Expert Witness and Insanity
| DOI | 10.1177/000486587400700307 |
| Published date | 01 September 1974 |
| Date | 01 September 1974 |
184
A
ivr
N ZJ (" (1974) 7
Case
Report
I
Expert Witness
and
Insanity
Washington
vU.S.A.
(rExcerpt),
No. 20,232
U.S Court of
Appeals,
District
of Columbia
CIrcuit.
" 390 F 2d 444 at 457
c:====:===============..,
THE
subject
matter
of
this
appeal
is
of
no
moment,
and the
excerpt
is
publish-
ed
only
because
of
its
statement
regarding
the
expert
witness
and the
defence
of
insanity.
Although
the
"instruction"
to the
expert
witness
relates
to the
Durham
Rule
-
note
the
concept
of
·
'product"
-
nevertheless
it
is
felt
that
the
comments
of
the
court
are
of
general
interest
and
have
applicability
for
the
expert
witness
in
Australia
and
New
Zealand -
Editor.
THIS
instruction
is
being
given
to you in
advance
of
your
testimony
as an
expert
witness,
in
order
to
avoid
confusion
or
misunderstanding.
The
instruction
is
not
only
for
your
guidance,
but
also
for
the
guidance
of
counsel
and the
jury"
Because
you
have
qualified
as an
expert
witness,
your
testimony
is
governed
by
special
rules.
Under
ordinary
rules.
witnesses
are
allowed
to
testify
about
what
they
have
seen and
heard.
but
are
not
always
allowed
to
express
opinions
and
conclusions
based on these
observations.
Due
to
your
training
and
experience
YOU
are
allowed
to
draw
conclusions
and
give
opinions
in the
area
of
your
special
qualifications.
However,
you
may
not
state
conclusions
or
opinions
as an
expert
unless
you
also
tell
the
jury
what
investigations,
observation-
reasoning,
and
medical
theory
led to
your
opinion.
As an
expert
witnevs,
you
may,
if
you
wish
and
if
you
feel
you can,
give
your
opinion
about
whether
the
defendant
suffered
from
a
mental
disease
or
defect.
You
may
then
explain
how
defendant's
disease
or
defect
relates
to
his
allegeo
offence,
that
is,
how
the
development
adaptation,
and
functioning
of
defendant's
behavioural
processes
may
have
influenced
his
conduct.
This
explanation
should
be so
complete
that
the
jury
will
have
abasis
for
an
informed
judgment
on
wheth-
er
the
alleged
crime
was a.
"product"
of
his
mental
disease
or
defect.
But
it
\\'111
not
be
necessary
for
you to
express
an
opinion
on \\
hether
the
alleged
crime
was
a
"product"
of a me Hal
disease
or
defect
and you
will
not
be asked to do '-,0.
It
must
be
emphasised
that
you
are
to
give
your
expert
diagnosis
of
the
dpfend-
ant's
mental
condition,
This
word
of
caution
IS
especially
Important
if you
give
an
opinion
as to
whether
or
not
the
defendant
suffered
from
a ..
mental
diseave
or
defect"
because
the
clinical
diagnostic
meaning
of
this
term
may
be
different
from
its
legal
meaning.
You
should
not be
concerned
with
it~
legal
meaning.
Neither
should you
consider
whether
you
think
tlu s
defendant
should be
found
guil
ty
or
responsible
for
the
alleged
cri
me. These
are
questions
for
the cou
rt
and
jury.
Further,
there
are
cuns.ider
ations
which
may
he
relevant
in
otherproceed-
ings
or
in
other
contexts
\\
hich
are
not
relevant
here:
for
example.
how
the de-
Iendants
condition
mrght
change,
or
whether
he needs
treatment.
or is
treatable,
or
dangerous,
or
whether
there
are
adequate
hospital
facilities.
or
whether
com-
mitment
would
be best
for
him.
or
best
for
socrety
What
is
desired
in
this
case is
the
kind
of
opinion
you
would
give
to a
family
which
brought
one of
its
members
to
your
clinic
and asked
for
your
diagnosis
of
his
mental
condition
and a
descrip-
tion
of
how
his
condition
would
be
likely
to
influence
hj~
conduct.
Insofar
as
counsels
questions
permit,
you
shoulJ
tesuf
yin thlr.;
manner.
When you
are
asked questions
which
fall
within
the
scope
of
your
special
train-
ing and
experience,
you
may
answer
them
if you
Ieel
competent
to do (.;0;
other-
wise
you
should
not
answer
them.
If
the
answer
depend", upon
knowledge
and
experience
generally
possessed
by
ordinary
citizens,
for
example.
questions
of
morality
as
distinguished
from
medical
knowledge,
you should not
answer.
You
should
try
to
separate
expert
medical
judgments
from
what
you
may
call
"lay
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