Most South Australians who have a mental illness are treated privately and the patient and the treating health care professional discuss and reach agreement concerning the treatment and care services to be provided to the patient.

For a minority of people with a psychiatric condition, their illness can affect their capacity to understand the illness and their capacity to discuss their condition with a treating doctor. Their behaviour may also be self-injurious or dangerous to others. The Mental Health Act 2009 (SA) provides the legal basis for the involuntary treatment and care of this minority of patients. All references in this chapter are to this Act unless otherwise stated.

The Act is designed to protect the autonomy and liberty of the mentally ill and emphasises the need for the least restrictive approach to any treatment. There is also an emphasis on recognising the role of the family and carers in the treatment, the sharing of information and the preparation of Treatment and Care Plans. The aim of the Act is to bring about recovery, as far as possible, whilst retaining freedom, legal rights, dignity and self respect as far as is consistent with the protection of the mentally ill and the community [see Rights of people with a mental illness].

It is generally accepted that involuntary admission to a specialist psychiatric hospital for emergency, short-term or long-term care should be used only where community-based care is judged as insufficient to meet the person's health care needs or where the admission is absolutely necessary to protect the person or other people.