Lack of Self-Control

Lack of Self-Control

The rules taught so far in this chapter all ask what the defendant could know: whether mental disease left him unable to grasp the nature and quality of the act, or unable to recognize that it was wrong. The test has a third feature that is easy to miss, because it consists of a question the test never asks. Under the traditional interpretation of M'Naghten, the defendant's inability to control his behavior or to refrain from committing the crime is irrelevant, and a loss of self-control caused by mental illness, standing alone, provides no defense.¹ The test is therefore purely cognitive, meaning that it concerns what the defendant knew and understood and says nothing about whether his will could follow what his mind grasped. The third rule follows directly from that structure: lack of self-control is no defense, however severe the illness that produced it.

A standard illustration shows the rule at work. A defendant is drawn to bright objects and shoplifts jewelry constantly, though he knows intellectually that the conduct is both illegal and morally wrong. He understood the nature and quality of what he was doing and he knew it was wrong, so neither cognitive prong is met, and the possibility that he acted under an irresistible impulse does not help him.² The result is easy to predict once the test is read as two questions about knowledge. Each question has an answer against the defendant, and no third question exists in which the strength of his urge could count.

The reason the test looks only at knowledge lies in what the criminal law can accomplish and whom it can fairly blame. A deranged person who believes he is squeezing lemons when he chokes his wife is beyond the deterrent influence of the law, since a threat of punishment cannot reach someone who does not know what he is doing, and condemning him would be futile.³ The defendant who knows the act is wrong and forbidden stands in a different position. A threat of punishment works by adding a cost to a choice the actor recognizes as prohibited, and that recognition is exactly what this defendant still has. Knowledge is the point at which the law's commands can still take hold, so the traditional test makes it the line between a defendant who cannot be condemned and one who can.

Calling control irrelevant requires one qualification about its scope. The rule concerns what a loss of control can accomplish as a ground for acquittal, and it leaves the admissibility of control-related evidence untouched. Behavior that a defendant could not stop is often part of the clinical picture of a mental disease, and courts in M'Naghten jurisdictions have commonly admitted evidence of aberrational behavior, including loss of control, as probative of the defendant's mental condition without regard to the formal limits of the insanity test.⁴ That evidence can help establish that the defendant suffered a disease of the mind, and it can corroborate expert testimony about a delusion. What it cannot do is replace the cognitive finding. The jury must still conclude that the disease left the defendant unable to know the nature and quality of the act or unable to know that it was wrong, so a record full of proof that the defendant could not stop himself, with nothing showing a failure of knowledge, ends in a verdict of responsibility.

The cognitive focus has long drawn criticism. Critics argue that asking whether the defendant could tell right from wrong misdirects the inquiry, and that the real question is whether he could control his behavior, and not merely whether he understood its wrongfulness.⁵ The commentary to the Model Penal Code makes a version of the point. It accepts the M'Naghten rule as sound within its range, but it finds a second and more pervasive difficulty in cases where the defendant's disorder destroys or overrides the power of self-control.⁶ Defenders of the traditional test reply that a person who knows his conduct is wrong and does it anyway is at least to some degree blameworthy, whereas a person who does not even know the conduct is wrong is not blameworthy at all.⁷ The critic points to a will that illness has overpowered, and the defender points to a knowledge that illness has left intact, so a jurisdiction that keeps the traditional test has sided with the defender.

Two responses to the criticism exist, and each is taught in its own reading. Some jurisdictions that follow M'Naghten add an irresistible-impulse test, which calls for a verdict of not guilty by reason of insanity when mental disease kept the defendant from controlling his conduct, even if he knew what he was doing and that it was wrong.⁸ The Model Penal Code places cognition and volition in a single test, under which a defendant is acquitted if, as a result of mental disease or defect, he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.⁹ The federal standard in force since 1984 has no volitional prong at all, so inability to conform conduct to the law is irrelevant in federal prosecutions.¹⁰ Volitional tests remain by far the minority approach, in part because it is hard even for professionals to separate an irresistible impulse from one that was simply not resisted.¹¹ The difference these tests make shows in a defendant whose minimal brain dysfunction leaves little ability to restrain rage but who understands that striking the victim is wrong. That defendant is not insane under M'Naghten, though under the Model Penal Code test an expert could testify that the disorder substantially impaired the ability to conform conduct to the law.¹²

On an exam the control question usually arrives as vivid behavior. The stem describes a defendant who feels powerless to stop although he realizes what he is doing is wrong, and the pull is to treat that as insanity. If the stem does not say which insanity test governs, check whether an irresistible-impulse or Model Penal Code test would change the result, because a defendant who feels powerless to stop despite knowing the act is wrong is the fact pattern that signals such a test matters.¹³ Under a pure M'Naghten test, students lose this issue when they treat a defendant's inability to stop himself as satisfying either cognitive prong.¹⁴