The Production of Evidence in Blood Test Cases
| Published date | 01 October 1931 |
| Date | 01 October 1931 |
| DOI | http://doi.org/10.1177/0032258X3100400408 |
| Subject Matter | Article |
The Production
of
Evidence
in
Blood
Test
Cases
A
FEW
NOTES
HE
precipitation reaction test for determining the origin
T
of bloodstains may be
said
to be, in its modern develop-
ments, absolutely conclusive.
A
few years ago, comparatively speaking,
a
cautious ex-
pert, in describing the reliability and evidential value of the
test, would claim for
it
no more than that
it
was to a very
high degree of probability conclusive, although, even
so
far
back as twenty-five years ago, Continental and American
writers were prepared to maintain its absolute certitude.
To-day,
in
instructing
a
jury, few judges,
if
any, would
hesitate to describe the test as practically infallible-the enor-
mous mass
of
information and experience accumulated in
recent years having fully established its reliability.
However true this may be of this or any other class
of
expert evidence,
if
the police and prosecution fail to present
the complete chain of collateral evidence necessary to ensure
that the expert conclusions carry the full weight they are
entitled to, the evidence may be seriously weakened or rendered
entirely nugatory.
Expert evidence, from its nature, is invariably circum-
stantial, and
it
is
a
sine
qua
non
that the chain
of
circumstantial
evidence must be
as
far
as
is humanly possible complete
if
a
court is asked to convict on
it
alone.
In
cases
involving blood
tests
it
is
an elementary propo-
sition that the investigating officer must ensure that the article
from which the stains for testing are derived is satisfactorily
connected up with the other appropriate parts of
his
case and
553
To continue reading
Request your trial