insanity.pdf

Insanity and diminished capacity 6
Diagnosing Mental Illness
The criteria which courts apply with respect to responsibility embody a
right-from-wrong-test, which assesses the capacity to act according to the
appropriate insight. The test has biological (i.e. presence
of mental illness) and psychological components (i.e.
impairment of cognitive and/or conative functions) and
a successful defence requires the presence of both.
Case example 8.1 : Depression, murder and criminal responsiblity
Activity 8.5
Discuss the difference between mental
illness and mental defect.
In S v Kavin 1978 (2) SA 731 (W), the accused was charged with murdering his wife, daughter and son. He was
also charged with the attempted murder of another daughter. His defence was that he was suffering from a mental
illness which rendered him non-responsible. He was examined by three psychiatrists who concurred with a
diagnosis of ‘severe reactive depression superimposed on a type of personality disorder displaying immature and
unreflective behaviour’ (p. 734). Two psychiatrists opined that he was able to appreciate the wrongfulness of his
act while a third was uncertain. However, all three concurred that his depressive state rendered him incapable of
acting in accordance with an appreciation of wrongfulness. In this case the accused’s conative functioning was
impaired by a depressive disorder.
Case Exercise
Read the case, along with S v Mahlinza 1967 1 SA 408 (A) (both can be accessed in the collections of law reports
held by most academic libraries). Compare the arguments regarding what constitutes mental illness by focussing
on the expert evidence which was led.
The DSM-IV TR
is a taxonomy of
mental disorders
The law does not provide a definition of mental illness or mental defect
and therefore makes provision for expert testimony to establish this (Van
Oosten, 1990). In order to make a diagnosis of mental illness, the psychologist
uses a variety of tools as part of the clinical assessment process. The clinical
interview provides the psychologist with the opportunity to gather salient
aspects of the accused’s psychosocial history. This history-taking includes
information such as the nature of the symptoms, the level of distress which is
experienced, family history and occupational functioning. In addition the
clinician (psychologist) may make use of measures such as psychological tests
which provide objective information about the accused’s functioning. For
example, personality tests will yield information regarding personality style
and functioning while intelligence tests assess cognitive
functioning. Collateral information (third party
information) may be gathered from significant others so
as to provide additional insight into the accused’s
functioning in various spheres. This information may
be provided by family members, work colleagues or other professionals (such
as general practitioners, psychiatrists and psychologists) whom the accused
has consulted.
An important diagnostic tool which psychologists in South Africa use to
make diagnoses, is the Diagnostic and Statistical Manual of Mental Disorders
(DSM-IV TR) 8(APA, 2000). This system classifies mental disorders in terms
of their diagnostic criteria (symptoms) and provides clinicians with the
information necessary to make diagnoses. For example, to make a diagnosis of
Schizophrenia 4 , the clinician has to establish the presence of psychotic
symptoms, the duration of these symptoms and the degree to which the
4 Schizophrenia is a psychotic disorder characterised by delusions, hallucinations, disorganised speech
and disorganised or catatonic behaviour. (DSM-IV-TR, APA, 2000).
Activity 8.4
What are the various tools which the
psychologist may use to make a diagnosis?
Psychologists
diagnose mental
illness and do
not determine
criminal
responsibility