The relationship between crime and psychiatry
Lindsay D.G. Thomson, Louise Robinson, in Companion to Psychiatric Studies (Eighth Edition), 2010

Traditional view
Criminal behaviour, particularly violence, by the mentally ill has become a major public issue in the Western world. In the context of an increasing crime rate the public has identified the mentally ill as a significant contributory factor (Appleby & Wessely 1988, Levey & Howells 1995). The UK government has responded by emphasising public protection as paramount in its mental health policies. The question ‘how criminal are people with psychiatric disorder?’ can never be answered with certainty. As a proportion of all psychiatric admissions, the number of patients admitted compulsorily as a consequence of an offence is tiny. In 2003/04 there were 1300 hospital admissions in England and Wales under Part III (the criminal provisions) of the Mental Health Act 1983; this represents approximately 5% of all compulsory admissions to hospitals (Department of Health 2005).
Early research in this area concentrated on arrest rates in former psychiatric patients. These were shown to be minimally higher than those of the general population, or only higher for certain offences. However, when arrest rates of former mental hospital patients were compared with samples matched for demographic variables, the differences disappeared (Monahan & Steadman 1983). Thus for years a somewhat sanguine view of the relation between mental illness and violent offending prevailed. It was held that the well-established factors associated with offending, such as poverty, criminality in the family, poor parenting, school failure, and hyperactivity and antisocial behaviour in childhood, were powerful factors that overshadowed any effect due to mental illness (West 1988).