Forensic assessment of mental impairment

I’m Dr. Danny Sullivan, I’m the executive director of clinical services at Forensic, which is the Victorian Institute of Forensic Mental Health. I’m a consultant forensic psychiatrist by training. I’m going to speak now of mental impairment, which is also known as insanity, in many jurisdictions. Mental impairment and insanity are legal terms, not medical terms, but they are terms which the law uses to convert a mental disorder into a form of mental experience, which is of relevance in the criminal justice process. In Australia, in Victoria, we use the term mental impairment. But almost all of these definitions hail from 19th century British definitions, definitions which really have only changed marginally in the words used to describe them.

And in general terms, they rely upon firstly, that the person has a mental illness of a particular form. The original words used were a disease of the mind. And that is important because it’s not simply a reflection of personality disorder or a variable experience of the way that one interacts with the world, it must be a defined mental illness. In basis of fact, most of these will be psychotic illnesses such as schizophrenia. But there may be some other conditions which also make that diagnosis, that definition of a disease of the mind.

Most of the criteria for a mental impairment or insanity defense firstly ask that because of the disease of the mind, that is, there is a causal association, that the person is unable to reason about the wrongfulness of their conduct. That is because of delusions or hallucinations influencing their behaviour, the way in which they have acted was not based upon a rational and reasonable apportionment of the facts or an understanding of what was going on. Their behaviour was influenced by mental illness and in fact, but for that mental illness, one could argue that the behaviour would not have happened. And that’s an important threshold distinction.

The second part of that test also involves the potential that a person’s disease of the mind caused them to be unaware of the nature or quality of their conduct. That is, they were so mentally unwell at the time that what they thought they were doing was in fact very different. If I’m driving a car at high speed and I run someone over and killed them but at the time, my mental illness made me think that I was taking a spaceship to the moon and I was accelerating out of the stratosphere. Then it may be that I was unaware of the nature and the quality of the conduct because of my mental illness.

That’s an example from real life, but one which shows that that’s a difficult threshold to meet. So in practice, most people are aware of the nature and quality of their conduct and it’s unlikely or it’s unusual for us to find people with severe mental illness, who don’t know the nature and quality of the conduct. However, being able to reason about the wrongfulness of the conduct is an easier threshold to meet. When I’m assessing a person to determine whether or not an insanity defense might be available to them, the questions that I’ll ask will be open questions rather than closed questions. And I’ll be seeking as much as possible, their unadorned narrative of what they recollect happened.

I may prompt them with information from the brief, but what I’m really looking for, is the influence of mental illness upon their behaviour at the time. Was it a delusional belief which motivated them? Were they experiencing auditory hallucinations, commanding them to do something which they felt they could not resist? And was their behaviour inexplicable except for the presence of those symptoms of mental disorder? I’ll also be comparing with the information from the brief of evidence, and I may well be asking questions such as- this person observed that you appeared to be speaking to someone, but there was no one there. Can you tell me what it was that you might have been hearing?

I’ll be asking a range of questions designed to explore that, and I’ll be seeking that they are consistent with the brief of evidence.