Since people with intellectual and developmental disabilities (I/DD) or mental illness are overrepresented in the criminal justice system as victims, witnesses, suspects, and defendants, this guide provides prosecutors with an overview of useful information needed in developing prosecutorial strategies when a case involves persons who have I/DD or mental illness.
Instead of being a comprehensive, in-depth review of the many practical, medical, and legal issues associated with the prevalence in the criminal justice system of those with mental illness or I/DD, this paper introduces a series of complex issues and concepts related to this issue. Part 1 presents an overview of I/DD and mental illness, along with the legal obligations involved when interacting with people who have mental illness or I/DD. Part 2 presents practical approaches for prosecutors in interacting effectively with these populations that include victims, witnesses, or defendants. Some of the issues addressed in Part 2 are interactions with victims and witnesses with I/DD or mental illness, misconceptions and discomfort common in such interactions, interviewing such victims and witnesses, and special considerations for defendants with I/DD or mental illness. The latter topic addresses the issues of competency, customized dispositions, and diversion to mental health court. Part 3 of this paper provides examples of programs that prosecutors have either created or in which they have participated in their professional involvement in cases that include persons with I/DD or mental illness. The programs reviewed include the Rockland County (New York) District Attorney’s Office Intellectual and Developmental Disabilities Alternative to Incarceration Program, along with the New York State Attorney General’s Office Training on I/DD, Mental Illness, and Police Mental Health Collaborations.