State Law Variations

State Law Variations

The decision in Clark lets a state confine mental-disease and capacity evidence to the insanity defense, but it permits that restriction without requiring it, so the law on mens rea varies from state to state. One recent count of American jurisdictions finds that 16 bar evidence of mental illness to negate culpability elements of any kind, 13 permit it to negate only a specific intent, and 23 allow it to negate any element.¹ The Model Penal Code sits with the last group, because § 4.02(1) admits evidence of mental disease or defect whenever it is relevant to whether the defendant did or did not have a state of mind that is an element of the offense.² Read together, the three figures mark a spectrum that runs from admission on every mental-state element, through admission on some elements, to admission on none.

Each position on that spectrum rests on a judgment about whether psychiatric testimony helps or confuses a jury deciding what the defendant actually thought. A state that admits the evidence widely trusts jurors to weigh a diagnosis alongside the other proof of intent or knowledge. A state that bars it worries that the diagnosis will pull the trial into a contest between experts, so the choice turns on how much the legislature trusts the jury with this kind of proof. The three-way count also leaves some detail out, because jurisdictions that restrict the evidence have done so in different ways, and one variation aims only at testimony about capacity.³ The four approaches below run from the most permissive to the most restrictive, beginning with the rule that admits the evidence on any state-of-mind element.

Any-Element Approach

The most permissive position, which this chapter calls the any-element approach, treats evidence of mental disease as ordinary relevant evidence on every state-of-mind element of an offense. Model Penal Code § 4.02(1) states the rule: evidence that the defendant suffered from a mental disease or defect is admissible whenever it is relevant to prove that the defendant did or did not have a state of mind that is an element of the offense.⁴ Two terms carry the rule. Relevance is the only gate, and the word element means that no category of mental state and no kind of offense is screened out in advance. One recent survey counted 23 American jurisdictions that allow mental illness evidence to negate any element, the largest of the three groups it identified, although counts of this kind depend on how each state's decisions are sorted and are best read as approximate.⁵

The reason for the rule is that a state of mind is a fact like any other, and the law makes it significant by writing it into the definition of the offense. If the prosecution must prove beyond a reasonable doubt that the defendant acted knowingly or recklessly, then anything that logically tends to show the defendant did or did not act that way bears on an issue the jury must decide. A diagnosis, together with an expert's account of how the condition shapes perception or belief, can have that tendency, so the rule asks only the question every rule of relevance asks. The approach is therefore a rule of evidence that works through the ordinary mental-state element, and it creates no separate defense.⁶ Limiting the evidence to certain offenses would also leave a defendant charged with knowledge or recklessness unable to contest an element the prosecution must prove, even though the evidence bears on that element just as it would on an intent element.

Because the evidence works through the ordinary element, the burdens stay where they normally sit. The prosecution must still prove the required mens rea beyond a reasonable doubt, whatever form the expert's opinion takes, and the defendant carries only the burden of producing evidence that raises a reasonable doubt, which is lighter than the burden of persuading the jury that an affirmative defense applies.⁷ The rule also runs in both directions, since the Code's text reaches evidence that the defendant did or did not have the mental state, and either the defendant or the government may offer it.⁸ Success also produces a different result from insanity. A defendant who raises a reasonable doubt about a mental-state element is found not guilty of the offense charged but may still be convicted of a lesser offense, so the usual consequence is imprisonment for the lesser crime, where a successful insanity defense usually leads to commitment.⁹

In practice the evidence is offered most often on premeditation and deliberation, the elements that separate first-degree from second-degree murder. Most states admit mental illness evidence to show that the defendant did not premeditate and deliberate, which reduces the offense to second-degree murder.¹⁰ Some jurisdictions also admit it on whether a killing is murder or manslaughter and on the mental states of other lesser offenses.¹¹ The any-element approach carries the same logic to every mental state, including the knowledge and recklessness found in offenses that have nothing to do with homicide, whereas some jurisdictions confine the evidence to first-degree murder.¹²

Even under this approach, each item of evidence must clear the ordinary relevance test, and the clearest illustration comes from Texas, which treats diminished capacity as a failure-of-proof argument that the State has not established the required state of mind. Texas admits lay and expert testimony of a mental disease or defect when it directly rebuts the particular mens rea of the charged offense, subject to the specific rules of evidence that govern all testimony.¹³ In Williams v. State the court found no abuse of discretion in excluding expert testimony about PTSD that did not negate the mens rea for murder.¹⁴ The opinion also recounts an earlier Texas case in which a defendant with paranoid schizophrenia killed his brother because he thought the brother was out to get him. That evidence offered an excuse for the killing and did not negate the intent to kill.¹⁵ Evidence that explains why a person formed an intent says nothing about whether the intent was formed, so the admissibility question is always relevance to the particular mental state the offense requires.

That contrast previews the specific-intent limit taught in the next section, which one survey found in 13 states.¹⁶ The any-element approach is the baseline against which each narrower regime is measured, because every restriction removes some class of mental-state element from the reach of a rule that otherwise admits the evidence on all of them.

Specific-Intent Limit

Between the any-element approach and a total ban sits a middle position that this chapter calls the specific-intent limit. Under it, evidence that the defendant suffered from a mental disease or defect may be offered to negate a specific intent, meaning a particular purpose that the offense requires beyond the physical act, but it may not be offered to negate a general intent. Several states follow this rule, as do the federal courts that follow the Brawner approach.¹⁸ One recent count places 13 states in this group, set against 16 that bar the evidence on every element and 23 that admit it on any element.¹⁹ A broader description of the same pattern says that most federal courts and about half the states permit psychiatric evidence when it is relevant to the mens rea of a specific-intent crime.²⁰ The two figures need not match, because they come from different sources that sort jurisdictions differently. The second also sweeps in states that admit the evidence on every element, since a state that admits it everywhere admits it on specific intent too. Both are best read as approximate.

The reason for drawing the line at specific intent lies in what each kind of offense asks the jury to find. A specific-intent offense turns on a purpose or belief held at the time of the act, such as an intent to steal or an intent to commit a felony inside a building. A mental disorder can alter exactly that sort of purpose or belief, for example by producing a delusion about what the defendant was doing and why. A general-intent offense requires a less elaborate mental state, so a state may judge that a diagnosis adds little to the question and that expert testimony would mostly add confusion and expense. That judgment carries a cost: a defendant whose illness explains why the defendant lacked knowledge or recklessness cannot use it on those elements, even though the prosecution must still prove them. The limit also governs only the use of the evidence on mens rea, and the insanity defense remains a separate track on which the same testimony can be offered.

The clearest illustration comes from California, which recognizes the distinction between general and specific intent and treats burglary as a specific-intent offense. In states that draw the distinction, mental illness works as a failure-of-proof argument only against specific-intent crimes.²¹ In People v. Wetmore a defendant with a long history of mental illness broke into an apartment while the occupant was away and then lived there, wearing the occupant's clothes and cooking the occupant's food. The defendant offered evidence that the illness led to a belief that the apartment was the defendant's own. Someone who believes the apartment is theirs lacks the intent to commit a felony inside it, so the California Supreme Court held the evidence admissible on the burglary charge.²² The evidence was offered to raise a reasonable doubt that the prosecution had proved the intent the charge requires, which is the use the specific-intent limit leaves open. Even a state that generally bars the evidence may let it in on a specific-intent element such as premeditation. Arizona decisions, including State v. Malone, have allowed evidence of a character trait for impulsivity to cast doubt on premeditation.²³

The limit invites a hard question: what justifies admitting the evidence against a specific intent and refusing it against a general intent? The Model Penal Code supplies no such line, since § 4.02(1) admits evidence of mental disease or defect whenever it is relevant to a state of mind that is an element of the offense.²⁴ Many states nonetheless confine the evidence to specific-intent crimes, even though the Code is broader.²⁵ The usual answer is that a disorder bears more on purposes than on simple awareness, and that answer has force. It remains a proxy, because a delusion can shape whether the defendant knew people were inside a building as surely as it can shape whether the defendant meant to steal, and ordinary relevance does not follow the label attached to the offense. The practical consequence for an exam is that the first question is how the jurisdiction classifies the charged offense, because the same testimony and the same diagnosis can come in on one charge and stay out on another.

Under the Code the same testimony would reach the jury on both charges whenever it was relevant, because § 4.02(1) draws no distinction among kinds of mental-state elements.²⁶ The specific-intent limit therefore restricts the evidence by the kind of element it is offered against. The next section turns to a restriction aimed at the form of the testimony instead, one that allows evidence that the defendant did not in fact have a mental state while barring evidence that the defendant lacked the capacity to form it.

Capacity Evidence Bans

Some jurisdictions leave the mental-state element open to mental-disease evidence and regulate the question the expert may answer. Under what this chapter calls the capacity-evidence ban, a defendant may not use mental health evidence to show a lack of capacity to form a mental state, but may use it to show that the defendant did not in fact have the relevant mental state at the time of the offense.²⁸ Wisconsin's decision in State v. Flattum is a cited example of this approach.²⁹ The ban therefore aims at the form of the testimony and leaves the element alone. The diagnosis, the expert, and the offense stay the same, and only the phrasing of the opinion changes. The Code's own wording is framed around actual state, since § 4.02(1) admits the evidence when it is relevant to whether the defendant did or did not have a state of mind that is an element of the offense.³⁰ A capacity opinion has some logical bearing on that question, so a test of relevance alone might let it in, and the capacity-ban jurisdictions are the ones that decide otherwise.

The rule has two halves, and each has its own logic. The ban rests on the nature of mens rea. A mental state such as intending to do something or knowing a legally significant fact is relatively simple and demands little cognitive capacity, so a mentally disordered defendant who lacks the required mental state will rarely lack it because of an inability to form it.³¹ Ordinarily the defendant was fully able to form the intent and did not form it on this occasion, perhaps because a delusion or a mistaken belief took its place. An opinion about general ability then answers a question the element does not ask, because the element asks what the defendant thought or meant at the moment of the act. The opinion also resembles the inquiry the insanity defense makes, which is itself framed around capacity, so it risks drawing the jury toward a defense that has not been raised and that carries different burdens. The permission half follows from the element itself. Evidence of what the defendant actually believed or intended goes straight to the fact the prosecution must prove, and excluding it as well would leave the defendant unable to contest that proof.

A scholarly example makes the distinction concrete. A mentally disordered man, lost in a deserted part of town on a cold evening and without the means to reach shelter, breaks into a building to get out of the cold. Police catch him and charge burglary on the theory that he intended to steal.³² He is innocent of burglary if he lacked the intent to steal, and his disorder is relevant because it helps explain why he got lost and needed warmth. The disorder did not, however, affect his ability to form that intent: he could perfectly well have intended to steal, and he simply did not intend it on this occasion.³³ An opinion that he lacked the capacity to intend theft would be false, yet he has a strong factual claim that the intent was absent. The actual-state framing fits his case, which is why jurisdictions with the ban see little lost by confining the expert to it.

The obvious objection is that a person who truly cannot form a mental state did not have it, so capacity evidence is relevant to whether the state of mind existed at all. The answer these jurisdictions give is that the actual-state opinion already covers every case in which incapacity would matter, and that it keeps the jury on the single question the element poses. Jurisdictions do differ on form. In most, the expert simply gives an opinion on whether the defendant, because of the disability, did or did not have the mental state, while in others the expert testifies about capacity to form it.³⁴ Under either form the prosecution must still prove the required mens rea beyond a reasonable doubt, and the defendant bears only the burden of producing evidence of the mental illness.³⁵

The word capacity also has a troubled history of its own. Diminished capacity has been framed in two ways: a mens rea variant, which is a failure-of-proof claim that the disorder left the defendant without the required mental state and so defeats the offense charged, and a partial-responsibility variant, under which the jury finds the defendant less blameworthy and convicts of a lesser offense.³⁶ California shows how the two can part ways. In the 1979 trial of Dan White, who shot and killed San Francisco's mayor and a city supervisor, the jury returned a voluntary manslaughter verdict on a diminished capacity theory, and a psychiatrist's testimony linking the outburst to high blood sugar from junk food earned the media label the Twinkie defense. The backlash led the legislature to abolish the defense of diminished capacity by statute, although evidence of mental illness may still be used to prove that the defendant lacked the mens rea the crime requires.³⁷ The parallel is loose, since California abolished a defense by name while the capacity-evidence ban limits the form of expert testimony. In both settings, though, what survives is a claim about the defendant's actual mental state, and what is cut back is the broader capacity-based theory.

On an exam, read the expert's proposed opinion for its verb. An opinion that the defendant did not intend, did not know, or believed something different is an actual-state opinion, and it is admissible wherever the jurisdiction admits mental-disease evidence on that element at all. An opinion that the defendant could not form the state of mind is a capacity opinion, and it is barred where the ban applies. The sources give no separate tally of ban jurisdictions, so the working skill is the distinction itself, and the question to put to every proffered opinion is capacity versus actual state.

Total Bans

The capacity-evidence ban regulates what the expert may say, and the specific-intent limit regulates which elements the evidence may reach. The total ban goes furthest: in these jurisdictions a mental illness that falls short of legal insanity plays no part in deciding guilt or innocence, so the evidence is heard on insanity and nowhere else.³⁹ One recent count puts 16 states in this group, against 13 that allow the evidence to negate only a specific intent and 23 jurisdictions that allow it to negate any element.⁴⁰ The Model Penal Code stands at the opposite pole, because § 4.02(1) admits the evidence whenever it is relevant to a state of mind that is an element of the offense.⁴¹

The constitutional footing for the total ban is Clark v. Arizona. The defendant there offered a psychiatrist's opinion that paranoid schizophrenia left him unable to recognize that he was shooting a police officer rather than an alien disguised as one, and the Court held that due process lets a state exclude expert testimony that a mental disorder left the defendant without a particular state of mind or without the capacity to form mens rea.⁴² That same opinion was admissible in the same trial on the insanity defense, so the ruling allows a state to hear expert testimony on one issue and shut it out on the other.⁴³ The label deserves care, because the testimony itself remains available on insanity; what the total ban removes is its use against the prosecution's proof of an element.

The practical effect follows from how the two issues allocate proof. On insanity a state may place the burden on the defendant, while on a mens rea element the prosecution keeps the burden of proving the mental state beyond a reasonable doubt.⁴⁴ A total ban leaves that formal burden where it was but removes the defendant's most direct way of contesting it, so a delusion that explains why an intent was absent cannot be put before the jury on the intent element.⁴⁵ The prosecution's practical burden shrinks as a result, which is the force of the criticism of Clark, since the evidence is as relevant and reliable on intent as it is on insanity.⁴⁶ The stakes on the two tracks also differ. A successful insanity defense usually ends in commitment, whereas mental-state evidence that defeats the charged offense usually leaves open a conviction of a lesser offense and a prison sentence.⁴⁷ A defendant whose disorder is real but falls short of the insanity standard therefore faces an all-or-nothing choice in a total-ban state.

States that adopt the ban give reasons that fall into two groups. The first is that the evidence is not relevant to mens rea or is too confusing for juries.⁴⁸ The confusion worry has concrete forms: juries may be ill equipped for psychiatric testimony that draws subtle distinctions, such as that an impairment prevented premeditation but not an intent to kill, and experts may tailor their testimony to the party who calls them.⁴⁹ The second reason can be read off the structure of the two tracks. Channeling the evidence to insanity places it where the defendant carries the burden and where success leads to commitment rather than to a lesser conviction, an arrangement that suits a state focused on public protection. The ban therefore has an internal logic, and its weakness lies in how much it costs the defendant on an element the prosecution must still prove.

The reasoning behind such exclusions has been tested by analogy in the voluntary-intoxication setting. Dissenting in Montana v. Egelhoff, Justice Souter observed that a state might argue it is irrational to admit intoxication evidence on mental state while excluding it on incapacity, because both presuppose volitional ability, and that mixing the two issues invites juror confusion.⁵⁰ He also noted that Montana had advanced no such argument, and he doubted that those arguments would justify leaving the definitions of the mental states untouched while excluding the evidence that bears on them.⁵¹

That doubt points at the policy question the total ban must answer: if a jury can be trusted to weigh the evidence on legal insanity, why can it not be trusted to weigh the same evidence on the required mental state?⁵² The confusion rationale applies to the insanity trial as well. The usual answer to the tailoring worry is closer management by the trial judge, who can require a proffer outside the jury's presence and decide whether the testimony has enough scientific support and would help the jury.⁵³ There is also a structural cost, because if evidence of an abnormal mental condition is never admitted on a mental-state element, offenses that specifically require a bad state of mind operate in effect as strict-liability offenses for abnormal defendants.⁵⁴ The Model Penal Code takes the opposite view, treating psychiatric evidence like any other relevant evidence and relying on civil commitment to protect the public if a defendant is acquitted.⁵⁵

The ban has seams all the same. In Arizona, where defendants generally cannot use evidence of mental disease or defect to show a lack of mens rea, courts have allowed it as evidence of a character trait for impulsivity that casts doubt on premeditation, as in State v. Malone.⁵⁶ Set beside the offer in Clark, the Arizona decisions show which fact moves the result. Clark's expert opined that a disorder left the defendant without a particular state of mind, an opinion the ban excludes, while the Malone line admits mental-disease evidence in the form of an impulsive trait bearing on premeditation.⁵⁷ On an exam, identify the jurisdiction's rule before weighing the evidence. The same psychiatric opinion goes to the jury on intent in a Model Penal Code state, stays out in a total-ban state, and remains available on insanity in both if the defendant raises that defense and meets its standard. Even where the ban applies, the prosecution must still prove the required mens rea beyond a reasonable doubt.⁵⁸