Forensic psychiatry is a sub-branch of psychiatry that is interested in the interface between mental health and the law. This includes involvement in the court and preparing medico-legal reports. Forensic psychiatrists in New Zealand look after patients requiring secure care, such as special patients found insane or unfit to stand trial, those patients in prison requiring mental health treatment and transition care of patients from secure settings into the community. Forensic psychiatrists therefore have an understanding of relevant legislation and its interpretation by the courts in matters of mental illness.

There are two aspects of forensic psychiatry; providing independent medical assessments and treating mentally ill (or those suspected of being mentally ill) offenders.

There is often confusion between those that have deviant behaviours due to antisocial attitudes or development and those that have acted in response to mental illness. This is not always clear at face value, and seemingly “odd” or “bizarre” offences are not necessarily driven by mental illness. However, on occasions a person with mental illness will not be immediately evident to a lay person (or even psychiatrist). The role of the assessing psychiatrist is to assess for mental illness and help explain motivation for offending, in the context of the individual’s developmental, cultural and genetic background.

A forensic psychiatrist may also be able to assist and interpret the findings of psychologists, particularly in risk assessment. Psychiatrists will give a clinical perspective of issues of risk and try to place this in context. Forensic psychiatrists, for example, are commonly asked to assist the court in matters of risk in reports for preventative detention.