The peak age of offending in the UK is 14 years for girls and 17–18 years for boys (Figure 21.1). Studies in inner London have shown that up to one in five boys have at least one conviction by the age of 21. Half the indictable crimes (more serious and eligible for trial by jury) are committed by persons under the age of 21, and 30% of males have been convicted of such an offence by the age of 30. Crime, in general, decreases with age as personality matures, except for a small peak for women aged 40–50, around the menopause. With the falling numbers of those aged 14–15 in the UK, i.e. the peak age of committing crime, there has been a corresponding fall in the rates of certain offences.

Figure 21.1 • Persons found guilty or cautioned for indictable offences in England and Wales.

Sexual differences in offending rates

In the UK, convicted males outnumber females by five to one, although this preponderance is only half of what it was 25 years ago. The excess may be due, among other factors, to the strength of males in general for repetitive violence (females tend to commit only isolated offences of violence), opportunity at work, for example fraud (although this is an area where females are also increasingly being convicted), the psychology of the male as ‘bread winner’ and females being generally more conforming in behaviour. A female offender generally comes from a more damaged background and is otherwise more psychologically and behaviourally disturbed than a male who has committed the same offence. This, in turn, is reflected in the fact that females in prison tend to be more behaviourally and psychiatrically disturbed than their male counterparts. Females are also reported less frequently for crimes, particularly by male police, yet are up to three times more likely to go to prison for their first offence than males.

In the past it was argued that the female equivalent to male delinquency was promiscuity, but evidence suggests that delinquent males are equally likely to be promiscuous. Some offences are by definition more common in women (e.g. those related to prostitution). Economic motives are commonly given as a rationalization for prostitution, although prostitutes as a group show an excess of mental disorder, self-harm, alcohol or drug abuse, physical disorders, personality disorders and bisexuality.

Premenstrual tension and crime

There is evidence that women premenstrually are more likely to offend, be violent in an institution or harm themselves than at other times during the menstrual cycle. Indeed, some women have successfully used premenstrual tension as a defence to a charge of homicide. It is most likely, however, that premenstrual tension is only an exacerbating factor in such individuals, and it does not imply that women in general are overall ‘less responsible’ at that time of the month.

Juvenile delinquency

Delinquency is defined as law-breaking behaviour. Juvenile delinquency usually means such behaviour committed by 10–21-year-olds. The majority of boys under the age of 17 may commit a delinquent act. Up to one in five males in London have a conviction by the age of 21 and half of all indictable crimes (the more serious offences eligible for trial by jury) are committed by individuals under 21. Five males are convicted for every one female. Recidivism (chronic offending) is associated with an earlier age at first offence and with both loss of life experience and institutionalization due to repeated custodial sentences.

Aetiology

This is multifactorial and is not associated with an established psychiatric disorder. Some such individuals do have personality disorders but opportunity may be more important. For those with personality disorders, the aetiology of their offending is likely to be that of their personality disorder. There is evidence that adult criminality may have an inherited genetic predisposition, especially for acquisitive crime, but this is not definitely so for juvenile delinquency.

Sociological theories include delinquent subcultures and associated peer pressure, differential association and social protest theories of the ‘have nots’. Differences in juvenile delinquency rates have also been related to residence in large towns and even particular bad schools. There is also evidence of labelling effects, i.e. those labelled as delinquent by conviction in court are more likely to continue with such behaviour than if they are not apprehended and convicted.

Individual developmental factors

Studies of children with conduct disorder show that 28% grow up to be psychopathic adults, compared to 4% of those with neurotic disorder and 2% of controls.

The factors summarized in Figure 21.2, if present, are associated with the development of delinquency. If three of these five factors are present, there is a 40% chance of the individual showing delinquent behaviour during adolescence. Also, if troublesomeness at school is noted there is a 50% chance of later showing delinquent behaviour.

Figure 21.2 • Factors associated with the development of delinquency.

Prevention and management

Many of the factors associated with juvenile delinquency are present before birth. It might therefore be countered, for instance, by reducing family size, increasing family income to counter poverty, and countering low intelligence by special attention and remedial education. Individual counselling to improve self-esteem and counter feelings of resentment may help suitable individuals, particularly those who are of high intelligence and show good motivation, but a paternalistic, strict regime tends to be more helpful than a psychodynamically based one for those who are immature and of low intelligence.

Juvenile delinquency may be ameliorated by a good relationship with one parent or, in its absence, a counsellor, by improved emotional harmony in the home and a good experience in school, together with a good peer group. Successful employment and a good relationship/marriage also improve the prognosis as regards adult criminality.

Prognosis

By 19 years of age, half will have stopped their delinquent behaviour. The half who will continue are more likely to be abusing alcohol and drugs, and to gamble, to smoke and to be more sexually promiscuous. Delinquency in teenagers is also associated with criminality in adult life. The best predictor of future criminality remains the extent of previous delinquency, although offending usually ceases in the early 20s.

More recently, a 32-year follow-up of a birth cohort of 1000 New Zealanders has differentiated, apart from adult onset offenders and discontinuous offenders, life course persistent offenders and adolescence limited offenders and the implications for treatment, which is shown in Table 21.1.

Table 21.1 Dunedin Multidisciplinary Health and Development Study 32-year follow-up of birth cohort of 1000 New Zealanders

(A) Life course persistent offenders
Rare, small numbers but responsible for half crime rate
Neurodevelopment problems ↓ Temperament difficulties ↓ Disruptive behaviour ↓ Social learning poor ↓ Personality disorder, particularly antisocial personality disorder which is present in 15–25% ↓ Serious violence	Disrupted attachments Ineffective discipline Delinquent peer influences, truanting, etc.
Victimisation of partners and children
Poor physical, sexual and psychiatric health (especially depression)
Substance dependence (opiates) and alcoholism
More traumatic injuries
Management
Require early childhood interventions in family, but as a chronic cumulative condition requires lifelong interventions
(B) Adolescent limited offenders
Common
Good neurodevelopment and also social and academic skills
Maturation gap in period 15–25 years
Extrovert, sensation seeking and risk taking
Prognosis better if good partner and job
Requires individual treatment, e.g. cognitive behavioural skills training during teen years to counteract peer influence (group treatments facilitate deviant peer networks)
Parent management training and education useful

Mentally abnormal offenders

It has been estimated that 1–3% of all offenders and up to one-third of those in prison suffer from a mental abnormality. Other estimates are even higher. Most suffer from personality disorder/psychopathy and/or alcohol and drug abuse or dependency. Nevertheless, there is an overrepresentation in prison of those with learning disabilities, and both functional and organic mental illnesses. Imprisonment may, of course, precipitate mental illness. In the UK men outnumber women in prison by 30 to one, but female prisoners have more mental and physical disorders.

Mentally abnormal offenders have usually committed petty and minor offences. In fact, it is not certain that the mentally disordered break the law more often. Both mental illness and law-breaking are common. Up to 40% of ordinary psychiatric hospital admissions may follow threatened or actual aggression, but in most of these cases it is usually considered pointless for such individuals to be charged with their offences. When assessing offenders, it is important to bear in mind that they may become mentally ill before, or after an offence due to being in custody or to fear of the likely consequences of the offending.

After committing an offence, a mentally abnormal individual may be arrested and detained in hospital under the civil provisions of that country’s Mental Health Act, or be cautioned by police, or charged. An individual must normally be charged within three days of arrest in the UK. If charged, the individual may be remanded on bail or in custody (e.g. in prison) until the court case is heard.

Forensic psychiatric assessments

Referrals to psychiatrists may be made by the court itself, the probation service and/or defence solicitors. Custom in England and Wales demands that all individuals charged with murder have reports from two psychiatrists prepared on them.

Psychiatrists are expected to assess whether an individual is fit to plead and stand trial, whether mental disorder is present, the individual’s level of mental responsibility, detainability under the relevant Mental Health Act (e.g. Sections 37 and 41 of the Mental Health Act 1983 in England and Wales) and to arrange any treatment recommended, on either an in- or an outpatient basis as required. Psychiatrists are also expected to give an opinion as to the degree of dangerousness of an offender, as far as they are able.

Areas to be considered in a forensic psychiatric assessment are shown in Table 21.2.

Table 21.2 A forensic psychiatric assessment

1. Full history and mental state of patient, including fantasies and impulses to offend

2. Objective account of offence, e.g. from arresting police officer or from statements (depositions) in Crown Court cases

3. Objective accounts of past offences, if any, e.g. obtain list of previous convictions

4. Additional information gathering, e.g. interviews with informants such as relatives, reading a social enquiry report from a probation officer, if prepared

5. Review of previous psychiatric records, e.g. to ascertain relationship of mental disorder to previous behaviour and response to psychiatric treatment and need for security

To rely solely on an offender’s account may lead to an underestimate of the severity of the circumstances of the offence. For example, a paranoid psychotic patient may complain of being threatened when, in fact, the victim plausibly states that the offence was unprovoked. With incomplete information about previous convictions, a psychiatrist runs the risk of being discredited in court.

Table 21.3 outlines areas to be covered in a clinical forensic psychiatric risk assessment and management plan.

Table 21.3 Clinical risk assessment and risk management planning

The aim is to get an understanding of the risk from a detailed historical longitudinal overview, obtaining information not only from the patient, who may minimize his past history, but also from informants. Ideally it should not be a ‘one-off’ single interview assessment.

Reconstruct in detail what happened at time of offence or behaviour causing concern

Independent information from statements of victims or witnesses or police records should be obtained where available. Don’t rely on what the offender tells you or the legal offence category, e.g. arson may be of wastepaper bin in a busy ward, or with intent to kill. Possession of an offensive weapon may have been prelude to homicide.

N.B. Offence = offender × victim × circumstances.

RISK FACTORS FOR VIOLENCE

Demographic factors

Male

Young age

Socially disadvantaged neighbourhoods

Lack of social support

Employment problems

Criminal peer group

Background history

Childhood maltreatment

History of violence

First violent at young age

History of childhood conduct disorder

History of non-violent criminality

Executive dysfunction

Non-compliance with treatment

Psychological and psychosocial factors

Criminal/violent attitudes

Command hallucinations

Lack of insight

Current ‘context’

Threats of violence

Interpersonal discord/instability

Availability of weapons

Consider also protective factors

Practical risk assessment (history × mental state × environment) can be supplemented by standardized instruments of risk, including actuarial risk instruments based on static risk factors, e.g. Violence Risk Appraisal Guide (VRAG), and dynamic risk instruments, e.g. HCR-20 (historic, clinical and risk management -20), based on factors that can change or be managed, e.g. symptoms of mental illness and non-compliance. The psychopathy checklist-revised (PCL-R) was devised by Hare and is used to measure the presence and level of psychopathy, and has been proven to be a good predictor of risk. A short version (PCL-SV) can be used in non-forensic populations. The psychopathy checklist has two main factors (personality traits and deviancy of social behaviour). Only one-third of antisocial personality disorders reach checklist criteria for psychopathy on this scale.

In conclusion

Aim to answer how serious is the risk, i.e. its nature and magnitude, is it specific or general, conditional or unconditional, immediate, long term or volatile. Have the individuals or situational risk factors changed? Who might be at risk?

From such a risk assessment, a risk management plan should be developed to modify the risk factors and specify response triggers. This should ideally be agreed with the individual. Is there a need for more frequent follow-up appointments, an urgent care programme approach meeting or admission to hospital, detention under Mental Health Act, physical security, increased observation and/or medication required. If the optimum plan cannot be undertaken, reasons for this should be documented and a back-up plan specified.

Risk assessments and risk management plans should be communicated to others on a ‘need to know’ basis. On occasions, patient confidentiality will need to be breached if there is immediate grave danger to others. Police can often do little unless a specific threat is issued to an individual, whereupon they may warn or charge a subject. Very careful consideration needs to be given before informing potential victims to avoid unnecessary anxiety. Their safety is often best ensured by management of those at risk.

Multifactorial nature of offending

When assessing an offender it is important to bear in mind that no psychiatric disorder is specifically characterized by offending, and it is important to see an offence as being due to a combination of the offender, the victim and the situation/environment (Figure 21.3).

Figure 21.3 • The multifactorial nature of offending.

Outcomes of sentencing

These are given in Table 21.4. In England and Wales an individual charged with an imprisonable offence may be detained in a psychiatric hospital under Section 37 of the Mental Health Act 1983 (a six-month renewable treatment order). A Section 41 Restriction Order may be added by a Crown Court. This requires Ministry of Justice authorization for leave, transfer or conditional or absolute discharge of the individual from hospital, i.e. it removes the final decision from the patient’s consultant psychiatrist and responsible clinician. The order is made ‘to protect the public from serious harm’ and allows for conditional discharge subject to conditions such as place of residence and compliance with psychiatric treatment.

Table 21.4 Outcome of sentencing of mentally abnormal offenders

• The law takes its course, e.g. a fine, prison

• Conditional or absolute discharge, possibly with voluntary psychiatric treatment

• Community Rehabilitation (old Probation) Order, with or without condition of psychiatric treatment

• Detention under the Mental Health Act (e.g. under Section 37 with or without a Section 41 Restriction Order under the Mental Health Act 1983 of England and Wales)

Under English law a depressed shoplifter would be found guilty, but might be placed on a Community Rehabilitation (the old Probation) Order with a condition of psychiatric outpatient treatment. An individual suffering from schizophrenia who smashed shop windows would be found guilty of criminal damage and might then be admitted to a psychiatric hospital under a hospital order (e.g. Section 37 of the Mental Health Act 1983 in England and Wales). In cases where, for instance, an individual with schizophrenia committed a dangerous offence, a Section 41 Restriction Order (to protect the public from serious harm) may be added by a Crown Court to a Section 37 Hospital Order. Under Section 41, a patient may not go on leave or be transferred without Ministry of Justice agreement but may be conditionally discharged with specified conditions with, for example,place of residence and compliance with psychiatric supervision and treatment. Breach of such conditions could lead to recall to hospital.

In some countries other than the UK mentally abnormal offenders are not considered legally guilty; thus, they do not have a conviction recorded against them and are merely ordered to be detained in hospital for treatment. Under UK law, alcohol and drug dependence are not grounds for detention under the Mental Health Act, although again this does not always pertain in other countries.

The courts

Doctors, whatever their specialty, are likely to have to attend court at some time in their careers if only to give evidence to a coroner’s court or regarding personal injuries.

Over 98% of all criminal prosecutions in England and Wales are dealt with by Magistrates’ Courts. Three magistrates usually preside. More serious indictable offences, which can be heard in front of a jury, are dealt with by a Crown Court, such as the Central Criminal Court, Old Bailey. Appeals can thereafter be made to the Criminal Appeal Court and then subsequently to the Supreme Court of the United Kingdom. Cases can thereafter be taken to the European Court of Justice. A juvenile court is composed of a special panel of three magistrates, one of whom is usually a woman. It deals with offences committed by children and young persons. In these courts the defendant’s name must not be disclosed by newspapers and other media without the court’s permission.

The United Kingdom system of law is adversarial, and, if called to give evidence, for example by the defendant’s legal advisors, a witness will initially undergo examination-in-chief by them, followed by cross-examination, in this case by the prosecution, and then a re-examination. It is important as a doctor not to overstate one’s professional views. One should clearly indicate the limits of expert opinion and in what areas one cannot comment.

In most cases it will be sufficient for a psychiatrist to give an opinion to the court in a report. Oral evidence is usually only requested when there is a dispute regarding the medical evidence, such as in cases of homicide where a disputed psychiatric defence has been put forward (that of diminished responsibility) in order to reduce the charge to manslaughter, or where oral evidence is legally required, for example in supporting an individual being made subject to restrictions under Section 41 of the Mental Health Act 1983 of England and Wales.

Association of particular mental disorders with offending

Remember offending is not a primary characteristic of any mental disorder and when considering an offence, consider not only the offender but also the victim and the circumstances. However, nearly all mental disorders may sometimes be associated with criminal offending (Figure 21.4).

Figure 21.4 • Mental disorders associated with criminal offending.

Organic mental disorders

The onset of minor offending such as shoplifting, minor sex offences and fraud at a late age may be due to dementia (e.g. Alzheimer’s disease) owing to its reduction of intellectual functioning, judgement and normal inhibitions in social behaviour. The elderly, in general, often show coarsening of their personality characteristics and disinhibition with increasing age.

Brain damage from head injuries, even in the absence of significant cognitive impairment, may produce a profound alteration in personality resulting in excessive aggression, for example to a spouse, who may then find it impossible to continue to live with the individual. Brain damage also reduces alcohol tolerance, which in turn may predispose to further head injuries.

Huntington’s disease may present in the early stages with psychopathic behaviour.

The association of epilepsy with offending will be discussed in detail later.

Schizophrenia and delusional disorders

Most individuals who suffer from schizophrenia are not convicted of criminal offences, but, overall, schizophrenia is overrepresented among offenders, particularly compared to affective psychosis. Most convictions are for minor offences and are secondary to the associated deterioration in their personality and social functioning, rather than arising from delusions and hallucinations. Schizophrenia, especially paranoid schizophrenia, can, on occasion, lead to dangerous offending and may result in planned assaults, including homicide, without apparent motive.

Antisocial behaviour is occasionally also seen in the prodromal phase of schizophrenia, when the clinical picture may be referred to as ‘pseudopsychopathic schizophrenia’. Schizophrenia may otherwise distort perception, judgement and voluntary control of actions. Matricide (the killing of one’s mother) is frequently, but not invariably, associated with schizophrenia.

Morbid delusional sexual jealousy (Othello’s syndrome) not infrequently leads to severe aggression towards, and the killing of, a sexual partner about whom delusions of sexual infidelity are held, and this will be discussed in detail later.

Querulous paranoia (litigious paranoia or morbid querulousness) leads to a profound sense of being wronged and a desire to seek redress through the courts.

Mood (affective) disorders

Overall, those with mood disorders are underrepresented in forensic psychiatric populations. Depressive disorder is more generally associated with the risk of suicide, but is, on occasion, associated with homicide, for example the ‘altruistic’ homicide of a family where the individual feels the family may be better off out of this ‘wicked’ world. Homicides associated with depressive disorder are more likely to occur in the mornings and usually involve family members. Seven per cent of individuals suspected of committing homicide commit suicide, with a larger percentage trying, although this predominantly reflects the psychological difficulty of living with having committed such an offence. Shoplifting may also be associated with depression, particularly in middle-aged females of previously good record who may shoplift as a cry for help to bring attention to their mental state.

Hypomania or manic episodes are often associated with disinhibited behaviour, irritability and intolerance, and increased sexual drive. This may lead to convictions for breach of the peace, road traffic offences, impulsive violence and sexual offending such as rape. Such patients spend money excessively, often due to their belief that they will soon make this up, but this can also lead to fraud.

Disorders of adult personality

These are common among offenders but there is no clear cut-off between psychiatrically ‘normal’ individuals who offend and those with personality disorders. Some individuals are given a diagnosis of personality disorder on the basis of the circular argument that they have a personality disorder because they have offended. However, it is possible to contrast psychopathic offending, which is impulsive and unplanned, with more organized planned criminality with co-defendants. Those with personality disorder who offend have frequently abused alcohol or drugs, or are dependent on them, and often have chronic neurotic and stress-related disorders as well.

Learning disabilities (mental retardation)

Those with learning disabilities are three to four times overrepresented among offenders and even higher among violent offenders. This may be because they lack understanding of the nature of their behaviour and its legal consequences, are more suggestible and are easier to catch. Learning disabilities may also lead to feelings of frustration, which in turn may lead to violence and even homicide. Also, in panic or frustration, they may commit arson and also sexual offences that relate to their difficulty initiating and sustaining interpersonal and sexual relationships.

Mental abnormality as a defence in court

• In the UK most mentally abnormal offenders stand trial. If found guilty they are convicted, but medical evidence is given in mitigation to alter the sentencing of the court, e.g. a hospital treatment order may be recommended instead of a custodial sentence.

• Fitness to plead refers to the time of the trial, not the offence.

• Not guilty by reason of insanity (the special verdict) refers to the time of the offence. The grounds (McNaughten Rules) are that by reason of such defect of the mind the subject did not know the nature or quality of the act, or did not know that what he was doing was wrong (forbidden by law).

• Diminished responsibility (Homicide Act 1957) is only a defence to a charge of murder, which carries a mandatory life sentence. It results in a reduction of the charge to manslaughter, which allows discretionary sentencing, including a hospital order.

• Infanticide is the unlawful killing of a child of less than one year by its mother at a time when the balance of her mind was disturbed due to giving birth or from lactation.

Criminal responsibility

This is a legal concept and begins at eight years of age in Scotland but at 10 years of age in England and Wales. It remains partial (Doli Incapax) until 14 years of age. Individuals can, of course, commit serious offences before this age, but in the UK they will not be held legally responsible and cannot be convicted, although they may be placed on a social services care order and held in a secure children’s home. After the age of 14 an individual is considered legally responsible for his actions unless they were due to:

• a mistake

• an accident

• duress

• necessity, e.g. self-defence

• responsibility being affected by mental disorder.

It is questionable how good psychiatrists are in judging responsibility, as opposed to diagnosing mental disorder.

Some offences require specific guilty intent (mens rea) (i.e. specific intent), as well as an unlawful act (actus rea), e.g. murder, rape, arson. Other offences do not require proof of guilty intent, e.g. motoring offences (i.e. basic or non-specific intent). Certain mental states interfere with the patient’s intention (mens rea) and may be defences in law to the actus rea.

Insanity has always been regarded as a defence in English law. A judge in King Alfred’s time was hung for having ordered the hanging of an insane man. By the early 18th century, for insanity to be a defence in law it had to be such as to cause the subject to be like a wild beast – devoid of all reason and memory. However, in 1780 a soldier was acquitted of murder because he was found to be suffering from a delusion about the victim as a result of insanity.

Following an offence, an individual may be detained under a Civil Section of Mental Health Act 1983 (e.g. Sections 2, 3, 4, 136), or cautioned by police, or charged. If charged, the individual may be remanded on bail or in custody (e.g. in prison) until the court case.

Mental abnormality as a defence in court

In most cases the offender stands his trial. If found guilty, or if he pleads guilty, he then presents his medical evidence in mitigation to alter the sentencing of the court, e.g. instead of a custodial sentence, the individual may be placed on a community rehabilitation (old probation) order with or without a condition of in- or outpatient psychiatric treatment or be detained in hospital under Section 37 ± Section 41 of the Mental Health Act 1983. In other countries such mentally abnormal offenders are not legally convicted.

In certain uncommon cases the offender offers evidence of his mental disturbance either:

(a) to excuse his being tried (not fit to plead), or

(b) to agree to having done the act but not to have been fully responsible at the time (insane or diminished responsibility or automatism or infanticide).

Thus, in these cases the psychiatric evidence is presented as part of the arguments to the court and is heard before conviction.

Criminal Procedure (Insanity and Unfitness to Plead) Act 1991

(a) Unfit to plead

A mentally disordered offender may plead that he is unfit to plead (under ‘disability’ in relation to trial). This refers to the time of trial.

He would have to prove, using medical evidence, in a Crown Court hearing that he was not fit to do at least one of the following (based on the original test used in 1836 in R. v. Pritchard):

(1) instruct counsel (‘so as to make a proper defence’)

(2) appreciate the significance of pleading

(3) challenge a juror

(4) examine a witness

(5) understand and follow the evidence of Court procedure.

N.B. The defendant does not have to be fit to give evidence himself. There are current proposals to make this a more specific decision making capacity-based defence i.e. dependent on the ability to understand, remember and use relevant information to make, and to be able to tell their lawyer, their decisions.

If raised by the judge or the prosecution, this must be proved beyond reasonable doubt, but if raised by the defence, this only has to be proved on the balance of probabilities. This is a very rare plea and is only likely to be successful in cases such as severe mental impairment or for patients who are extremely paranoid, e.g. about the court or their legal representatives. In psychotic patients, unfitness to plead is significantly related to thought disorder and delusional thinking. Physical illness, e.g. pneumonia, may also result in unfitness to plead and stand trial.

If found unfit to plead, a decision for a Crown Court judge since the Domestic, Violence, Crime and Victims Act 2004, there is a provision for a trial of the facts. If found unfit to plead, this results in discretionary sentencing, including detention in hospital, a guardianship order, a supervision and treatment order or absolute discharge.

Historically the concept originates from dealing with deaf mutes. In medieval times defendants were pressed under weights to give a plea, without which they could not be convicted, executed or their property given to the Exchequer. Hence, the phrase ‘press for an answer’.

In Scotland, individuals are found unfit to plead more commonly, including in cases where in England they would be convicted and detained under a Section 37 hospital order. Fitness to plead is also often a major issue in the USA where the term ‘competency’ is used.

(b) Not guilty by reason of insanity (‘special verdict’) (insanity defence) (McNaughton rules)

Historically, this defence arose from the case of McNaughton in 1843. McNaughton, believing himself to be poisoned by Whigs, attempted to shoot the Prime Minister Robert Peel, missed (or alternatively misidentified) and shot and killed Peel’s Secretary. Because McNaughton was deluded and insane, he was acquitted but this caused a great deal of argument in the country, which included Queen Victoria (‘Insane he may be, but not guilty he is not’), and the Law Lords were asked to issue guidance for the courts in response to five questions. Their guidance is known as the McNaughton Rules.

In this defence the offender is arguing that he is not guilty (not deserving of punishment) by reason of his insanity. It has to be proven to a court, on the balance of probabilities, that at the time of the offence, the offender laboured under such defect of reason that he met the McNaughten Rules, i.e.

(1) that by reason of such defect from disease of the mind, he did not know the nature or quality of his act (this means the physical nature of the act), or

(2) not know that what he was doing was wrong (forbidden by law)

(3) if an individual was suffering from a delusion, then his actions would be judged by their relationship to the delusion, i.e. if he believed his life to be immediately threatened, then he would be justified in striking out, but not otherwise.

Technically, this plea may be put forward for any offence, but in practice it is usually only put forward for murder or other serious offences. In fact, such a plea is rare.

Evidence from two or more medical practitioners, one approved under Section 12 of the Mental Health Act 1983, is required before return of the verdict ‘Not Guilty by Reason of Insanity’.

Such a verdict implies lack of intent. However, legally, a psychiatrist can only give evidence regarding an individual’s capacity to form intent (a legal concept), not the fact of intent at the time of the offence.

Under the Criminal Procedure Act 1991, if found Not Guilty by Reason of Insanity, the Judge has freedom to decide on the sentencing and disposal of defendant, i.e. discretionary sentencing, including detention in hospital under forensic treatment orders of the Mental Health Act 1983.