Fact negates mens rea. Honest mistake suffices for specific intent; must be honest AND reasonable for general intent. Mistake of Law is generally no excuse.
Voluntary Intoxication can negate specific intent if it actually prevented its formation. Insanity tests include M'Naghten (cognitive), Irresistible Impulse (volitional), and MPC (substantial capacity).
Entrapment relies on subjective (government inducement + lack of predisposition) or objective (police methods) tests depending on jurisdiction.
The 12-step method demands analyzing every crime, element, and defense actor by actor. Postcrime assistance (Relative) is Accessory After the Fact, not Accomplice liability.