Concept
Elements of the Test
M'Naghten Rule
Elements of the Test
The traditional rule is built as a chain of three links, and each link depends on the one before it. The defendant must prove (a) a disease of the mind, (b) that the disease caused a defect in his reasoning, and (c) that, as a result, at the time of the charged conduct he lacked the capacity either to understand the nature and quality of his actions or to know that they were wrongful.1 The same structure can be divided into a disability and a result. The disability is a defect of reason produced by a disease of the mind, and the result is a failure of knowledge, defined entirely in terms of cognition, that takes one of two forms.2 The words as a result in the third element hold the chain together: the incapacity must trace back through the defect of reason to the disease, so a lack of knowledge that comes from some other source does not satisfy the rule. Some sources break the same content into four parts (time of the offense, defect of reason, mental disease as its cause, and inability to understand the act's nature or to tell right from wrong), but the substance is identical.3
Each link screens out a different kind of defendant, and seeing what each one screens out makes the elements easier to apply. The disease-and-defect requirement reserves the defense for people whose reasoning is actually impaired, which excludes the defendant who is merely troubled, enraged, or morally corrupt. The two knowledge endpoints keep the inquiry on blameworthiness, because a person who cannot grasp what he is doing, or that it is forbidden, cannot meaningfully choose to do wrong. The timing requirement ties the excuse to the moment of choice. A defendant's condition last year, or after arrest, says nothing about what he was capable of knowing when he acted.
The final element ends in two alternatives, and proof of either one is enough.4 The first is often called cognitive incapacity. It asks whether the defendant knew what he was doing, and it corresponds roughly to the mens rea requirement of many offenses. The second is moral incapacity. It goes further and asks whether a defendant who did know what he was doing still had the capacity to know that it was wrong.5 Two illustrative defendants show the difference. One thinks his victim is a dog, so he does not know what he is doing. The other knows he is killing a living creature but believes a dog ordered him to do it, so he does not know that his act is wrong. The first falls within the first prong and the second within the other, and each qualifies without the other.6
That contrast points to the most common exam trap in this area: a diagnosis alone never satisfies the test. A fact pattern may say that the defendant was previously found insane in another case, or that he has been diagnosed with a serious mental illness, or that his behavior was bizarre. None of that answers the question, because the elements must be present at the time of the offense in question.7 The defendant also carries the burden. The rule speaks of what he proves, and the original formulation demanded that the defense be clearly proved, a point taken up in detail in the section on proof.8
Steps 4 and 5 usually carry the analysis, because a stem that supplies a diagnosis seldom leaves the disease element in real doubt. The dispute is over what the defendant was capable of knowing when he acted. The three subsections that follow take the links in order: first the disease of the mind and the defect of reason it must cause, then the nature-and-quality prong, and then the wrongfulness prong.
Disease of the Mind
The first link in the chain, disease of the mind, sounds like a medical category, and a reader might expect the element to ask whether a psychiatrist would call the defendant's condition an illness. Courts do not read it that way. They have shown little concern with the nature of the disease, provided that it in fact produced the defect of reason the rule requires.10 The phrase therefore works as a legal gateway. Any condition passes through it if the condition actually impaired the defendant's reasoning, and a condition that left his reasoning intact does not, however serious its clinical label.
The reason is that the defense serves a different purpose from clinical diagnosis. It exists to sort out who is an appropriate subject for criminal punishment and was never designed to define psychiatric illness, which is why the familiar objection that the test departs from modern psychiatric thinking misses what the test is for.11 Putting the legal weight on the defect of reason produces two practical results. Defendants whose conditions have very different clinical causes, but who are equally unable to grasp what they are doing, are treated alike. And a defendant whose reasoning stayed intact cannot borrow an excuse from a diagnosis. Both results follow from judging the condition by its effect and giving its name no weight.
Because the label carries no weight, the category is broad. "Disease" is read to include a congenital defect (an impairment present from birth) or a traumatic injury, so a defendant who was born with an impairment, or whose brain was damaged in an accident, can satisfy the element as readily as one with a classic psychosis.12 There is also authority, including a Wisconsin decision from 1940, suggesting that low intelligence will suffice.13 Because that authority is limited, an exam answer should use it to show that even impaired intellect can qualify when it produces the defect, and should not present it as a rule every jurisdiction follows.
The second half of the element decides most fact patterns. The formulation requires a defect of reason from disease, so the condition must cause the cognitive defect, and a condition that merely coexists with working reason does not meet the element. A defendant previously diagnosed with schizophrenia strangles his fiancée after telling his psychiatrist that a robot has hidden her and taken her place, and that he must disable the robot before he can look for her. If he was telling the truth, the illness produced a belief that he was destroying a machine, which is a defect of reason bearing directly on what he thought he was doing.14 The diagnosis opens the door, but the belief it generated carries the analysis.
The element fails where the condition leaves the necessary knowledge in place. A defendant who knew he was poisoning the Governor and knew that the act was against the law is not insane under the test, whatever mental illness may lie in the background, because nothing in his condition prevented that knowledge.15
On an exam, a stem that supplies a diagnosis should prompt a single question: what did the condition do to this defendant's reasoning at the time of the act? Planning, concealment, and statements showing that the defendant knew the conduct was unlawful point toward intact reasoning, while evidence of a distorted perception of what he was doing points toward a defect.16 The next section takes up the first thing such a defect can destroy, the defendant's understanding of the nature and quality of his act.
Nature and Quality of the Act
The final element of the test ends in two alternative incapacities, and the first asks whether the defendant understood the nature and quality of his actions.18 Courts have seldom discussed the phrase at length, and when they have, they have generally read it to mean the physical nature and consequences of the act.19 A defendant qualifies under this prong only if his defect of reason left him unable to grasp what he was physically doing and what that would cause. The standard illustration, drawn from the Model Penal Code, is a man who squeezes his wife's neck while believing that he is squeezing lemons.20 The narrow, physical reading follows from what the prong is for. A person who does not know what his hands are doing has no awareness of the harm he causes and so has made no culpable choice to cause it, which is why this prong corresponds roughly to the mens rea requirement of many offenses.21 A physical standard also gives the jury a question it can answer from the evidence: what did the defendant believe was happening when he acted?
The lemon illustration succeeds because the disease has corrupted the defendant's perception of reality itself. Severe hallucinations cause him to see fruit where there is a person, so the defect of reason cuts him off from the physical facts at the moment he acts.22 The commentary to the Model Penal Code explains why such a defendant sits squarely inside the defense. A deranged person who believes he is squeezing lemons when he chokes his wife is beyond the deterrent influence of the law, so punishing him would accomplish nothing and condemning him would carry no meaning.23 A threat of punishment cannot influence someone who does not know that the act it forbids is the act he is performing.
The prong fails once the defendant understood the physical consequences of what he did. Courts have required that the accused knew holding a flame to a building would cause it to burn, or that holding a person's head under water would cause death, and a defendant who had that knowledge cannot rely on this prong however ill he was.24 A bizarre motive does not change the result. The prong asks what the defendant understood about the act and its effects, and his reasons for doing it fall outside that question.25
The second defendant has lost only this prong. Because the two endpoints of the final element are alternatives, failing the physical-understanding prong does not end the defense, and he may still try to show that he did not know his act was wrong. A defendant can understand the physical consequences of an act and yet be incapable of understanding that it is forbidden, which is why it is error to instruct a jury that insanity requires ignorance of the nature and quality of the act and also ignorance of its wrongfulness.26 The relationship between the prongs runs in one direction only. A defendant who does not know the nature and quality of his act cannot know that it is wrong, whichever meaning of wrong is adopted, because the man who thinks he is squeezing lemons knows neither that he is breaking the law nor that he is doing anything immoral.27 Everyone who satisfies the first prong therefore satisfies the second as well. For that reason many courts treat knowledge of nature and quality as the mere equivalent of knowing the act is wrong, and many jurisdictions state the test only as the ability to tell right from wrong, with no mention of nature and quality.28 In those jurisdictions the lemon defendant wins on the wrongfulness language alone, and this prong merges into the next inquiry.
A few courts read the phrase more broadly. In State v. Esser, a Wisconsin decision from 1962, the court held that the phrase implies true insight into the nature of the conduct and into the fact that it was forbidden.29 The same result can be reached by giving the word know a broad construction, since appreciating an act together with its social and emotional implications takes more than abstract intellectual awareness.30 The broader reading is best treated as a point about wrongfulness, because appreciating the moral quality of an act is a question about whether the defendant grasped that it was wrong.31 The next section takes up that prong and the meaning of know within it.
On an exam, this prong is seldom the one that decides the problem. The stem will usually signal it through facts showing what the defendant thought his act physically was: a lemon, an animal, a machine, or any object other than the person he harmed. Those facts satisfy the prong, and the answer should say so briefly before turning to wrongfulness. Where the stem shows that the defendant knew what his act physically was and what it would do, the answer should state that this prong fails and move directly to wrongfulness, because the defendant keeps that alternative.
Knowing the Act Is Wrong
The wrongfulness prong takes over where the nature-and-quality prong leaves off. The M'Naghten judges framed it as a fallback: if the accused did know the nature and quality of the act, the question becomes whether he did not know “he was doing what was wrong.”33 Because the two endings are alternatives, a defendant needs only one, and it is error to instruct a jury that the defendant must lack both, since a person can grasp the physical consequences of an act and still be incapable of understanding that it is forbidden.34 That possibility is the reason the prong exists. Without it the test would excuse only defendants cut off from physical reality, like the man who thinks he is squeezing lemons, and it would convict a defendant who sees exactly what he is doing but whose illness has stripped away the capacity to see the act as forbidden. The relationship between the prongs runs in one direction. A defendant who lacks knowledge of the nature and quality of the act necessarily lacks knowledge of its wrongfulness, so this prong reaches everyone the first prong reaches and some defendants the first cannot.35
The second prong is sometimes called moral incapacity, and one illustration separates it cleanly from the first. A defendant who thinks his victim is a dog falls within the first prong. A defendant who knows the victim is a person but believes a dog ordered him to kill falls within the second, because even though he knew what he was doing, he lacked the capacity to know that it was wrong.36
The inquiry is specific to the act charged. The judges said the question is more accurately put by reference to the accused's knowledge of right and wrong “in respect to the very act with which he is charged” than by asking about right and wrong generally and in the abstract.37 A defendant therefore need not be unable to tell right from wrong across the board, and a general ability to do so does not defeat the prong.38 The reason lies in how mental illness operates. Disorders often distort one area of thought and leave the rest intact, so a person may keep an ordinary moral sense about most things while a delusion about one person or event blinds him to the wrongfulness of one act. A test requiring global moral blindness would excuse almost no one with a delusional disorder and would miss the defendants whose reasoning fails at the moment of the charged conduct.
The word “know” carries an ambiguity of its own. It can mean intellectual awareness, or it can mean moral appreciation, so a defendant may be able to say the words “killing is wrong” and yet lack the capacity to feel or appreciate the wrongfulness of killing.39 Most M'Naghten jurisdictions never define the word and leave the jury to give it meaning on the expert testimony, and of the jurisdictions that have addressed it, the great majority have favored a broad construction, as the federal insanity statute does.40 The broad reading follows from the rationale for the prong. A person who can recite the words but cannot appreciate what they mean is as blameless as one who has no idea the act is wrong, since neither made a choice with real awareness of wrongfulness. The drafters of the Model Penal Code made a related criticism of a “knowledge” standard confined to a detached or abstract awareness that does not reach the affective level.41
The same blameworthiness logic explains the other side of the line. A person who knows an act is wrong and does it anyway has chosen with awareness of wrongfulness, and the test leaves that person subject to the criminal law.42
On an exam, facts showing that the defendant understood the physical act make this prong the place where the analysis turns. The stem usually supplies the signals. Statements that the conduct was unlawful or that the defendant could be imprisoned for it point to the capacity to know wrongfulness, while objective signs that the defendant was unaware the act was wrong point the other way.43
The word “wrong” is ambiguous in a different way, which the sections that follow resolve. The judges' own language points in two directions: they spoke of acting contrary to the law of the land, and also of an accused who was conscious that the act was one he ought not to do.44 England now reads the test to require knowledge that the act was legally wrong, while American courts have not clearly settled whether “wrong” means legally or morally wrong.45 One case is clear. A defendant who knew that an act was morally wrong but did not know it was illegal gets no help, because knowledge of the law is presumed.46 The contested case is the defendant who knows the act is illegal but, because of a delusion, believes it morally right, as when he believes God commanded it, and courts divide over whether that inability suffices.47