摘要:Burchell explains that mental illness may deprive persons of the capacity to appreciate the unlawfulness of their conduct. It may also deprive them of the capacity to control their conduct. Persons who suffers from a mental illness that has such an effect is said (in legal terms) not to be accountable due to their mental illness. The mentally ill, however, are a distinct subgroup within the penal system. The underlying premise of the defence of mental illness is that persons with mental illness are the victims of an affliction that causes them to behave in an abnormal manner due to their mental illness. They cannot be blamed for their conduct while afflicted by the illness as they lack criminal capacity, or their capacity is diminished. The test for capacity is entirely subjective, relating for example to the capacity of the particular accused person who is alleged to be mentally ill. This note discusses the concept of forensic psychiatry, which is relevant with regard to the defence of mental illness; the concept of mental illness; the defence of mental illness; and how mental illness is interpreted in criminal cases. A conclusion is then drawn to summarise the findings.