Concept

Mistake and Imperfect Self-Defense

Self-defense and justifiable homicide

Mistake and Imperfect Self-Defense

Every requirement taught so far has assumed that the defender read the situation correctly: the force really was unlawful, the threat really was deadly, and the exit really was unsafe. Real confrontations seldom offer that certainty, so the last question in this chapter is what the law does with a defender who turns out to have been wrong. The answer depends on the quality of the error. A reasonable mistake leaves the defense intact, which means that a killing that proves to have been unnecessary can still end in acquittal. An unreasonable mistake generally destroys the perfect defense, and some jurisdictions then ask whether the defender's blame falls closer to manslaughter than to murder. Those two outcomes sit at opposite ends of the justified, excused, and criminal classification that opened this chapter, and the sections below follow the defender's error from the first to the second.

Reasonable Mistake

When the defender's belief on any of these points was reasonable, every court allows the claim of self-defense.² The fourth kind matters only where a retreat duty exists, and it shows the logic common to all four. The retreat rule rests on the idea that killing is unnecessary when the defender can avoid the danger by running away.³ A defender who reasonably but wrongly believes that running is unsafe therefore holds a reasonable belief that the killing is necessary, and is protected.⁴ The same reasoning carries over to the other three kinds of mistake, since in each the defender acts on appearances that would have led a careful person to the same conclusion.

Reasonableness is the standard because it sorts defenders who are wrong into two groups that deserve different treatment. A person facing an apparent attacker has seconds to act and rarely has any means of confirming what the other person holds or intends. A rule that demanded accuracy would punish defenders for facts that nobody in their position could have known, and it would make the defense so risky that a defender might hold back until the danger became real, which is often the moment when it is too late to act. A rule that accepted any honest belief would err in the other direction, because it would let the careless and the fearful kill on the strength of their own suspicions. The reasonableness requirement protects the first group completely and withholds protection from the second, who were careless about the facts. Where the law softens the consequences for that second group, it does so through imperfect self-defense, taken up below.

Full protection for a reasonable mistake complicates the classification of homicide taught at the start of this chapter. The killing was in fact unnecessary, because the supposed attacker posed no deadly threat, and that feature resembles an excused killing, in which the actor is forgiven although the act was not authorized. Yet the defender receives the same complete acquittal that a defender who read the facts correctly receives, because the inquiry asks how the situation appeared to a reasonable person on the scene. So a reasonable mistake blurs justification into excuse, and the practical result is the same under either label: the claim of self-defense succeeds and no homicide liability follows.

The rule is easiest to see in a mugging in which the weapon never existed. A stranger confronts a pedestrian, demands money on pain of death, and points what looks like a gun but is really a finger poking through a jacket. The pedestrian has reason to believe that a victim can be shot even after handing over the property, because that has happened in the neighborhood several times recently, and so draws a gun and kills the stranger.⁵ Later evidence shows that the stranger, a career mugger, would never have thought of physically harming a victim. The pedestrian was mistaken twice, about whether a gun existed and about whether it would be used, but both mistakes were reasonable, so the claim of self-defense stands.⁶

Most states treat an unreasonable mistake the opposite way, and the defender loses the claim.⁷ A rider on a New York City subway who carried an unlicensed loaded pistol illustrates the pattern. When four youths approached and one asked for five dollars, the rider shot all four, including one sitting on a bench who apparently posed no imminent threat. The rider later admitted not believing that the youths had a gun and pointed only to a fear, drawn from earlier muggings, of being maimed in the encounter.⁸ A fear built from past experience describes the rider's history and says little about what this encounter showed, so it reads as the kind of belief that fails the reasonableness standard.

Students lose this issue when they let hindsight decide it. The mugger in the earlier example was harmless, and the proof came only afterward, yet the defense held because the inquiry is confined to what a reasonable person could perceive at the moment of the act.⁹

Exam Analysis Steps

Because the effect of an error depends on whether the belief was reasonable, a claimed mistake is best handled by locating the belief first and grading it second. The steps are these:

Identify which belief was wrong: whether an attack was coming, whether the force was unlawful, whether deadly force was needed, or whether retreat was safe.
Confirm that the defender actually held that belief at the time of the act.
Ask whether a reasonable person in the defender's position would have held the belief, relying only on what the defender could perceive then.
If the belief was reasonable, evaluate the defense as though the facts were as the defender believed them, and if it was unreasonable, treat the perfect defense as lost and ask whether the jurisdiction recognizes imperfect self-defense.

Imperfect Self-Defense

Once a mistake is unreasonable, the perfect defense is gone in most states, and the killing falls into the residual category of criminal homicide described at the start of this chapter. Imperfect self-defense determines how serious a crime that killing is. It applies only when the person claiming self-defense has killed the attacker and cannot succeed with a perfect defense, and its function is to reduce what would otherwise be murder to voluntary manslaughter.¹¹ The mechanism is the one that operates in provocation: both doctrines assume that the killing was unlawful, but a mitigating circumstance means that it lacked malice aforethought, the mental state that separates murder from manslaughter.¹² At common law self-defense was all or nothing, so a jury that found a sincere but unjustified fear had to choose between acquittal and a murder conviction, and imperfect self-defense gives that jury a verdict that matches the defender's actual blame.¹³

The doctrine is a fallback, so it never competes with a successful perfect defense. A defender who proves perfect self-defense is acquitted and has nothing left to reduce, while a defender who killed with no genuine fear and no justification receives no mitigation at all. Two situations earn the reduction in jurisdictions that recognize it, and each is taken up separately below because each rests on a different reason that the killing lacked malice.

Aggressor Forced to Kill

The first situation involves a person who started the confrontation without committing a felony and is then forced to kill. Where one person punches another in the nose and the victim retaliates by trying to kill the puncher with a knife, the puncher who kills in response has no perfect self-defense in jurisdictions that deny the defense to an aggressor, because the original battery precipitated the altercation.¹⁵ The puncher is guilty of manslaughter rather than murder, as North Carolina's decision in State v. Norris reflects.¹⁶ The reduction rests on the mental state behind the original wrong. A punch is not an attempt to kill, so an aggressor who later kills to save a life that is really in danger acts in response to a deadly threat that the aggressor provoked without intending it, and the killing, though unlawful, lacks the malice that murder requires. Jurisdictions that restore the full defense to a non-deadly aggressor who meets unexpected deadly force, as the earlier discussion of the initial aggressor describes, have less need for imperfect self-defense on these facts, because the escalation itself restores the perfect defense.

The Model Penal Code reaches a different answer on the punch-and-knife facts. It would allow the puncher to raise a perfect self-defense, although the puncher remains guilty of the original battery.¹⁷ The difference follows from the Code's aggressor limit, which reaches only an actor who provoked the encounter with the purpose of causing death or serious bodily harm, as the earlier discussion of the initial aggressor explains. A bare battery does not meet that description, so the aggressor limit never forecloses the defense in the first place.

Students overextend this rule when they apply it to a deadly first attack, because the reduction is unavailable when the original attack is felonious. An assailant who attacks a victim with a knife, is repelled, and then shoots the victim as the victim turns to kill the assailant is guilty of murder, not manslaughter, as in Commonwealth v. Blackman.¹⁸ A person who starts a deadly attack has created the lethal danger from which the later killing flows, and nothing in that sequence suggests that the resulting killing lacked malice. The punch and the knife attack therefore differ in a single respect, the seriousness of the first wrong, and that difference separates manslaughter from murder.

Either kind of aggressor can sometimes regain the right of perfect self-defense by total withdrawal from the confrontation, which requires more than a strategic retreat and must be communicated so that the other party can perceive it.¹⁹ The victim is not alive to say whether any withdrawal was communicated, so juries sometimes reject the claim, and the defendant in State v. Mayberry, who raised it, was convicted on retrial.²⁰

Honest but Unreasonable Belief

The second situation involves no aggressor at all. The defender honestly but unreasonably believes that deadly force is necessary to prevent death or grievous bodily harm, as in Shuck v. State.²² Each half of that description does its own work. The unreasonableness of the belief fails the objective standard taught in the first part of this section, so in most jurisdictions the killing is unlawful and the perfect defense is lost, while the honesty of the belief means the defender lacked the malice that murder requires.²³ The result is manslaughter, a verdict that fits a defender who genuinely feared death and misjudged the danger.

Recognition of the doctrine is uneven. Some jurisdictions do not recognize imperfect self-defense for this kind of belief and treat the same killing as murder, as in People v. Manzo.²⁴ The reduction therefore depends on the jurisdiction, and an answer that treats manslaughter as the automatic consequence of an unreasonable belief overstates the law.

The Model Penal Code reaches a related result without using the label. It makes the degree of guilt depend on the defender's culpability as to each element, so a defender who honestly but unreasonably, which is to say negligently, believes that killing is necessary can be convicted of negligent homicide under § 3.09(2).²⁵ The Code measures blame by the mental state the defender actually had about the justifying facts, which places an honest but careless belief in the category of negligence and lets the grade of the offense follow from that mental state.

Reasonable Mistake

Exam Analysis Steps

Self-defense depends on what the defender believed when the force was used, and a belief formed in seconds is sometimes wrong. The usual rule asks whether the belief was honest and also objectively reasonable in light of the surrounding circumstances, so an error that a careful person in the defender's position would also have made leaves the defense intact.²⁷ The Model Penal Code builds its test around belief as well, allowing a person who uses protective force to estimate the necessity of that force under the circumstances as the person believes them to be when the force is used.²⁸ Because the defense rests on the defender's belief, the first step in any mistake problem is to find which belief proved wrong, and the error can occur in any of four places:

The defender believes an attack is about to occur when none was coming.
The defender believes the force being used against the defender is unlawful when it was lawful.
The defender believes that only deadly force will repel the threat when lesser force would have sufficed.
The defender believes that retreat cannot be accomplished safely when it could have been.

The same test governs all four. When the mistaken belief on any of these points was reasonable, every court allows the defender to claim self-defense, and the protection reaches a reasonable belief that retreat was unsafe in the states that require retreat.²⁹ The line falls at reasonableness because each alternative produces a worse rule. A defender facing an apparent attacker has seconds to act and no way to confirm what the other person holds or intends, so a rule demanding accuracy would punish defenders for facts that nobody in their position could have known. It would also push defenders to wait for certainty, and certainty about a weapon usually arrives when it is too late to respond. A rule accepting any honest belief would fail in the other direction, because it would let a fearful or careless person kill on the strength of suspicion alone. Reasonableness gives full protection to those who erred without carelessness and withholds it from those who did not take care. The same sorting appears in tort and consent law, where an honest but unreasonable mistake is no defense and an honest and reasonable one excuses what would otherwise be a wrong.³⁰

A mugging that never involved a gun shows the protected side of the line. A stranger confronts a pedestrian and demands money on pain of death while pointing what looks like a gun but is really a finger pushed against the inside of a jacket.³¹ A reasonable person would take the object for a firearm, and the pedestrian also reasonably fears being shot even after handing over the money, because that has happened in the neighborhood several times lately. The pedestrian draws a gun and kills the stranger, and evidence afterward shows that the stranger, a career mugger, would never have harmed a victim physically.³² Both errors, about whether a gun existed and about whether it would be used, were reasonable, so self-defense is available despite them.

The facts of People v. Goetz supply the contrasting pole, and they matter here only for the mistake point. A rider on a New York City subway shot four youths after one or two of them approached and asked for five dollars.³³ Taking the illustration as it is usually framed, the rider carried an unlicensed loaded pistol and fired at each of the four, including one sitting on a bench who apparently posed no imminent threat. The rider later conceded that he did not think the youths had a gun and pointed instead to a fear of being maimed that grew out of earlier muggings.³⁴ Most states hold that an unreasonable mistake costs the defender the claim, and a fear that comes from the defender's past rather than from anything this encounter displayed is the kind of belief that fails.³⁵ What separates the two defenders is the link between belief and scene: the pedestrian's belief tracked what was visible and what the neighborhood had shown, while the rider's fear rested on his own history and on no sign of a weapon.

What counts as reasonable depends on the circumstances the defender faced, including what the defender knew. In tort law, a person who feigns a threat against someone known to be unusually nervous after a recent mugging risks a justified defensive response that would not be justified against a calmer target.³⁶ The same dependence on context explains why, in prosecutions involving battering, expert testimony on the effects of battering can help the jury judge whether the defendant's fear was reasonable, although that testimony informs the question and is not itself a defense.³⁷ Both halves of the standard must be met, since the defender must honestly hold the belief and the belief must also be one a reasonable person could hold.

Hindsight is the usual way this issue is lost. The mugger in the pedestrian example turned out to be harmless, yet the defense holds because the inquiry is confined to what the defender could perceive at the moment of the act, and the harmlessness was learned only afterward.³⁸

A successful mistake claim also complicates the classification of homicide taught at the start of this chapter. If the apparent attacker posed no deadly threat, the killing was in fact unnecessary, which resembles an excused killing, yet the defender receives the same complete acquittal as one who read the facts correctly. Self-defense can be described as a justification when the reasonable belief is well founded and as an excuse when it is reasonable but wrong, and courts conventionally call both a justification.³⁹ Under either label, a defendant who meets the requirements is acquitted.

Exam Analysis Steps

Because the result depends on how the belief is graded, a mistake problem is best handled by locating the belief first and grading it second. The steps are these:

Identify which belief proved wrong: whether an attack was coming, whether the force was unlawful, whether deadly force was needed, or whether retreat was safe.
Confirm that the defender actually held that belief when using force, since an invented fear gives the reasonableness inquiry nothing to evaluate.
Ask whether a reasonable person with the information available to the defender at that moment would have held the same belief, ignoring facts discovered afterward.
If the belief was reasonable, test the remaining requirements as though the facts were what the defender believed, and if it was unreasonable, treat the perfect defense as lost in most states and ask whether the jurisdiction recognizes imperfect self-defense.

Imperfect Self-Defense

A reasonable mistake about the need for force leaves self-defense intact, but a defender whose belief or conduct falls short of that standard faces a harsher prospect. At common law, self-defense was an all-or-nothing proposition: the defender was acquitted if every requirement was met and convicted of murder if any one was missing.⁴¹ Imperfect self-defense fills the gap between those two outcomes. It applies only when the defender kills, and only when the defender cannot succeed with a claim of perfect self-defense. Its function is to reduce what would otherwise be murder to voluntary manslaughter.⁴² A nonfatal shooting carries no murder charge, so when the victim survives there is nothing for the doctrine to reduce.

The doctrine makes sense once unlawfulness is separated from malice. Murder requires malice aforethought, the culpable mental state that marks a killing as murder, and a killing can be unlawful without carrying it. A perfect defense removes the unlawfulness altogether, which is why it ends in acquittal. Imperfect self-defense leaves the unlawfulness in place, because some requirement of the full defense was not met, while a mitigating circumstance explains why the killing lacked malice. Provocation reduces murder to manslaughter on the same footing, since both doctrines assume that the killing was unlawful but that a mitigating circumstance took away malice aforethought.⁴³ Two situations produce this result in the jurisdictions that recognize the doctrine, and each has its own reason and its own limit.

The first situation involves a defender who started the fight without committing a felony and is then forced to kill when the other person answers with deadly force. The standard illustration follows the reasoning of State v. Norris: A punches B in the nose, B retaliates by trying to kill A with a knife, and A kills B in self-defense.⁴⁴ A has no perfect defense, because the original battery precipitated the altercation, so the killing is unlawful. Yet A did not begin with an attempt to kill, and the deadly danger came from B's escalation, so the killing that followed lacked malice. The verdict that fits is voluntary manslaughter rather than murder.⁴⁵

The Model Penal Code reaches a different result on the punch-and-knife facts. Its aggressor limit withholds the defense of deadly force only from an actor who provoked the encounter with the purpose of causing death or serious bodily harm, and a punch in the nose does not meet that description. The puncher may therefore raise a perfect self-defense to the killing, although the puncher remains guilty of the original battery.⁴⁶ Jurisdictions that follow the common-law rule downgrade the homicide to manslaughter, while the Code acquits of the homicide and punishes only the first blow.

The reduction has a firm limit, because it is unavailable when the original attack was felonious. Under the rule illustrated by Commonwealth v. Blackman, an assailant who attacks with a knife, is repelled, and then shoots the victim as the victim turns to kill the assailant is guilty of murder, not manslaughter.⁴⁷ The reason lies in what the first attack created. A person who begins with a deadly attack has produced the lethal danger from which the later killing flows, and nothing in that sequence suggests that the killing lacked malice. The punch case and the knife case differ in a single respect, the seriousness of the first wrong, and that difference separates manslaughter from murder. Either kind of aggressor can sometimes regain a perfect defense by total withdrawal, which requires more than a strategic retreat and must be communicated so that the other party can perceive it. Juries are wary of that claim because the victim is not alive to say whether the withdrawal was communicated, and the defendant in State v. Mayberry, who made it, was convicted on retrial.⁴⁸

The second situation involves no aggressor at all. The defender honestly believes that deadly force is necessary to prevent death or grievous bodily harm, but the belief is unreasonable, as in Shuck v. State.⁵⁰ Each half of that description does separate work. The unreasonableness fails the objective standard taught in the preceding section on reasonable mistake, so in most jurisdictions the killing is unlawful and the perfect defense is lost. The honesty of the belief negates malice, because a person who truly fears death and misjudges the danger has not acted with the state of mind that murder requires. The result is voluntary manslaughter.⁵¹

Recognition of the doctrine is uneven. Some jurisdictions refuse to apply imperfect self-defense to an unreasonable belief and treat the killing as murder, as in People v. Manzo.⁵² If Dale's jurisdiction follows that approach, the verdict is murder, so the reduction to manslaughter depends on the jurisdiction and cannot be assumed as the automatic consequence of an unreasonable belief.

The Model Penal Code reaches a related result without using the label. Under § 3.09(2) it makes the degree of guilt depend on the defender's culpability as to each element, so a defender who honestly but unreasonably, meaning negligently, believes that killing is necessary can be convicted of negligent homicide.⁵³ The Code measures blame by the mental state the defender actually had about the justifying facts, which places an honest but careless belief in the category of negligence and sets the offense at that grade.

Exam Analysis Steps

Because the doctrine operates only after the perfect defense fails, it is best run as a sequence that tests the perfect defense first and the reduction second. The steps are these:

Confirm that the defender actually killed the attacker, since imperfect self-defense has no role when the victim survives.
Test the perfect defense first, because a defender who satisfies every requirement is acquitted and never reaches the reduction.
Identify why the perfect defense failed, whether because the defender non-feloniously started the fight and met deadly escalation, or because the defender honestly but unreasonably believed deadly force was necessary.
Check the limits by asking whether the original attack was felonious, whether the jurisdiction rejects the doctrine for unreasonable beliefs, and whether the Model Penal Code's treatment of the puncher or of negligent belief controls instead.

The doctrine also completes the classification of homicide that opened this chapter. A killing in perfect self-defense produces a complete acquittal, because the law treats it as justified or excused. Imperfect self-defense lands elsewhere. The killing remains unlawful, so it is neither justified nor excused, and it falls into the residual category of criminal homicide where failed self-defense claims end up.⁵⁵ What the doctrine changes is the grade within that category: the mitigating circumstance that took away malice moves the offense down from murder to voluntary manslaughter, so the defender is punished, but for the lesser crime.