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For the past two centuries, there has been no change in the understanding and knowledge of people other than autonomy and capacity to choose the right and wrong for criminal liability. The insanity defence has a long history, and is evolved after many tests that have been tried and tested. McNaughton’s rules stressed on “understandability of right and wrong” and “intellectual” rather than a moral or affective definition dominated in its formulation.

Insanity defence is primarily used in criminal prosecutions. It is based on the assumption that at the time of the crime, the defendant was suffering from severe mental illness and therefore, was incapable of appreciating the nature of the crime and differentiating right from wrong behaviour, hence making them not legally accountable for crime. Insanity defence is a legal concept, not a clinical one (medical one). This means that just suffering from a mental disorder is not sufficient to prove insanity. The defendant has the burden of proving the defence of insanity by a “preponderance of the evidence” which is similar to a civil case. It is hard to determine legal insanity, and even harder to successfully defend it in court.


The concept of defence by insanity has existed since ancient Greece and Rome. The first known recognition of insanity as a defence to criminal charges was recorded in a 1581 English legal treatise stating that, “If a madman or a natural fool, or a lunatic in the time of his lunacy” kills someone, they cannot be held accountable. The British courts came up with the “wild beast” test in the 18th Century, in which defendants were not to be convicted if they understood the crime no better than “an infant, a brute, or a wild beast.”

The insanity defence in the court is generally taken as an excuse rather being a justification of facts and the crime. The most important questions that arises with the insanity defence is about the competency at the standing trail. In the requirements of due process of law, an accused cannot stand competent of the trail if he/she is legally incompetent. As directed by the hon’ble Supreme Court of Dusky a person is said to be incompetent if he/she is unable to communicate properly to her attorney about the proceeding of the case. This was directed because the proceeding involves some form of the psychological evaluation process to which an incompetent person cannot withstand. In absence of his psychological involvement and understanding in the status quo. It merely remains a moot rather than a standing trail.

The concept of responsibility connects with our most fundamental convictions about human nature and dignity and everyday experience of guilt and innocence and blame and punishment.[1] Punishing a person, who is not responsible for the crime, is a violation of the basic human rights and fundamental rights under the Constitution of India. It also brings the due process of law, if that person is not in a position to defend himself in the court of law, evoking the principle of natural justice.[2]

The affirmative defence of legal insanity applies to this fundamental principle by excusing those mentally disordered offenders whose disorder deprived them of rational understanding of their conduct at the time of the crime. Hence, it is generally admitted that incapacity to commit crimes exempts the individual from punishment. This is recognized by the legislation of most of the civilized nations. Even in India, Section 84 of Indian Penal Code (IPC) deals with the “act of a person of unsound mind” and discusses insanity defence. However, in the recent past some of the U.S states (such as Montana, Idaho, Kansas, and Utah) have banned insanity defence. This issue has raised a serious debate among medical, psychology and law professionals across the world.

Criminal liability requires proof of three interrelated components as follows:

Commission of the prohibited conduct specified in the offense (Actus Reus)Committed with a particular mental state (Mens Rea)Committed without a legal defence.

The concept of “responsibility” arises with most of the cases involving human conduct and presence of guilt, knowledge of the act and its consequences. A person thoroughly oblivious about its surrounding, or unaware of the distinction between right and wrong, is not the one to punish.

Punishing someone who is not responsible for the crime is a violation of basic human rights and fundamental rights under Constitution of India. It also brings the due process of law, if that person is not in a position to defend himself in the court of law, evoking the principle of natural justice.

The plea of insanity as a defence in criminal cases has a long and fascinating history.

The introduction of “McNaughton’s Rules” in 1843 was a turning point in the history of the insanity defence. In 1843, a wood-turner from Glasgow, Daniel McNaughten shot and killed Edward Drummond mistaking him for Sir Robert Peel. McNaughten believed that he was persecuted by the Tories, and evidence was brought to show that he had been totally deluded on this subject for some time. His state of mind was evident from the beginning when he had to be enticed, and finally tricked, into pleading “not guilty.” After hearing seven medical witnesses testify that he was completely insane, the judge stopped the trial, the jury brought in the special verdict without summing up and without retiring, and Mc Naughten was forcibly committed to the Bethlem Hospital. Five propositions were drawn thereafter, which were called Mc Naughten’s Rules.

A criminal defendant who’s found to have been legally insane when they committed a crime may be found not guilty by reason of insanity. In some cases, the defendant may be found guilty but sentenced to a less severe punishment due to a mental impairment. In states that allow the insanity defence, defendants must prove to the court that they didn’t understand what they were doing; failed to know right from wrong; acted on an uncontrollable impulse; or some variety of these factors.

Below you’ll find basic information and legal issues related to the insanity defence, how courts test for insanity, and differences in state laws and procedures.

Very little research has been done on this topic in India, however, there are few studies on exploring the clinical picture of the patients in prison. A landmark study in the forensic psychiatry of Indian setting occurred in 2011, in which 5024 prisoners were assessed on semi-structured interview schedule reported that 4002 (79.6%) individuals could be diagnosed as having a diagnosis of either mental illness or substance use. After excluding substance abuse, 1389 (27.6%) prisoners still had a diagnosable mental disorder.[3]

Another study from India portray a very gloomy picture of patients in forensic psychiatry settings and advocate for there is a need to streamline the procedure of referral, diagnosis, treatment, and certification.[4] To address this issue of streamlining the process of evaluation of insanity defence and certification, this article focuses on semi-structured assessment in the Indian context based on landmark Supreme Court decisions. In addition, it will also present a model for evaluating a defendant’s mental status examination and briefly discuss the legal standards and procedures for the assessment of insanity defence evaluations.


Through the insanity defence has taken a legal position in the last three centuries it has been into existence for decades. There were various tests used to declare a person legally insane such as the Wild Beast test, The Insane Delusion test, and the test of capacity to distinguish between just and unjust. These three tests laid the foundation for the landmark Mc Naughten rule. This Mc Naughen rule become a remarkable precedent for the law concerning the defence of insanity. Even in India, section 84 of IPC (Indian Penal Code) is solely based on Mc Naughten rules.

Section 84 of IPC Act of person of unsound mind:- “Nothing is an offence which is done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law.”

Section 84 IPC, clearly embodies a fundamental maxim of criminal jurisprudence that is,

(a) “Actus Reus Non Facit Reum Nisi Mens Sit Rea” – an act does not constitute guilt unless done with a guilty intention;

(b) “Furiosi nulla voluntas est” – a person with mental illness has no free will.

Hence, Section 84 of IPC affixes no culpability on persons with mental illness because they can have no rational thinking or the necessary guilty intent.

The insanity defence is neutral concept. There are many beliefs regarding this in the legal world. Some scholars think it is helpful for those who are actually incapable of understanding the difference between just and unjust, on the other hand, there are scholars who believe the defence of insanity is giving an unfair chance to the culprits who act as insane but are actually not.

Depending on the jurisdiction, courts use one or a combination of the following tests for legal insanity:

  • The “Mc Naghten Rule” – Defendant either did not understand what he or she did, or failed to distinguish right from wrong, because of a “disease of mind.”
  • The “Irresistible Impulse” Test – As a result of a mental disease, defendant was unable to control his impulses, which led to a criminal act.
  • The “Durham Rule” – Regardless of clinical diagnosis, defendant’s “mental defect” resulted in a criminal act.
  • The “Model Penal Code” Test for Legal Insanity – Because of a diagnosed mental defect, defendant either failed to understand the criminality of his acts, or was unable to act within the confines of the law.

Most states in the world that recognize legal insanity use either the Mc Naghten Rule (sometimes in combination with the Irresistible Impulse Test) or the Model Penal Code. Only New Hampshire uses the Durham standard.

If you’re wondering whether your case will qualify for an insanity defence, you’ll need to know your state laws and whether they follow the Mc Naghten Rule or the Model Penal Code. You don’t have to do this alone. Start learning more today by contacting a criminal defence attorney in your area to discuss the specific facts of your case.


1. Temporary Insanity:- A condition where a person is insane only periodically or for a specific point of time. Some temporary mental illnesses or insanities include depression, anxiety disorders, schizophrenia, eating disorders and addictive behaviours. There are two possible outcomes in the defence of temporary insanity, one is ‘not guilty because insane’ and the other is ‘guilty but cannot be tried because insane.’

2. Permanent insanity:– A condition where a person is persisting a mental illness continuously. It can be proved from past records and events that had occurred proving that the person is permanently insane and is incapable of understanding the gravity of any situation.


1. It creates an instant atmosphere of guilt.

The case of the insanity defence has a slight difference as compared to others. In such cases, the accused need to confess that he has committed the crime but had no idea about what he has done. He is incapable to differentiate between what is right and what is wrong. Here, the mental state of the accused is may become a supporting or opposing factor for his defence of insanity.

2. It does not allow the death penalty.

An insane person cannot be given the death penalty, although he confesses his crime, he is incapable to understand the gravity of what he has done. Instead, any lenient punishment could be charged to the accused.

3. It can lead to a no-jail term or possible acquittal.

In some instances, where the mental condition of the accused has been proved to the court, he is neither charged with any penalties nor any acquittal. It all depends upon the mental status he is possessed with.


4. It is abolished in some jurisdictions.

It is important to note here that not all the courts accept the plea of insanity in their jurisdiction. It has been abolished at some places, so if any such case arises which is successful in convincing the jury is transferred to such a jurisdiction where this provision is followed.

5. It can lead to increased trial costs.

One of the most important points here is that it increases the trail costs. To prove the insanity the defence will definitely hire a specialist to prove their point to the court. Also, the prosecution will also do the same. In this process, a significant amount of money would be used. And among all these only the least number of cases go successful in taking the defence of indemnity.

6. It can be very difficult to prove.

It is a very big challenge for the defendant to prove the plea of insanity. Mental illness can be proved by having it checked by an expert who as per his knowledge, test and experience gives proof of the actual mental status of the accused. Even after that, it is upon the judges to accept or reject the defence of insanity thus produced. It does not give any guarantee of relief or solution to the accused.

7. It can be misused

The defence of insanity can even be misused to escape from the acquittal or punishment. It is very difficult to examine whether the person was of sound mind or unsound mind at that point in time. In the end, it all depends on how the judge understands the matter and gives his judgment.


Critics argue that some defendants misuse it, effectively faking insanity to win acquittals or less severe convictions. And often the trials involving an insanity defence get the most attention because they involve “crimes that are bizarre within themselves”, said Baltimore defence attorney Cristina Gutierrez, who has defended a dozen such cases in as many years. Some high profile cases of Insanity defence are listed below, where in some cases, the juries agreed, but more often than not, the criminals were found sane enough to know that what they were doing was wrong.


Ted Bundy was attractive, smart, and had a future in politics. He was also one of the most prolific serial killers in U.S history. When he was being tried for the murder of one of his many victims, Kimberly Leach, he and his attorneys decided on an insanity plea, the only defence possible with the amount of evidence the state had against him. It did not work, and on January 24, 1989, Bundy was electrocuted by the state of Florida.

The Case of CD In January 1976, CD stabbed and killed her husband because she believed he was a vampire. She then attempted to stab her eleven-year-old son because she believed he was a werewolf. Sometime before the murder, she had told her husband she was hearing noises of the devil and was being programmed. In March, CD was found to be competent to stand trial and was diagnosed as a schizophrenic, paranoid type in partial remission and She was receiving Stelazine, 15 mg., Artane, 6 mg., and Thorazine, 150 mg., daily. After being found not guilty by reason of insanity in June of 1976, she was adjudged to be in remission and not in need of hospitalization. The final diagnosis was a schizophrenia, paranoid type. At that time it was noted that the defendant’s insight was minimal; although she stated that she knew she needed psychiatric care, CD expressed superficial sorrow for her husband’s death. She was continuing to receive the same medication as before. In July 1976, CD was released to outpatient treatment for six months, which expired without incident.,


The insanity defence is a loophole for the criminals despite of many advantages. They are:-

  • It is the most popular weapon as a defence in this century to escape from any crime.
  • It is almost impossible to prove the mental status of any person at the time of the offence.
  • It is not just concerned with the mental insanity but with the legal insanity.
  • Mere arguments are not enough to decide that the accused deserves the defence, it depends upon the circumstances.
  • The case of insanity defence becomes more complicated as compared to others as it not to prove that the accused has performed the crime or not, rather it is about the accuse confessing his crime and stating that he has no idea about what he has done.

These reasons are making insanity defence a much easier and modern way for criminals to exempt from the crimes they perform intentionally.

Recent data strongly suggest that mentally disabled persons who have committed a crime are significantly more likely to be arrested for criminal behaviour, including violent offenses, after release than are members of the general community.’ Rigorous comparisons of former mental patients who previously committed a crime with others of similar age, sex, and socioeconomic status who had prior criminal histories but no mental hospital admissions have not been made.

We cannot say at this point that the person found not guilty by reason of insanity is more likely to commit a new violent crime than is a sane, but otherwise comparable, exoffender, but there is no evidence that he is any less of a threat to public safety than is his sane peer. In terms of societal protection, there is no reason to treat the person found guilty of violent criminal acts but not responsible by reason of mental disability as any less of a threat than the sane convicted criminal.

If punishment, retribution, or just deserts is our justification for incarceration, the harm done by the insane defendant and the affront to societal norms are no less great than those by the sane defendant acting in the heat of passion, or recklessly, or with criminal negligence. An argument can also be made for abolition of the insanity defence in the name of deterrence. A person found not guilty by reason of insanity and released on psychotropic medication-which reduces his potential for violence-often needs motivation to stay on his medicine. The prospect of incarceration-if the person were to neglect to take the medication, relapse, and commit a new criminal act-might well supply the necessary impetus to stay on medication.

Individuals could be motivated to participate actively in psychotherapy, if that were prescribed. Finally, for that rare but possible individual who would feign insanity in hopes of quick release, the rewards of a successful insanity defence would be greatly reduced.


[1] Abolition of the insanity defence violates due process. Morse SJ, Bonnie RJ J Am Acad Psychiatry Law. 2013; 41(4):488-95.

[2] Gostin LO, Larry OG. A Human Condition: The law relating to mentally Abnormal Offenders. Vol. 2. MIND; 1977.

[3] Math SB, Murthy P, Parthasarathy R, Naveen Kumar C, Madhusudhan S. Mental Health and Substance Use Problems in Prisons. The Bangalore Prison Mental Health Study: Local Lessons for National Action. Publication, National Institute of Mental Health and Neuro Sciences, Bangalore. 2011. [Last accessed on 2014 Nov 15]

[4] Profile of male forensic psychiatric inpatients in South India. Kumar D, Viswanath B, Sebestian A, Holla B, Konduru R, Chandrashekar CR, Math SB Int J Soc Psychiatry. 2014 Feb; 60(1):55-62.

Author Details: Gauri Khera, (2nd year student of B.A. LL.B. (Hons.) at Chander Prabhu Jain College of Higher Studies and School of Law)

The views of the author are personal only.

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