Persons with intellectual disabilities in the criminal justice system: review of issues.

Although the vast majority of individuals with intellectual disabilities (ID) are law-abiding citizens, there is a small percentage with offending behaviour that is considered antisocial, socially inappropriate, or defined as illegal. It has long been recognised that individuals with ID or mental-health needs who break the law should be dealt with differently from the general population. There have been an increasing number of empirical studies in this area; however, these have been plagued by various definitional and methodological issues. Prevalence estimates of offenders with ID are complicated by diagnostic variations and inconsistencies in the criminal justice process. International studies have shown a large range, from 2% to 40%, depending on methodological approaches. The following review will highlight the salient issues including prevalence of offending, characteristics of offenders, vulnerabilities within the legal system, assessment, and a brief overview of intervention and treatment approaches.