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  • Writer's pictureSami Farhat

Legal Insanity and Criminal Responsibility: When "Guilty" Doesn't Mean Guilty.

Protecting society at large and the defendant's rights. What is legal insanity and why is it so controversial?

"Almost everyone’s responsible for everything they do almost all the time."

- Park Dietz, M.D., Forensic Psychiatrist

While few terms evoke as strong a reaction as legal insanity, it is often misunderstood or conflated with competency or seen as a "get out of jail free" card. Although many do not fully understand the threshold or implications of such a finding, the term legal insanity has been frequently spotlighted due to high-profile cases, such as the attempted assassination of President Ronald Reagan or the tragic drowning of five children by their own mother, Andrea Yates.

First and foremost, it is important to note that insanity is not a clinical term. It is a legal term used to denote a lack of criminal responsibility. In order for a defendant to be found guilty of most crimes, there must be sufficient evidence for both the actus reus (the physical act constituting an offense) and the mens rea (the mental intent necessary to commit the crime). The insanity defense is derived from the argument that a defendant’s mental state at the time of the crime may have negated their mens rea. In other words, the defense will argue that they were not criminally responsible despite having committed the crime.

Legal Insanity vs. Competency

Terms such as insanity and competency are frequently misunderstood or used synonymously. However, they are vastly different concepts with significant differences in consequences and implications. As explained in the previous blog post, Competency to Stand Trial reflects a constellation of adjudicative capacities necessary for successfully navigating through a trial or criminal proceedings. It is a reference to the defendant’s mental state during the present legal proceedings. Insanity, on the other hand, pertains to the defendant’s mental state at the time of the crime and how this impacted their behavior. Thus, it requires a retroactive reconstruction of the defendant’s mental state, typically through clinical interviews and collateral sources (e.g., police records, medical records, interviews with family members).

Importantly, while these terms are far from synonymous, there are patterns across the two concepts that are helpful to consider. For example, it is not uncommon for a mentally ill defendant to be found incompetent to stand trial following the commission of a crime and subsequently found to have been legally insane. The temporal relationship between the crime and competency is often crucial when determining criminal responsibility. Similarly, if a defendant is evaluated shortly after a crime and found to be competent to stand trial, this may, but. not always, provide support for intact criminal responsibility.

The Insanity Defense

One of the most important features of an insanity defense to understand is that it is an affirmative defense. What this means is that the defendant admits to committing the crime; however, he or she then submits evidence that negates their criminal liability. Importantly, this means that the burden of proof rests on the defense. In the case of an insanity defense, this negation would be due to a mental illness that impaired their capacities relevant to criminal responsibility and is entered as a plea of Not Guilty by Reason of Insanity. While every jurisdiction has slightly different language, statutes typically look at the defendant’s mental state at the time of the offense, whether the defendant could appreciate the wrongfulness or criminality of their conduct, and in some jurisdictions, whether they were capable of conforming their behavior. This last part is sometimes referred to as the volitional prong, which speaks towards whether the defendant was incapable of behaving differently.

Statutes related to criminal responsibility are typically a threshold matter. That is, there must first be a qualifying mental condition. For example, in the State of Michigan, the defendant must have had a statutorily defined mental illness or intellectual disability. The term mental illness is a strictly defined concept and is not derived from the more colloquial and clinical term. It is defined as follows:

A substantial disorder of thought or mood that significantly impairs judgment, behavior, capacity to recognize reality, or ability to cope with the ordinary demands of life.

When considering what could qualify as a mental illness, one must consider what constitutes a substantial disorder of thought or mood. Traditionally, the two most common conditions are those of a psychotic or manic nature, as these are arguably two of the most severe forms of psychopathology that often entail impairments that are legitimately outside of the individual’s control.

After establishing a qualifying mental condition, there must then be, as a result of that condition, impairments in the related capacities. While many believe that the mere presence of a mental illness or intellectual disability could render one legally insane, this is far from the truth. It is the impairments in capacities, and not the severity of the mental condition, that can lend support to a finding of insanity. As such, it is not uncommon for a mentally ill individual to be found criminally responsible, and consequently, convicted and sentenced to prison.

Implications of an Insanity Verdict

The public perception of the insanity defense is often characterized by concerns of misuse or abuse. However, many critics of legal insanity may not fully understand the implications of such a verdict. While it is easy to view this as a way to avoid punishment for a crime, individuals who are successfully acquitted by reason of insanity do not simply re-enter the community. Rather, they are typically committed to a secured psychiatric facility for an indeterminate period of time. These facilities are often maximum security where the defendant-turned-patient is housed, monitored, and observed for extensive periods. In fact, this can often be for a longer period of time than they would have been in prison. Facilities typically consider several factors in determining the length of stay for such an individual, including the severity of the offense, dangerousness, insight, and need for continuing treatment.

In this regard, it is important to understand that a finding of insanity has two primary functions: The first is to protect the rights of the defendant by not convicting and sentencing an individual who was not criminally responsible. The second is to protect society as a whole by avoiding the release of a potentially dangerous individual.

Another common misconception is that the insanity defense is nothing more than a ploy for defendants to get an "easy out" by feigning impairments. Available research indicates that the insanity defense is only raised in approximately 0.5-1% of felony cases across the United States. Of that, only 15-25% are successfully argued and acquitted . This means that successful insanity pleas may be as low as 0.075% of felony cases. This is an incredibly low number.

It is also important to note that forensic evaluators are skilled and trained in the detection of malingering and deception. Defendants attempting to feign impairment or malinger a lack of criminal responsibility are rarely successful. Furthermore, because the burden of proof rests on the defense, a malingering defendant is more often than not presumed to have been criminally responsible.

Forensic Psychology's Role

While forensic evaluators are not detectives, there is, to some degree, a sense of detective work in reconstructing a defendant’s behavior and mental state. We not only interview the defendant, but we review police records, medical records, watch footage of the defendant’s arrest, and speak with witnesses and relatives. One of the most important components of forensic work is that our opinions should be predicated on a variety of sources and not based on one single data point.

Criminal responsibility evaluations are the second most common forensic referral (after Competency to Stand Trial). Unlike competency evaluations, which strive to prevent unconstitutional proceedings and focus on the present, criminal responsibility evaluations strive to explore the defendant’s intents, motives, and thought processes at the time that they committed the crime. As such, these evaluations can be notably incriminating, in that the defendant does provide their own account of the offense, which is equated to a confession. Disclosures for criminal responsibility evaluations therefore are lengthy and should entail the guarantee that the defendant fully understands the nature, purpose, and implications of such an assessment. If a defendant does not understand these points, then one should, at the very least, consider whether the defendant is competent to stand trial, as participating in such an evaluation can equate to significant legal decision-making.

When conducting a criminal responsibility evaluation, the first issue to be determined is whether the defendant had a qualifying mental condition. To reiterate, this is a threshold matter. A qualifying condition is required in order for the capacities to be impaired, and as such, a lack of condition automatically presumes that the capacities were intact.

When assessing whether a defendant was criminally responsible, we as forensic evaluators look at many sources of information and consider a variety of plausible explanations for the criminal behavior. Concerning the capacity to appreciate the wrongfulness of their conduct, we consider all the facts of the case. Did the defendant flee from the scene? Did they attempt to evade detection and capture? Did they coerce the victim or witnesses to remain silent? All of these facts suggest that the individual understood what they were doing and that it was wrong, which would not lend support to a successful insanity defense. On the other hand, if the defendant committed a random act of violence in broad daylight in front of a police station, then there may be concern that they were not appreciative of their conduct, it's wrongfulness, or the potential consequences of engaging in the act.

Regarding the volitional prong, or the capacity to conform, we often study the defendant’s history of behavioral problems, including those surrounding the time of the crime. For example, if a defendant planned and organized their crime (e.g., waiting until nighttime to break into someone’s home), this would suggest that their behavior was opportunistic. This deferral of behavior until an opportunity presented itself would suggest an intact capacity to have conformed their behavior. In other words, if they could have waited until such an opportunity, then they could have likely waited even longer. On the other hand, if a defendant sets fire to a home at the command of voices who they believe to be God, and therefore omnipotent and omniscient, then they may have experienced a legitimate inability to have controlled their behavior.

As forensic evaluators, we often look at the defendant’s motive for the crime. For example, behavior that is rooted in anger, jealousy, or emotional dysregulation (e.g., a husband killing his wife for infidelity) is not typically considered to be grounds for legal insanity, as the behavior stemmed from reality-based emotions and a failure, rather than inability, to control their behavior. This is in stark contrast to crimes with no inherent motive (e.g., a random, unprovoked murder of a stranger) or those of a psychotic motivation. For example, if an individual believes their neighbor is going to murder them and their family, they might think the only way to protect their household is by killing the neighbor first. This belief could support a claim that the individual's motive was not based in reality and that they experienced a genuine, imminent compulsion to act in a way that would be reasonable if their paranoid beliefs were true. This concept of reasonableness within the unreasonable mind, or sanity within insanity, is a fascinating component of criminal responsibility evaluations.

While there is no universal rule, there are certain types of crimes that are rarely due to insanity. One of the most common examples of this is sexually based offenses, as these typically include strong personal motivations, such as power, control, or sexual gratification. These are rarely related to mental illness and are more often indicative of a volitional breach of morality rather than a legitimate inability to appreciate it. This speaks towards one of the founding principles of forensic practice, which aims to assess the defendant’s capacity and not simply their willingness for lawful conduct.


Legal insanity has a longstanding role in judicial proceedings and forensic work. It is important to understand what goes into our evaluations and the court’s associated verdicts, as the public’s perception of the defense may not always be commensurate with the reality on the ground. Legal insanity is an incredibly high threshold to establish, and the vast majority of attempted defenses are not successful.

Sami Farhat, Ph.D.

Forensic psychologist and owner of ForenPsych Evaluations

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