Psychiatry and Criminal Law

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Psychiatry and Criminal Law

Also related to forensic Psychiatry:

Originally, the term ‘forensic psychiatry’ referred to the interaction between psychiatry and criminal law. However, psychiatry is intricately connected with the law.

Overview of Psychiatry and Criminal Law 

Forensic psychiatry now mostly deals with two types of patient:

  1. Individuals with mental disorders who have broken the law, i.e. mentally disordered offenders;
  2. Individuals with mental disorders who are, or may be, violent.

In most developed countries, forensic psychiatry is a distinct sub specialty of psychiatry, but in some other countries all psychiatrists may be involved in the management of mentally disordered offenders.

There are two UK legal concepts relevant to mentally disordered offenders—the defence of ‘insanity’ and that of ‘diminished responsibility’.

Defence of Insanity:

  • It can be used as a defence against any crime of which the defendant is charged.
  • In order to ‘qualify’ for insanity, the defence must prove not only that the defendant had a disease of the mind at the time of the offence, but also that this led to a defect of reason.
  • This leads to the supposition that the defendant did not know that what he was doing was wrong at the time.
  • The defendant is then acquitted on grounds of insanity.

Diminished Responsibility:

It is a defence that can only be used for a charge of homicide.

If the defence convince the jury that due to their underlying mental illness they were not fully to blame for their crime, the charge may be reduced to manslaughter.

This section provides a brief overview of the links between mental disorders and crime, and the structure of forensic psychiatry.

Patterns of Crime of Psychiatry and Criminal Law

Current patterns of crime:

  • The prevalence and pattern of criminal offending change over time in most countries.
  • Figures for the prevalence of crime must be viewed cautiously as they depend on reporting and upon definitions of crime.
  • Typically, the public perception of the quantity and type of crimes is markedly different from official statistics.
  • The public tend to overestimate both the number of and severity of crimes committed in their neighbourhood.
  • Much criminal behaviour goes unreported; this is especially true of domestic violence.
  • In the UK, crime has been steadily reducing for the past l decline of 5 percent for the period 2008–2009 compared with the previous year.
  • The risk of being a victim of crime in any given year is currently 26 per cent, down from 40 per cent in the mid 1980s.
Risk factors for criminal offending:

This is because most of them are the same for offenders with and without a mental health problem.

They are best considered within the biopsychosocial model & from the table, it is clear that family and social factors are by far the most important risk factors.


  • Male gender
  • Low IQ
  • Age (peak 10–25 years)
  • Genetics: in mono-zygotic twins concordance for committing crime is 80%
  • Ethnicity (Afro-Caribbeans > Caucasians > Asians)
  • Hyperactivity and impulsivity
  • Teenage mother


  • Personality traits: lack of empathy
  • Poor parental supervision and poor attachment
  • Harsh discipline in childhood
  • Aggression, violence, or criminal activity within the family
  • Parental conflict and/or ‘broken homes’
  • Separation from biological parents before 10 years of age


  • Larger family size
  • Lower socioeconomic status
  • Poor housing
  • Unemployment
  • Peer influences: school, neighborhood (especially gang culture)
  • Spouse or partner is an offender
  • Inner-city living
  • Alcohol and substance abuse

Psychiatry and Criminal Law of Disorders and Crime

Mental disorders and crime:

Contrary to public perception, few psychiatric patients break the law, and when they do, it is usually in minor ways.

Although serious violent offences by psychiatric patients receive much publicity, they are infrequent and committed by an extremely small minority of patients.

It is, however, important that doctors are aware of the risk of criminal behaviour amongst those who are mentally ill.

Threats of violence to self or to others should taken seriously, as should the possibility of unintended harm resulting from disinhibited, reckless, or ill-considered behaviour.

There is a small but significant association between mental disorder and violence; 5 percent of violent crimes in the UK are committed by an individual with a severe psychiatric illness.

The prevalence of violent behaviour in those with mental disorders compared with the general population is as follows:

  • Prevalence of violent behaviour in the general population (without mental disorder) is 2 percent.
  • Prevalence in those with a major mental illness is 7 percent.
  • The prevalence in individuals with a substance abuse disorder is 20 percent.

Risk factors for violent behaviour in patients with mental disorders:

Major psychoses (especially if associated with the following):

  • Paranoia (with increased perception of threat to self)
  • Command hallucinations
  • Passivity phenomena
  • Puerperal psychosis—increased risk to the child
  • Delusional disorders (especially delusional jealousy towards a partner)
  • Severe depression (increased risk of infanticide and arson, but not most other crimes)
  • Antisocial, impulsive, or self-centered personality traits (increases risk by 16-fold)
  • Poor impulse control
  • Co-morbid use of alcohol or substances
  • Prior history of conduct disorder
  • Poor insight into illness or behaviour

It is worth noting that whilst excited patients are at high risk of disinhibited behaviour, reckless spending/driving and agitation, violence towards others or property is rare.

It is widely appreciated that mental disorders are massively over-represented amongst the prison population of most countries, and several large meta-analyses have been undertaken.

The prevalence of psychosis and major depression appears to be at least twice as high as in the general population, and the prevalence of personality disorders about 10 times as high.

Although the prison population has been steadily growing in recent decades, the number of mentally disordered offenders detained has been almost static.

Associations between specific psychiatric disorders and types of offence:

It is difficult to directly link specific psychiatric diagnoses with particular offences.

Mental disorders are not like many medical conditions (e.g. appendicitis) in that they rarely have a typical presentation.

There is great clinical heterogeneity and this is represent in the variety of offences that may be committed.

The following provides a brief overview of some associations between crime and particular disorders.

Schizophrenia i.e.:
  • Overall, crime is uncommon and usually minor, however, threats of violence should take seriously.
  • Compared with the general population, there is a two to four fold increase in risk of violence in men with schizophrenia, and a six to eight fold increase in women.
  • The individuals who are violent are often suffering from persecutory delusions, command hallucinations, or passivity phenomenon, typically the patient perceives others to a threat to their safety.
  • Violence is almost always towards family members; stranger attacks are uncommon.
  • Whilst these positive symptoms are risk factors. Additionally; they are outweigh by the increased risks associated with using alcohol and drugs.
Delusional disorders i.e.:
  • Individuals with delusional disorders are significantly over-represent in secure psychiatric hospitals, but uncommonly commit serious crime.
  • The particular conditions that are involve are delusional jealousy, delusions of love, querulous delusions, and misidentification delusions.
  • Sixty percent of those with delusional jealousy are violent towards their partners.
  • Stalking is a particularly interesting condition, which may associate with a delusional disorder.
  • There is an increase risk of homicide (both in the stalker and their victim) associated with stalking.
Mood disorders i.e.:
  • There is a low risk of offending in mood disorders.
  • An association between shoplifting and depression was suggest but systematic review has not confirmed this.
  • Very rarely, patients with severe depression may become violent.
  • Approximately 5 percent of UK homicides are follow by suicide of the perpetrator; in this situation depression is a common finding, although nihilistic delusions as a possible trigger are extremely rare.
  • More often, marital breakdown and other socioeconomic problems are evident.
  • excited patients occasionally commit petty crime due to their exuberant, unpredictable behaviour.
  • Charges such as indecent exposure, disrupting the peace, and minor theft are not uncommon.
  • Violent or serious crimes are rare.
Personality disorders i.e.:
  • The association between personality disorders and all types of crime is much stronger than for mental disorders.
  • Antisocial, overly suspicious, and borderline traits are particularly likely to lead to crime.
  • As previously mentioned, up to two-thirds of prison inmates have a personality disorder, most frequently antisocial personality disorder.
  • The combination of a personality disorder and alcohol/drug misuse increases the risk of offending by 16 times.
  • Official figures from Sweden reported 50 percent of individuals convicted of homicide in 2005 had a diagnosis of a personality disorder.
  • As well as violence, there is also an increase risk of sexual offences.
Alcohol and drug abuse i.e.:
  • Both of these addictions are commonly associated with offending of all types.
  • There is an added risk of driving under the influence, with alcohol playing a role in about 20% of traffic-related deaths.
  • Alcohol is also identify as a factor in over half of interpersonal assaults in England and Wales.
  • Much petty theft, fraud, and other minor crimes are commit to fund drug habits.
Learning disability and autistic spectrum disorders i.e.:
  • These are rarely associate with offending, and when they are it is usually a minor crime by an individual lacking understanding of the legal implications of their actions.

Crimes of Violence of Psychiatry and Criminal Law


  • The rate of homicide varies enormously between countries, but it is clear that only a minority are commit by mentally disordered people.
  • In the UK, there are 500–600 homicides each year, in 80 percent of which the victim is know to the perpetrator.
  • In the USA, the majority are by shooting.
  • Approximately 10 percent of homicides are commit by a person in touch with mental health services, only half of whom have a ‘severe’ mental illness.
  • Of these, one-third have had admissions under the Mental Health Act.
  • Five to ten percent of homicide convictions are reduce to manslaughter due to a plea of diminished responsibility, or acquitted on grounds of insanity.


  • Infanticide is the killing of a child below the age of 12 months by the mother.
  • When the killing is within 24 hours of birth, the baby is usually unwanted, and the mother is often young, distressed, and ill equipped to cope with the child, but not usually suffering from psychiatric disorder.
  • When the killing is more than 24 hours after the birth, the mother usually has a mental disorder, most commonly untreat puerperal psychosis or postnatal depression.
  • About a third of mothers in this second group try to kill themselves after killing the child.

Family Violence:

  • Violence within the home is common but often undetect.
  • It may affect children, the partner, or an older people relative living in the house.
  • Violence is strongly associate with excessive consumption of alcohol.
  • A quarter of women experience domestic violence, which leads to serious injuries (e.g. broken bones) in 10 percent of cases.
  • Wife battering is associated with aggressive personality, alcohol abuse, and sexual jealousy.
  • Marital therapy may attempted to reduce factors provoking the violence, but often alternative safe accommodation has to be found for the woman and any children.

Sexual offences:

  • Generally, A sex offender is an individual whose sexual behaviour contravenes the law.
  • The most frequent offences are indecent exposure, rape, also unlawful intercourse.
  • Most sexual offences are commit by men; additionally the common sexual offence among women is prostitution.
  • Severe mental disorders are rare amongst sex offenders, but personality disorders are over-represented.


  • Most shoplifters act for gain but a minority do so when mentally disordered.
  • Patients with alcoholism, drug dependence, and chronic schizophrenia may shoplift because they lack money, and patients with dementia may forget to pay.
  • Among middle-aged female shoplifters it is common to find family and social difficulties and depression.
  • Arson is setting fire to property, an act that may also endanger life.
  • Most arsonists are male.
  • Usually, there is no obvious motive for the act and many arsonists are referred for a medical opinion.
  • However, few have a psychiatric disorder.

Repeated gambling (pathological gambling):

  • This term is used to describe a condition in which a person has an intense urge to gamble and a preoccupation with thoughts about gambling.
  • Gambling is not, in itself, an offence but large debts can accumulate and may result in stealing or fraud.
  • Some psychiatrists regard this condition as a disorder akin to addiction to alcohol, and offer treatment similar to that use for substance abuse.

The Role of doctors in relation to crime:

  • Assessment of offenders who may have a mental disorder.
  • Advice to the police when they are deciding whether to proceed with charges against mentally disordered offenders.
  • To be fit to plead, a person must able to understand the nature of the charge and the difference between a plea of guilty and a plea of not guilty, instruct lawyers and challenge jurors, and follow evidence presented in court.
  • A person can suffer from severe mental disorder and still fit to plead.
  • A person judged unfit to plead is not try but detained in a hospital until fit to plead, at which time (if it comes) the case is tried.
  • Assessment of responsibility; providing evidence and/ or an opinion as to whether the defence of insanity or diminished responsibility is appropriate.
  • Giving evidence in court, or writing a formal report for the criminal court.
  • Treatment of offenders whilst in custody or prison, in hospital, or in the community.
  • Providing risk assessments of offenders anywhere within the criminal legal system.

Treatment of mentally disordered offenders:

  • The fundamental aspect of treating mentally disorder offenders is that the principles of treatment are the same as for any other patient.
  • However, it may need to undertake in a more secure environment.
  • Forensic psychiatrists tend to treat these patients, be they in prison, a secure psychiatric hospital, or in the community.

The Prison Psychiatrist:

As already outlined earlier in this chapter, a vast proportion of individuals within prisons have psychiatric disorders.

The majority of forensic psychiatrists work in ‘normal’ prisons, and only a few in secure psychiatric hospitals.

There are four main situations in which a psychiatrist may ask to see a prisoner i.e.:

  • To provide a court report before a trial;
  • Assess a patient in prison;
  • Provide treatment for prisoners;
  • To provide a report for the parole board.

Prisoners should assessed as for any other patient, also offered the same range of treatments as would be available in the community.

Secure Psychiatric Hospitals:

Patients may admitted to secure psychiatric hospitals from the courts, prisons, or less secure hospitals.

The majority of mentally disordered offenders are sentence to undertake a prison sentence in the mainstream system or compulsory treatment in the community.

However, when there is a continuing risk to other people of aggression, arson, or sexual offences, treatment is arrange in a unit providing greater security to ensure the protection of society.

There are several parts of the MHA 1983/2007 which provide specific legislation for mentally disordered offenders.

Sections 35 and 36 :
  • They are equivalent to Sections 2 and 3 in civil law, and are use for patients awaiting trial for a serious crime.
  • They are an alternative to sending the patient to prison whilst awaiting trial.
37- Section :
  • It is a treatment order (similar to Section 3) which can use for mentally disordered offenders who have convicted of a serious crime and sentence to imprisonment.
  • After 6 months, the patient may request an MHRT in the usual way, but if the patient is find to have recovered from the mental disorder they transferred to prison rather than discharged home.
41- Section:
  • Patients who pose an extremely high risk to others may have a Section 41 added to their Section 37.
  • This imposes further restrictions, most importantly that only the home secretary can decide that the person can leave hospital.
47- Section:

It allows for prisoners to transferred from a prison to a psychiatric hospital for treatment.

Community Treatment:

As in the rest of psychiatry, treating a mentally disordered offender has two parts:

  1. Managing the acute psychiatric disturbance;
  2. Then rehabilitating the patient to life in the community.

Once a mentally disordered offender is deem fit for discharge from hospital, and has completed their mandatory sentence, it is essential they receive appropriate community follow-up.

This is provide in a similar way to that in the general services, with community psychiatric nurses, social workers, occupational therapists, also many other professionals providing input.

Furthermore, For a patient to be successfully reintroduce into society and to reduce the chance of re offending it must clear that their mental state is appropriate, and that they have the skills require for community living.

This includes help finding somewhere to live, employment, hobbies, financial assistance, also reintegration with family.

All in all, The latter can be extremely difficult, and family therapy plays a vital role.

Frequently Asked Questions

What is Psychiatry and Criminal Law?

The term ‘forensic psychiatry’ referred to the interaction between psychiatry and criminal law. However, psychiatry is intricately connected with the law.

What are the risk factors for criminal offending?

  • Biological
  • Psychological
  • Social

What are the crimes of violence?

  • Homicide
  • Infanticide
  • Family Violence
  • Sexual offences
  • Shoplifting
  • Repeated gambling

Psychiatry, Fourth Edition – Oxford Medical Publications -SRG-by John Geddes, Jonathan Price, Rebecca McKnight / Ch 12. Psychiatry and Criminal Law

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