Introduction

This chapter provides an introduction to and offers an overview of the current evidence base relating to offenders with intellectual disability. In particular, it discusses clinical presentation, risk assessment, clinical interventions and service provision for this group.

Definition and terminology

Although the term ‘mental retardation’ is still used as a diagnostic term in the International Classification of Diseases (ICD-10; World Health Organization, 1992), it is perceived to be offensive to people with intellectual disability and has been replaced in policy, administrative and legislative forums in many countries by ‘intellectual disability’ (Salvador-Carulla et al, 2011). The term mental retardation will be updated to intellectual developmental disorders in the ICD-11 manual currently being revised. Often terminology to describe this group changes according to the context. For example, intellectual disability is still often substituted for learning disabilities in the UK by both services and user groups and is the term used in the Mental Health Act. This chapter will use the term intellectual disability, which is defined as impairments in social and intellectual functioning that occur during the developmental period (Department of Health, 2001).

The Mental Health Act 1983 for England and Wales sets out the law for the assessment and treatment of people with mental disorder and the criteria for compulsory action to be taken where the person is a risk to themselves or others, while safeguarding the individual. This includes civil detention and disposal or transfer to healthcare via the courts as a sentence or pre-sentencing assessment. The Act also legislates on appropriate aftercare, treatment and consent, safeguards, advocacy and appeals. The definition of mental disorder under the Act has been updated and replaced by a wider definition in the 2007 amendments to ‘any disorder or disability of the mind’. This does not include intellectual disability per se. The Act is clear that people with intellectual disability shall not be considered ‘to be suffering from mental disorder’ and therefore cannot be considered for detention for assessment and/or treatment under the Act simply as a result of their intellectual disability, unless the disability is associated with abnormally aggressive or seriously irresponsible conduct.