Defining Product

Defining Product

The causal link requirement turns on a single word, and the opinion that announced the Durham rule never defined it. Durham told juries to acquit an accused whose unlawful act was the product of mental disease or defect, yet critics soon observed that both "product" and "mental disease or defect" were ambiguous, so jurors had little guidance on the central question of responsibility.¹ The explanation of "product" came later, in Carter v. United States, decided in 1957, when the court reviewed a trial instruction that had tried to define the word and found it inadequate.² The trial judge had told the jury that the act must be the consequence, growth, natural result, or substantive end of the mental abnormality, produced in direct relation to it and not in a minor or nominal way. The appeals court held that this instruction was neither adequate nor sufficiently accurate. It did not reverse on that ground alone, but because the case had to be retried the court used the occasion to explain the rule.³

Carter responded with an account of the word instead of a replacement slogan. The court observed that "product of" in Durham and "except for" in the earlier Douglas decision were never meant to compress the whole rule into one expression, because no single phrase could do that work and the matter had to be explained, not merely stated.⁴ The explanation serves a purpose that the two subsections below make concrete. The element exists to separate a disease that operated on the act from a disease that merely coexisted with it, since the criminal law punishes a will that freely chooses wrongdoing and an accused whose illness drove the act was not choosing freely.⁵ A definition of product therefore has to answer one question: did the illness make the difference? Carter's answer, the but-for gloss, comes first, and the harder setting in which the illness reaches only part of the person's mental life follows it.

But-For Causation

Carter added a qualifier to the but-for idea: the relationship between the disease and the act, whatever it may be in degree, must be critical in its effect on the act.⁶ By critical relationship the court meant one that is decisive, determinative, and causal, the idea carried by expressions such as because of, except for, without which, and but for, so that the disease made the effective or decisive difference between doing and not doing the act.⁷ The phrase "whatever it may be in degree" means the test sets no minimum quantity of illness and measures effect instead. A severe illness that left the act untouched fails the standard, while a milder disturbance that actually decided the outcome satisfies it. The primary rule states the same standard from the other side: the offense is the product of the condition when the defendant would not have committed it but for the disease or defect.⁸

The standard is framed in terms of inference, so the question is what the record permits the jury to conclude. The relationship must be such as to justify a reasonable inference that the act would not have been committed if the person had not been suffering from the disease.⁹ The inference rests on two bodies of fact taken together, the facts concerning the disease and the facts concerning the act, which must justify the conclusion that but for this disease the act would not have been committed.¹⁰ Carter added that the short phrases "product of" and "causal connection" were never meant to be precise in the way chemical formulae are, which is why the court described the inference instead of relying on the labels.¹¹

The contrast with the rejected instruction shows what the but-for formulation changes. An instruction built on growth and natural result asks whether the act is the kind of thing the illness typically yields, which invites the jury to compare the act with the usual symptoms of the diagnosis. The but-for formulation asks whether the act would have occurred without the illness, and that question can be answered for an unusual act as readily as for a typical one. The premise of the doctrine explains why the line falls at the decisive difference. Carter described a crime as an act together with a vicious mind prompting it, and treated an accused who, because of illness, is not a free agent or is not choosing freely as outside the premise on which punishment rests.¹² An illness that made the decisive difference shows the act was not a free choice, while an illness that made no difference leaves the act as freely chosen as anyone else's.

The two bookkeepers share a diagnosis, a time frame, and an act, and differ in the single fact that separates them: whether the illness supplied the reason for the diversion. Students lose this issue when they equate a disease that merely accompanied the act with one that caused it, because the diagnosis answers only the first of the two key factors in the defense.¹³

Illness of Limited Scope

Carter identified the setting in which the causal question is easiest and the setting in which it is hardest. If the disease produces a mental derangement of such character as necessarily to influence the accused's every action, the court said there is no further problem.¹⁵ The difficulty comes from illness of lesser scope, which the authorities of a century earlier called "partial insanity."¹⁶ The two cases differ because of what the existence of the disease already tells the jury. A derangement that reaches every action cannot have missed the act in question, so proof of the disease carries the causal link with it. An illness of narrower reach leaves the rest of the person's mental life working normally, and the diagnosis alone cannot say whether a particular act came from the affected part or from the part that was intact.

The but-for inquiry is built to answer that uncertainty, because it directs the jury's attention from the diagnosis to the act. Carter described Durham as extending the defense to all acts that would not have been committed except for a mental illness of the accused, and the description is act-specific: the question is asked about each act separately.¹⁷ The court also noted that the earlier impulse formulation connoted suddenness, while many recognizable diseases of the mind involve slow deterioration, brooding, depression, or constant pressure.¹⁸ The product inquiry reaches those conditions because it asks what produced the act and says nothing about how quickly the illness acted. The same feature limits the defense, since an illness confined to one area of the accused's thinking excuses only the acts that the area actually produced.

One illness produced two different answers because the jury put the causal question separately for each charge. Students lose this issue when they treat an illness that touched only one area of the accused's thinking as an excuse for every offense committed while it lasted, since only an illness that necessarily influences every action carries the causal link with it.¹⁹ Who answers the causal question, and how reliably anyone can answer it, are matters for the sections on the jury and expert roles and on the criticisms of the test.

But-For Causation

The trial instruction reviewed in Carter v. United States shows what the but-for gloss was meant to replace. The trial judge told the jury that the act must be the consequence, growth, natural result, or substantive end of the mental abnormality, and that it must be produced by the unsound condition not in a minor or nominal way but in direct relation to it.²¹ The court of appeals held that this instruction was not adequate or sufficiently accurate.²² It did not treat the instruction as reversible error standing alone. The case had to be retried anyway, so the court used the occasion to explain the rule that Durham had announced.²³ The weakness of the instruction shows once its words are read as a juror would read them. Growth and natural result point the jury toward whether the act resembles what the illness typically produces, and the warning against a minor or nominal connection sets a floor on how large the link must be. Neither phrase asks whether the act would have happened anyway.

Having found the instruction wanting, the court declined to offer one better slogan in its place. The words “product of” in Durham and “except for” in the earlier Douglas decision were never attempts to compress the whole rule into a single expression, and the court said that no single phrase could do that work, because the matter had to be explained and not merely stated.²⁴ The explanation begins by removing any suggestion that a diagnosis settles the question. A mental disease or defect, standing alone, does not relieve the accused of responsibility. There must also be a relationship between the disease and the act, so the defense rests on two key factors: a mental disease, and a critical relationship between that disease and the alleged criminal act.²⁵

The word critical carries the doctrine. Carter used it to mean decisive, determinative, and causal, the idea contained in the phrases because of, except for, without which, and but for, so that the disease made the effective or decisive difference between doing and not doing the act.²⁶ The relationship may be of any degree, provided it is critical in its effect on the act, which means the standard measures what the illness did to the act and not how much illness there was.²⁷ A mild disturbance that actually decided the outcome therefore satisfies the standard, while a severe illness that left the act untouched does not. The primary statement of the rule puts the same idea in its shortest form: the offense is the product of the condition when the defendant would not have committed it but for the mental disease or defect.²⁸

Because the but-for question asks about a world that did not occur, the court framed it as an inference to be drawn from the record and not as something the record must prove with certainty. The facts concerning the disease and the facts concerning the act must be such as to justify reasonably the conclusion that but for this disease the act would not have been committed, and the court added that product of and causal connection were never meant to be precise in the way chemical formulae are.²⁹ In practice the jury looks at two bodies of evidence together: what the illness is and how it operates, and what the act was and why it was done. When the evidence traces the reason for the act to the illness, the inference is available. When the evidence supplies a reason that stands on its own, the inference is not. Critics later argued that no one can say with confidence what a person would have done without the illness, a difficulty taken up in the section on the criticisms of the test.³⁰

The reason for choosing but-for language over looser words follows from what the defense is for. Carter grounded the defense in the premise that criminal punishment falls on a free agent who chooses wrongdoing freely, so an accused who, because of illness, was not acting freely in respect to the act stands outside that premise.³¹ The only question that tests whether illness took away the choice is whether the accused would have acted anyway. Words like consequence and natural result let a jury find a loose connection between disease and act without ever finding that the disease made the difference, and a loose connection would excuse conduct that the illness did not cause. Equating product with decisive prevents that result, because a diagnosis then excuses only what it produced. The same reasoning explains why the test reaches illnesses that develop slowly. The court observed that the older impulse formulation carried a connotation of suddenness, while many recognizable mental diseases involve slow deterioration, brooding, depression, or constant pressure, and the but-for question does not depend on how quickly the illness acted.³²

The two defendants share a diagnosis and differ in a single fact, what the evidence shows about the reason for the act, and that fact decides whether the relationship is critical. The instruction rejected in Carter could not separate them, since a jury told only to look for a natural result or a more than nominal connection could call both acts products of depression. The but-for question separates them, because it requires the jury to ask of each act whether it would have occurred without the disease. Students lose this element when they treat a diagnosis, or an act that resembles a symptom, as proof of product, since the record must support an inference that the act would not have been committed but for the disease.³³

Illness of Limited Scope

The but-for question has an easy setting and a hard one, and Carter v. United States named both. The easy setting is a disease that produces a mental derangement of such character as necessarily to influence the accused's every action, and for that situation the court said there is no further problem.³⁵ The reason follows from what the causal question asks. The jury must decide whether the disease made the decisive difference to the act, and a derangement that reaches every action reaches this one too. Proof of the disease therefore carries the causal link with it, and the critical relationship can be inferred without a separate showing about the particular act.³⁶

The hard setting is an illness of lesser scope, which the authorities of a century earlier called "partial insanity."³⁷ That label is older vocabulary for an illness that does not reach every action. It affects one part of a person's thinking, such as a delusion confined to a single subject, while the rest of the person's mental life keeps working normally. In that setting the existence of the disease says little about any particular act. The diagnosis cannot tell the jury whether the act came from the affected part of the mind or from the part that stayed sound, and that open question is the one the critical-relationship requirement exists to settle.

Carter stated the defense as two key factors, a mental disease and a critical relationship between that disease and the alleged criminal act.³⁸ With a pervasive derangement, the second factor follows from the first. With an illness of limited scope, the second factor becomes an independent question that the evidence must answer for the act charged. The reason lies in the premise of the defense. The court grounded it in the idea that criminal punishment falls on a free agent who chooses wrongdoing freely, so an accused who is not acting freely in respect to the act stands outside that premise.³⁹ An accused whose illness had no part in producing a given act chose it as freely as anyone else. If the law presumed a connection from the diagnosis alone, it would excuse acts the illness never influenced, and the defense would drift away from the free-agent premise that justifies it. Requiring the link to be shown for the particular act keeps the defense tied to the actual source of the conduct.

Because the inquiry attaches to the act, a single defendant can receive different answers for different acts. Carter described the product rule as reaching acts that would not have been committed except for the accused's mental illness, and that description is act-specific.⁴⁰ The jury therefore asks the but-for question separately for each charge, looking at what the illness is and at what prompted the particular act.

One diagnosis produced two answers, and the only fact that changed was whether the illness supplied the reason for the act. Students lose this issue when they treat a delusion confined to one subject as an excuse for every offense committed while it lasted, since only an illness that necessarily influences every action carries the causal link with it.⁴¹ The pervasive case is the contrast: there the diagnosis does most of the causal work, and the jury's task is correspondingly light. How the jury and the psychiatric witnesses divide the causal question, and how reliably anyone can answer it, are taken up in the sections that follow.