The Nexus Of Mental Illness And Criminal Behavior - A Psychological And Legal Analysis

Author: LawSphereX

Category: Criminal Law

Published: 2026-08-23T21:26:22.624235+00:00

Updated: 2026-08-30T07:10:38.724Z

THE NEXUS OF MENTAL ILLNESS AND CRIMINAL

BEHAVIOR: A PSYCHOLOGICAL AND LEGAL

ANALYSIS

Kanika Miglani, University Institute of Legal Studies, Chandigarh University, Punjab

ABSTRACT

Humans are generally recognized for their logical and rational abilities, which guide their behavior in society and adherence to legal norms. However, mental illness can impair an individual’s mood, cognitive functions, and understanding of right and wrong, potentially increasing the likelihood of criminal behavior. It is important to note that having a mental illness does not automatically equate to criminality; in fact, individuals with mental health issues are often more likely to be victims rather than perpetrators of crime. Moreover, there is a complex interplay between mental health and crime, as criminal activities can also impact the mental well-being of both victims and offenders. This paper aims to explore these dynamics, including the underlying causes and effects of this relationship, and will also address the relevant legal aspects involved.

Keywords: mental illness, insanity, crime, disorder, defense

INTRODUCTION

Mental illness encompasses a broad spectrum of conditions, including various disorders, anxiety, and depression, all of which impact the human mind. Unlike physical illnesses, which can be confirmed through tangible tests and diagnostic procedures, mental health conditions are diagnosed based on observed symptoms and behavioral patterns. This reliance on symptombased diagnosis can complicate the accurate identification and categorization of individuals as "mentally ill. " For instance, if someone isolates themselves and weeps due to a single failure, they would not typically be diagnosed with a mental disorder solely based on these actions, despite similarities in symptoms. This difficulty in diagnosis means that it is hard to definitively say that mentally ill individuals are more likely to commit crimes.

Often, criminal acts driven by anger, frustration, or revenge are considered part of normal human behavior and intentions (mens rea) rather than the result of a mental illness. However, this does not negate the reality of mental health issues. According to Statista, on an average, 14 per cent of Indians suffer from variations of mental health disorders in the country1. The difficulty in diagnosing and analyzing these conditions highlights the need for expert evaluation and counseling to accurately address and manage mental health problems. CAUSES OF MENTAL ILLNESS Mental health professionals recognize that the origins of mental health disorders are not due to a single cause but rather result from a complex role of biological, psychological, and environmental factors.

Each of these factors contributes in various ways to an individual’s mental well-being, creating a multifaceted picture of mental health. Biological Factors: Biologically, genetics are a crucial element in understanding mental health disorders. Studies have shown that individuals with a family history of conditions like schizophrenia, bipolar disorder, or major depressive disorder are at a higher risk of developing these disorders themselves. This genetic predisposition suggests that mental health issues can be inherited, influencing future generations. Additionally, biological factors include neurochemical imbalances and structural brain abnormalities. For example, disruptions in neurotransmitters such as serotonin and dopamine are linked to mood disorders, while 1 Ratika Rana, The Mental Health Epidemic: About 56 Million Indians Suffer From Depression, (Sept.

22, 2021), https://thelogicalindian. com/mentalhealth/mental-health-indians-30811. structural changes in brain areas responsible for emotion regulation can affect mental health. Chronic physical illnesses, such as cardiovascular disease or autoimmune disorders, can also impact mental health. These conditions often bring about persistent stress and discomfort, potentially leading to symptoms of depression or anxiety. Psychological Factors: Psychological aspects play a significant role as well. Early-life experiences, particularly traumatic events such as physical or emotional abuse, neglect, or the death of a caregiver, can profoundly affect mental health. These experiences can disrupt normal psychological development and increase the risk of developing mental health disorders like PTSD, depression, or anxiety later in life.

Moreover, ongoing psychological stress, including chronic emotional strain, relationship problems, or severe life changes, can contribute to mental health challenges. Cognitive factors, such as negative thought patterns, low self-esteem, and poor coping strategies, also play a role in the development and persistence of mental health issues. Environmental Factors: Environmental influences are equally important in understanding mental health. The social environment, including exposure to adverse conditions such as violence, poverty, or unstable housing, can significantly affect mental well-being. High-stress job environments, characterized by excessive workload, lack of control, or insufficient support, can also contribute to mental health problems.

Furthermore, societal and cultural pressures, such as unrealistic beauty standards or expectations for success, can lead to issues like eating disorders or substance abuse. The quality of social support and the presence of a nurturing environment can either buffer against or exacerbate mental health problems. Supportive relationships and a stable living environment often provide resilience against the effects of stress. Additional Factors: In addition to these primary influences, the impact of lifestyle factors and modern societal changes on mental health. The rise of social media has introduced new stressors and comparisons that can affect self-esteem and contribute to conditions such as anxiety and depression. Similarly, the fast-paced nature of contemporary life, with its emphasis on productivity and achievement, can lead to burnout and mental exhaustion.

The role of sleep, diet, and physical activity in maintaining mental health is also increasingly recognized, as poor lifestyle choices can exacerbate or contribute to mental health issues.

Overall, mental health disorders are the result of a complex interplay of these factors, rather than a single, isolated cause. MENTAL ILLNESS AND CRIMINAL BEHAVIOUR With a foundational understanding of mental illness and its causes established, we can now explore the relationship between mental illness and criminal behavior. This relationship can be examined from three perspectives:

1. How mental disorders may contribute to an individual committing a crime.

2. How mental disorders may increase the likelihood of an individual becoming a victim

of crime.

3. How being involved in crime can impact an individual's mental health.

Research suggests that certain mental disorders can make individuals more impulsive, violent, or prone to hallucinations, potentially leading them to engage in unlawful acts. For example, individuals experiencing severe mental health crises may act in ways that contravene legal norms due to their impaired judgment or altered perception of reality. According to statistics, 1 in 5 people with mental illnesses faces some kind of criminal activity at least once in their life2. Study shows that 1 in 3 Australian adults with some kind of psychiatric disorder had been arrested during a 10-year period3. However, it is crucial to note that individuals who are considered "insane" or mentally unstable may not fully comprehend the nature of their actions or recognize that their behavior is illegal. This lack of understanding can render them incapable of realizing the wrongfulness of their actions.

Despite these observations, it is essential to emphasize that mental illness does not directly cause criminal behavior. Rather, it is often the irrational or unsound behavior associated with severe mental conditions that may, in some cases, lead to illegal activities. Additionally, long-term substance abuse has been identified as a significant factor in criminal behavior, with substances like alcohol and drugs being commonly linked to criminal acts. Thus, while there is 2Mental Illness and Crime: What’s the link? , Gallant Law (Nov. 18, 2019), https://gallantlaw. com. au/mentalillness-and-crime-whats-the-link/. 3Mental Illness and Crime: What’s the link? , Gallant Law (Nov. 18, 2019), https://gallantlaw. com. au/mentalillness-and-crime-whats-the-link/.

no straightforward connection between mental illness and criminality, the irrationality and unsoundness due to severe mental health issues and substance abuse can contribute to increased criminal activity. Moving towards the second part of this correlation, it is not necessary that a person with unsound mind is always going to commit a crime. As a matter of fact, they have a tendency to be a victim of criminal activities. Reason being that they are not in full capacity of their mind to understand what, where and whom they are heading to. This makes them an easy and unproblematic target for the offenders. Disorders such as schizophrenia and substance use lead persons to make poor judgment about whom to trust. Multiple studies have shown that women with mental sickness are more vulnerable to victimization than that of men.

Sexual abuse, violence, harassment are the crimes which they are more persecuted into. A National Crime Victimization Survey found that out of 936 patients with severe mental illnesses, more than one quarter had been victims of a violent crime which is more than 11 times higher than the general population4. In New York, New York Times reporter Clifford Levy, in a 2002 Pulitzer Prize-winning exposé, illustrated how egregiously people with serious mental illness can be victimized. Residents of a board-and-care home in Queens were subjected to prostate surgery and eye surgery (mostly cataract surgery), most of which was completely unnecessary but done simply to generate Medicaid fees for the physicians involved5. The third and most unhighlighted part of the crime is the impact of it on the mental health of a person.

When any crime scene happens, no matter violent or non-violent, the effect of it can be seen not only in the victims but the offender too. The society and surroundings also bear a pressure of the incident directly or indirectly. The victims of the crimes are unquestionably the ones who are most affected mentally. The victimization has a higher risk to put a person in poor mental state. Among all the victims of crimes, most of them suffers from severe mental sickness largely anxiety and depression. The post-traumatic stress even leads to suicide in many cases. As well as when a person is incarcerated in prison, the serious toll on his mental health is quite obvious too. The identities 4Teplin et al. , Crime Victimization in Adults With Severe Mental Illness, 62 Archives of General Psychiatry 911–

921 (2005).

5 Levy & C.J, Voiceless, defenseless and a source of cash, The New York Times, (Apr. 30, 2002).

get lost, the criminals are isolated from the society and the poor environment in prison expose them to develop serious mental disorders or worsen the condition if he is already suffering from one. The mental illness among criminals can result in re occurring crimes as the relation between crime and mental illness is interdepended. The research shows that people who recidivate [the ones who returns back to the prison after they get released] are mostly the ones who reported poor mental health in prison when they first got sentenced. It is not necessary that the one should be a part of a crime [victim or offender] to be a victim of some kind of mental toll but the incidents happening with others can also stress out the others living in the society.

In their 2016 paper, “The Effect of Local Area Crime on Mental Health” Christian Dustmann and Francesco Fasani measure the mental distress of residents in response to local criminal activity. The results show that an increase in local property crime increases overall mental distress, weakens confidence, and substantially increases reported levels of depression and anxiety in urban residents6. LEGAL ASPECT OF MENTAL ILLNESS AND CRIME Recognizing the significant impact that mental illness can have on criminal behavior, the concept of mental illness or "insanity" has been incorporated into legal systems across the globe. On 20 July, 2012, in a theatre in Aurora, Colorado, a person with gun killed 12 people and injured 70 in the scene. Later, he escaped the theatre after open firing in the crowd7.

In another incident in Newton, Connecticut, a man sneaked into a school and shot dead 20 students and 6 staff members. Afterwards, he turned the weapon on himself8. In both cases, it was observed that both the offenders were the victim of severe mental illness. This left the countries shook and the concept of mental illness in law became a topic for debate and serious concern since then. While each country has its own specific laws and definitions regarding mental illness and insanity, it is generally accepted as a defense in criminal law worldwide. This means that, despite variations in legal standards and procedures, the principle that mental illness can 6Christian Dustmann & Francesco Fasani, The Effect of Local Area Crime on Mental Health, 126 Economic Journal 978-1017 (2016).

7 History.com Editors, Aurora shooting leaves 12 dead, 70 wounded, HISTORY (Dec. 2, 2013),

https://www. history. com/this-day-in-history/12-people-killed-70-wounded-in-colorado-movie-theater-shooting. 8 James Barron, Gunman Massacres 20 Children at School in Connecticut; 28 Dead, Including Killer, The New York Times, (Dec. 15, 2012), at section A, Page 1. influence criminal responsibility is a common feature in legal frameworks around the world. A famous legal maxim is regarding this concept which is “NON COMPOS MENTIS9”. It means not having control or mastery of one’s mind. Coming to the historical background of this relation, the concept of insanity in law can be seen back in 1843 in the landmark M’Naghten’s Case. In R vs. M’Naghten10, Daniel M’Naghten took a pistol and shot Edward Drummond. He believed Edward to be the British Prime Minister who has harmed his family and with a revengeful thought in mind, he delusionally wounded him and later he was found dead.

At the time of trial, it was found out that the defendant was of unsound mind. He was not capable of exercising control over his acts because of his delusion. There were also some witnesses who have never met the defendant before and supposed to give statement on his behalf. The court held that M’Naghten was not guilty and from this case, the judges formulated the M’Naghten rules (1843)11 which proved to be the important consideration for the person who wish to rely on the defense of insanity. M'NAGHTEN RULES: - ● Every person will be considered as sane person unless and until proved of unsound mind. ● The person should not know the nature and quality of the act. ● He must not be able to differentiate between right or wrong. ● The act committed must be because of the unsoundness of mind. ● The person must be of unsound mind specifically at the time of the commission of the act.

● The witnesses at the time of trial must have met and known the defendant before to confirm the unsoundness of the person. 9Jonathan Law & Elizabeth A Martin, A Dictionary of Law 138 (7th ed. 2009). 10R v. M'Naghten, 8 E. R 718 (1843). 11Asokan TV, Daniel McNaughton (1813-1865), 49 Indian Journal of Psychiatry. 223-224 (2007).

Other than M’Naughten Rules, there were few other tests and theories which were used as the grounds for the insanity as a defense. They were- ● IRRESISTIBLE IMPULSE TEST: This test posits that if a defendant, despite being aware of the nature of their actions and able to distinguish between right and wrong, is unable to control their behavior due to a mental illness, they will not qualify for the insanity defense. For instance, if an individual experiences a disorder that causes extreme anger and, during an episode of uncontrollable rage, commits an act such as shooting someone while still knowing that the action is wrong, they would be held criminally responsible. This is because, although the individual was unable to control their impulses, they remained conscious of the wrongfulness of their conduct.

● DURHAM RULE: According to the Durham Rule, a person will not be responsible for criminal liability if the act done by him was because of the mental defect or mental disease. It is also known as ‘product test’. Durham Rule originated from the 1954 case of Durham v. United States12. Monte Durham was arrested for housebreaking. He had a history of treatment of mental illness and crimes. According to some hospital records, he was cured but retained a psychopathic personality. On the basis of the reports, the judges found him guilty without considering the defect he had at the time of commission of act. Later, he appealed to the United States Court of Appeals. IN INDIA Section 84 of the Indian Penal Code 186013 (now Section 22 of Bharatiya Nyaya Sanhita14) deals with the concept of ‘Insanity’.

It states as: “Nothing is an offence which is done by person who, at the time of doing it, by reason of unsoundness of mind, is capable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law. ”15 Insanity is described into four types i. e.

12 Durham v. United States, 214 F.2d 862 (D.C. Cir. 1954).

13 Indian penal code § 84 (Universal’s Lexis Nexis 1860).

14Bharatiya nyaya sanhita § 22 (Universal's Lexis Nexis 2023). 15Indian penal code § 84 (Universal Lexis Nexis 1860).

● Idiot: The one who remains in the state of unsoundness 24*7. ● Lunatic: The person who gets the attacks of insanity in intervals. ● Insane by disease: One who is mentally sick due to some kind of other disease or injury which affected his mind. ● Drunkenness: The one who is not in the proper state of mind because of excessive alcohol consumption. On the basis of these four types, the person is given defense accordingly. According to the law, drunkenness is not a defense unless and until certain exceptions are there. However, not all mental disorders can claim this defense. This defense is only applicable to the ‘LEGAL INSANITY’ and not ‘MEDICAL INSANITY. 16’ A person of medical insanity must also fall in the category of legal insanity to get the defense of section 84(section 22 of Bharatiya Nyaya Sanhita). LANDMARK JUDGEMENTS In R v.

Clarke17, the accused person claims that she was depressed and absent minded when she committed the offence of theft. Later, when she appealed to the court for the defense of insanity, it was found out that she was suffering from deficiency of sugar which caused her diabetic depression. She was given the benefit by the court stating that she didn’t know the nature of act and was in the no intention of committing the crime. In the case of R v. Quick18, the court convicted the accused and stated that mere medical insanity does not approves for the defense of legal insanity. A nurse was charged for assaulting a patient. She was suffering from automatism and asked for the defense. This appeal was the ground for establishing the concept of legal insanity. When a plea of insanity is successful, the individual is not held criminally liable for their actions.

However, to prevent any further issues and ensure public safety, the court typically imposes a sentence focused on the individual's treatment and care. This usually involves 16Math SB et al. , Insanity Defense: Past, Present, and Future. , 37 Indian J Psychol Med 381-387 (2015).

17 R v. Clarke, 1 ALL ERR 219 (1972).

18 R v. Quick, QB 910 (1973)

placement in a mental health facility or other appropriate treatment program rather than a traditional prison sentence. The sentence is given under Section 5 of the Criminal Procedure Insanity Act 196419. The sentence depends on the seriousness of the offence. The hospital orders are passed by the courts according to Mental Health Act, 1983 [section 37]20.The person can also get discharge depending upon the conditions.

CONCLUSION

After examining the relationship between mental health and criminal behavior, it is clear that a significant connection exists and should be taken seriously. Addressing mental health issues is crucial for both individual and public safety. People who exhibit severe mental health problems need proper care to prevent potential criminal actions and protect society. The legal defense of insanity is a reasonable and useful approach. It acknowledges that individuals who cannot understand the nature or wrongfulness of their actions due to mental illness should be treated differently from those who are fully aware of their behavior. This defense ensures a fairer justice system by providing appropriate care and treatment for those with severe mental health issues while still considering public safety.

This defense completely justifies the Latin expression ‘actus non facit reum nisi mens sit rea21’, which means an act does not make a man guilty of a crime unless his mind is guilty. However, the insanity defense is sometimes viewed as a way to evade criminal responsibility, which can lead to potential misuse. To address this concern, courts must implement careful procedures and maintain heightened vigilance during trials to prevent any exploitation of this defense. 19Criminal procedure insanity act § 5 (Universal Lexis Nexis 1964). 20Mental health act, § 37 (Universal Lexis Nexis 1983).

21 Jonathan Law & Elizabeth A Martin, A Dictionary of Law 5 (7th ed. 2009).