THE POLYGRAPH AS A TOOL FOR INVESTIGATIONS

Its Basis and Legal Implications

Supt Amar Singh Sidhu

INTRODUCTION

Historical Basis

People lie. Though difficult to admit so, we all lie and have lied, at one time
or the other. We do so for different reasons. Some lie to avoid hurting
others, whilst others just the opposite. But most of the time deception is for
a self-serving purpose. Lying has existed and will exist in all societies and
at all levels of life. It begins at the earliest possible stage of childhood and
continues till the time we leave this body. It is found in the lower reaches of
life to the highest spheres in business, politics and even religion.

As such the search for truth has been a universal and constant
endeavour that has dated back to ancient times. Primitive societies had
developed complex procedures founded on magic and mysticism in their
attempt to discover deception. Some of these rituals had a foundation
based on sound physiological principles, whilst others were more spiritually
inclined.

For example, in India, suspects who did not admit were required to
hold a burning object in their hands. They were considered to be innocent if
they remained unburned. Similarly, in Tibet, the accused and the accuser
were required to retrieve a stone from a boiling cauldron of water. The
truthful party is the one who is not scalded. In the Orient1, in determining
whether a person is telling the truth or not, one is required to chew dry rice
and then spit it out. The deceptive person is one who is unable to spit out
the dry rice. On the other hand the Arabs applied a hot iron to the tongue of
the accused. If he were telling the truth he would not be injured.

Researches in this field have used physiological principles to

explain some of the above. One of such is that fear is known to slow down
the digestive process, including salivation. Thus a deceptive person would
not be able to salivate normally, making it difficult for him to spit out the dry
rice. On the other hand an innocent party would have no difficulty in the
above. With regards to the burning object and the hot iron on the tongue,
1
Legend has it, that in Malaysia , during the times of the Malay warrior Hang Tuah, truth was
verified between individuals by the eating of beetlenut leaves that had earlier been
'spiritualized upon' by a 'bomoh' ( traditional Malay medicine men) . The one telling the truth
would be able to chew the leaves at ease whereas the one telling lies would vomit blood. See
Kassim Ahmad., Hikayat Hang Tuah, 1966, Dewan Bahasa Dan Pustaka.
The Ibans of Sarawak would settle a dispute on the truthfulness of a person by having a cock-
fight. The winner is the one telling the truth. This practice is still seen in the remote villages of
Sarawak.
The Chinese community of Malaysia verify the telling of truth by the beheading of a white
cockerel. See Cheah Chooi Chuan ( 1972 ) 1 MLJ 246
though there is no reasonable explanation, researches in this field have
based it on a mind-body interaction. 2

The Spanish Inquisition is a slightly more recent form of a truth

finding procedure. Though the trial by torture was almost guaranteed of a
confession, unfortunately it need not necessarily be the truth, as torture
persisted as long as the accused denied. A confession was obtained on the
pain of unspeakable atrocities, and all this in the name of truth.

In more modern times and often practiced generally by the police

forces of the world, though not officially, is the so called "third degree"
torture. Admissions are elicited through sleep and food deprivation. Bright
lights and general brutality is also a part of this technique of truth extraction.
Though admittedly it may be efficient but it cannot be admitted by the courts
of law.

This now leads us to a discussion of a more acceptable and

scientific mode of lie detector.

The Other Lie Detectors

There are several techniques that are well established and based on
scientific approaches, but not necessarily accepted by the courts of law.
They are:

1. Hypnosis

The concept here is that once a person is in a sleep-like state under

the control of the hypnotist, he is incapable of lying. But studies
reveal that in some cases the subjects had retained some control
over their utterances.3 Experts in the field of hypnosis have
generally agreed that the subjects can lie as effectively under the
hypnotic state as when he is fully conscious. Stan Abrams4, an
authority in polygraph testing states that because of the ability of
the individual to lie under hypnosis and the inability to determine
whether a subject is feigning this state, hypnosis has not been
proven to be a valid means of detecting deception.

2. Truth serums

It is assumed here that an individual in a heavily drugged state

does not have the capacity of deceiving. His appearance, slurred
speech, and difficulty of responding suggests that the drugged
subject lacks the defenses of feigning a response. Studies

2
Abrams, Stan, History of Polygraphy , In School of Polygraphy Reference Materials, Western
Oregon University.
3
Beigel, H.G. , Prevarication under Hypnosis , J . Cln. And Exp. Hypn. 1 ( 1953 )pg 32 -40
4 nd
Abrams, Stan ,The Complete Polygraph Handbook ( 2 ed )
 nevertheless reveal that only 50 percent accuracy is achieved in
actual circumstances.5 There is further criticism that, as in
hypnosis, the subject might continue to be deceptive under narcosis
and that the individual might become hyper-suggestible and
confess to a crime he did not commit.

Thus, with hypnosis and truth serums, the examiner can

never be certain of the meaning of his results. The subject who
appears non deceptive may only have accomplished a persuasive
enactment of the truth, while the individual who admits his guilt
could conceivably only be demonstrating his proneness to
experience guilt.6

Notwithstanding the above, truth serums can be used in

'third degree' interrogation techniques since in a drugged state the
subject is less capable of defending against a barrage of questions
and thus more apt to slip. This revealed information can be
employed for further investigations.

3. Word-association Test

Here the detection process is the word-association test combined

with a measure of the reaction time. Studies show that reaction time
is longer to key words than that to neutral stimuli.7 Writers in this
field have stated its limited use in that it is more of a test of guilty
knowledge rather than lie detection per se. Thus it can only be
used in cases in which the subjects have no awareness of some of
the pertinent details of the crime.

There are several other less well known modes of lie-detectors.

Some examples are the 'expressive movements test which reads and
translates the reflex movements and expressions of a person to determine
if he is telling the truth or otherwise. Another mode is the 'voice analysis'.
This voice stress evaluator measures the physiological changes in the voice
associated with stress. These above tests are still in the developmental
stage and its basis and accuracy is still being questioned.

Early Polygraphs.

The polygraph can be described as an instrument that measures

physiological reactions. It operates by measuring the reactions of the
involuntary nervous system i.e. those functions of our body that we can't
control.

5
Inbau, F.E. , Methods of Detecting Deception , J. Crim L 24 ( 1934 )
6
Abrams, Stan, The History of Polygraphy, School of Polygraphy Reference Materials,
Western Oregon University.
7
Jung, C.G., The Association Method, American J. of Psychology,221 ( 1910).
 In early 1895 Cesare Lambroso scientifically measured the pulse
rate during questioning of a suspect. He reported that he was able to
determine a lie by measuring the changes of pulse rate. This principle was
extended when in 1914, Vittorio Benussi demonstrated that by comparing
the inspirations and expirations he found that the duration of inspiration
increased following lying. Another American researcher, Marston, then
found out that the systolic blood pressure was affected by fear and anger,
which he associated with lying and the concern of being detected.

The above were only a primitive precursor to the present polygraph

since it measured only one area of physiological functioning. As such in
1921 one John Larson combined some of the features of the above, and
incorporated an 'ink polygraph' which were used by cardiologists. He also
employed a word association technique and inserted a crime word at every
third word. This was later improved upon by Leonarde Keeler who made it
compact enough to be portable. Later psychologists added on a
galvanometer and improved on the control question to its now present
state.

THE POLYGRAPH INSTRUMENT

At present there are two general types of polygraph instruments. They are
the analog version which measures the physiological changes via
mechanical means. The other is the newer digital type8. This digital
polygraph measures the physiological changes which are then relayed to a
computer which is incorporated with the necessary software.

The polygraph consists of the following components:-

i) The Pneumograph

The pneumograph consists of a rubber strapping attached to the

chest of the subject. It measures the subject's breathing activity
during the interview.

ii) The Cardiograph

This is similar to the blood pressure cuff instrument used by

physicians. It measures the blood pressure changes and the pulse
rate of the subject.

iii) The Galvanometer (The Electrodermal Response - EDR)

It measures the skin's resistance to electricity by the use of two

electrodes which are attached to the finger tips of the index and ring

8
There are two main companies that manufacture these digital versions. They are by the
th
C.H.Stoelting Company and the other is Lafayette Instrument Co, Sagamore Parkway & 9
Road, Lafayette, Indiana. USA.
 fingers. It thus detects the changes in the examinee's skin
resistance, which is then amplified and recorded.

The data from the above three instruments is simultaneously

recorded on to a mechanical needle chart ( if analog version ) or computer
screen ( if the digital version ) . The chart has then to be translated by the
polygraphist by employing comparative scoring results.

POLYGRAPH TEST PROCEDURE

The polygraph cannot be just plugged on to an individual and the 'polygraph

examiner' 9 made to see if the person is lying or not to a question. There are
two main components to a polygraph examination. They are the polygraph
instruments itself which has been described above, and not less in
importance is the polygraph examiner10 and the interview process. Thus the
polygraph procedure can be divided into four distinct phases:

1. Data Gathering

Complete details must be gathered on both sides of the question

and the person to be tested. Details of the examinees medical
state are important. Those with severe heart conditions, epileptics
and even those having a bad cold and wheezing, coughing or
sniffing could invalidate the test. They should be excluded from
examination.

The examiner should also examine the complete records11

relating to the act in question before the test date. Thus in criminal
cases the police records should include the statements of the
victim, the accused, the witnesses and any information which is
relevant.

2. Pretest Interview

This is the most important part of the entire test process. Here
rapport must be established with the examinee and the
polygraphist, thus allying his anger, suspicion and anxiety. The

9
To be a polygrapher in the U.S. certain requirements have to be fulfilled. The applicant must
either successfully complete the required training in detection of deception at a polygraph
school approved by the Department, or submit evidence of satisfactory completion of
substantially equivalent training if the polygraph school at which the applicant received training
in the detection of deception is not approved by the Department.
http://www.vapolygraph.com/PolygraphExaminers.htm.
10
Courses in polygraphy are conducted by the Western Oregon University School Of
Polygraphy which is for a period of 3 months. Other examples of such courses are by the
Canadian Police College ( 11 weeks ) and the Argenbright International Institute of Polygraph,
Atlanta, Georgia.USA. Private practitioners also offer numerous services of polygraph training,
eg see http://www.polygraphy.co.za/html/body_why_us__.html. For a postgraduate M.Sc (
Polygraphy ) the University of Chemical Technology and Metallurgy ( UCTM ) ,Sofia, Bulgaria
offers a course.
11
This can be argued as liable to being biased on the part of the examiner.
polygraphist must present himself as being highly objective,
professional and interested only in learning the truth. The subject
must be made aware that if he lies, the examiner will know it. Thus
the stimulation of fear of detection is the major purpose of the
pretest interview.

Also during this stage, further background data is obtained

from the examinee. We may inquire whether he has been subjected
to a polygraph test before and how much information he has about
polygraphy. Thus the more aware and informed he is regarding
polygraphy the more apt he is towards counter measures.

When all the necessary background data is obtained, the

examinee is then questioned about his knowledge on the issue
under investigation. The subject is allowed to present his case
without interruptions. After the description is complete, he may be
asked further questions for clarification. It is through this that the
polygraphist can determine which questions should be asked.

Then comes the stage of question formulation. This will

depend on the type of procedure utilized and the case facts. There
are several types of questions to be posed to the examinee. They
are the:-

i) Relevant Question

This relates to the issue at hand. It should be short, understandable

to the examinee, and to the point. They must also be completely
unambiguous so that they cannot be confused.

ii) Control Questions

The control question is an assumed or probable lie. It is important

since the issue of truthfulness or deception is based on a
comparison of the reaction towards the relevant question to the
control question.

iii) Irrelevant Questions

Irrelevant questions are neutral questions that are factual in nature

and easily answered without thought and stress. Irrelevant
questions provide a picture of the individuals normal response
pattern under the stress of taking the examination.

iv) Sacrifice Relevant Questions

This is usually placed in the second position of the test and serves
to diminish the emotional reactivity. It is not scored because its
purpose is to draw the fear from the first relevant question.
 v) Symptomatic or Outside the Issue Questions

The above question attempts to determine if there is some outside

issue that is more disturbing to the subject than the issue in the
test.

After that the test questions will be formulated and the

polygraph procedure will be explained in detail. Only then will the
examination be carried out.

3. Actual Testing

At this stage the subject is actually tested. The instruments are

attached on him and the questions begin. The polygraphist will note
exactly when the question had started and ended, and what and
where the response occurred.

The numbers of questions are not limited but they are

generally about 10 to 15 in all. After each question there is a fifteen
to twenty second pause. When all the questions have been
administered the examiner may repeat the test up to three times.
The first two may follow the numerical order of questions set,
whereas the third can mix them.

4. Scoring and Chart Interpretation

When the testing is completed, the tracings are interpreted and

scored. A numerical scoring is given to the responses during
questioning. This system provides an objective and measurable
evaluation of the differences in response between the control and
the relevant questions.

There is a consensus of opinion amongst polygraphists that

the changes in the tracings are indicative of deception. But there is
disagreement as to which sensor is the most valuable in detecting
deception in order of priority. Generally the polygraphists report that
the EDR response is the most valuable measure.

Nevertheless for a polygraph score on a question, the

readings of all the sensors are compared to that of the control
question. This is a complex procedure. Thus the total score
determines the finding of deception indicated (DI), no deception
indicated (NDI) or inconclusive.

The polygraph test is now complete and the polygraphist can make
his finding if the examinee is telling the truth or is being deceptive. His
opinion will be based on the result scores as obtained above and there is
no guess work involved. If he cannot make his findings from the score
results due to the lack of marked sensor changes than his final outcome
would be just 'inconclusive'.
LEGAL ASPECTS OF POLYGRAPHY EXAMINATION

To date, the question of relevancy and admissibility of the opinion evidence

of the polygraph expert has not been discussed in the Malaysian courts.
Nevertheless there is growing awareness of this field of 'lie-detector' as can
be seen in the Singapore case of Eldon12 where the plaintiff lawyer argued
that his client's testimony was unshakeable and that the plaintiff was willing
to even undergo a polygraph test to prove his truthfulness. It is expected
that more such applications on the relevance and admissibility of such
evidence would be made in Malaysian courts.

For the sake of discussion, there can be three instances when

polygraph tests can be conducted and then sought to be introduced in
court. They are:

1. Polygraph test conducted before trial, and its evidence

sought to be adduced in court.

2. Polygraph test to be conducted during trial.

3. Polygraph test conducted for the sake of investigations only

1. Polygraph test conducted before trial

and its evidence sought to be adduced in court.

In such cases the polygraph test is taken earlier and an application is made
to have its evidence adduced in court. Before this can be done we have to
find out first whether the opinion evidence of a polygraph expert is relevant.
Then we have to see whether its evidence is admissible in court.

a) The issue of Relevancy of Polygraph Evidence

Before the opinion evidence of any expert could be considered by

the courts, including that of polygraph experts, it has to first be
shown to be relevant as required under section 45 of the Evidence
Act 1950 which states:

(1) When the court has to form an opinion upon a point of

foreign law or of science or art or as to identity or
genuineness of handwriting or fingerprint impressions, the
opinions upon that point of persons specially skilled in
that foreign law, science, or art, or in questions as to
identity or genuineness of handwriting or fingerprint
impressions, are relevant facts.

12
Eldon v PP (2001) 1 SLR 710
 (2) Such persons are called experts.

Thus opinion evidence of an expert is relevant if it is on matters of

foreign law or of science or art, or as to the identity or genuineness
of handwriting or finger impressions.

Can 'polygraphy' be considered, in law, to be on a point of

science?

As was discussed earlier 'polygraphy' is the study on the change of

the physiological reactions towards questions. The physiological
reactions measured are the blood pressure changes, the breathing
activity and the skin's resistance to electricity. This change in the
measure of the reactions of the involuntary nervous system is used
to determine if a person is lying towards the question or not. This
study of 'polygraphy', would in the literal sense, fulfill the
requirements of the terminology ' science'.

In addition, with reference to the legal framework, this

expression 'science' is capable of a wide interpretation13 . Raja
Azlan Shah J (as His Highness then was) had this to say regarding
the expression 'science or art', in the case of Chandrasekaran 14, a
High Court decision:

"The expression 'science or art' is elastic enough

to be given a liberal interpretation. ...was not
specifically mentioned in section 45, then equally
there is no mention of handwriting or foot-print or
telephony and yet the evidence of handwriting,
foot-print or telephonic experts has been held
admissible. So also of ballistic or medical experts
who too have not been mentioned in section 45."

Thus, though there is no mention of the word polygraph

expert under section 45 of the Evidence Act 1950, it would
nevertheless include it if we construe the liberal interpretation given
by Raja Azlan Shah J ( as His Highness then was ).

This has been given further weight in the case of Leong

Wing Kong 15 where it was stated by Yong Pung How CJ that,

"...if the evidence covers an area of 'science or

art'. The scope of the term has been widely
construed and is not restricted to the subjects of
pure science and art."

13 nd
Paul , Augustine , Evidence; Practice and Procedure ( 2 ed 2000) Malayan Law Journal
14
Chandrasekaran v PP (1971) 1 MLJ 159
15
Leong Wing Kong v PP (1994) 2 SLR 54
 With all the above it can be seen that the polygraph opinion
is within the expression 'science' as required under section 45 of the
Evidence Act 1950.

The question of 'persons specially skilled in that.

Now comes the question of the expertise of the polygraph expert.

Does it fulfill the requirements of the Evidence Act 1950? The test
to be applied to determine whether a person is a polygraph expert
or otherwise is the same as for other experts. A useful pointer is as
stated by Mohamed Azmi SCJ in the case of Junaidi 16 :

The speciality of the skill required of an expert

under section 45 would depend on the scientific
nature and the complexity of the evidence sought
to be proved. The more scientific and complex the
subject matter, the more extensive and deeper will
the court be required to enquire into the
ascertainment of his qualification or experience in
the particular field of art, trade or profession."

His Justice further added that:

"The lack of qualification or experience on the part

of the expert must necessarily affect the weight of
the evidence rather than admissibility. But where
the evidence is of a complex and scientific nature,
the absence of both qualification or experience
can certainly affect admissibility."

Thus for the evidence of a polygraph expert to be adduced

in court it must be first proved that the polygraphist is in fact an
expert as required in law. Being a study of physiological changes,
which is of a scientific nature, the polygraphist must show both
qualification17 and experience.

Thus 'prima facie' the evidence of a polygraph expert would

fulfill the requirements of relevancy as required under section 45 of
the Evidence Act 1950. It is a science, and provided the polygraph
expert can show his qualifications and experience the evidence of
such is relevant. But now the main question is admissibility of such
evidence. Is the evidence of the polygraph expert admissible?

b) Admissibility of polygraph expert opinion.

It is a generally established principle of case law that expert

evidence is only admissible to furnish the court with scientific
16
Junaidi b. Abdullah v PP ( 1993) 3 MLJ 217
17
see footnote 10 for courses available.
 information which is likely to be outside the experience and
knowledge of a judge.
18
This opinion can be seen in the case of Chou Kooi Pang
where Yong Pung How CJ stated that:

".. it is well established that expert opinion is only

admissible to furnish the court with scientific
information which is likely to be outside the
experience and knowledge of a judge. If, on the
proven facts a judge can form his own conclusions
without help, the opinion of an expert is
unnecessary."

In addition to the above Lawton LJ in the case of Turner 19

had earlier stated the inadmissibility of opinion evidence which was
in fact within the knowledge and experience of the court, but
dressed up with scientific qualification and knowledge. He stated
that:

"In such a case if it is given dressed up in scientific

jargon it may make judgement more difficult. The
fact that an expert witness has impressive
scientific qualifications does not by that fact alone
make his opinion on matters of human nature and
behaviour within the limits of normality any more
helpful than that of the jurors themselves; but there
is a danger that they may think it does ."

Thus we can see that the scope of the section 45 is for

opinion evidence which is outside the knowledge and experience of
the court. This assertion is fortified by the following, where Abdul
Hamid FJ (as he then was) stated in the case of Syed Abu Bakar 20

"The scope of this section...while recognizing that

opinion in so far as it may be founded on legal
evidence shall be the function of the tribunal
whose province alone it is to draw conclusions of
law or fact."

There are several instances where courts have rejected the

admissibility of so called expert evidence on the ground that it
encroaches into the judges domain i.e. within the knowledge and
experience of the judge. In Turner's case the court rejected the
opinion evidence of the expert on the question of acts of blind rage
when discovering unexpected wantonness on the part of their loved
ones. This the court held was matters which are well within ordinary

18
Chou Kooi Pang v PP ( 1998 ) 3 SLR 593
19
R v Turner ( 1975 ) 1 All ER 70
20
Syed Abu Bakar b. Ahmad v PP (1984) 2 MLJ 19.
 human experiences. In the case of Weightman21 a psychiatrist's
evidence was held inadmissible where its purpose was, in effect, to
tell the jury how an ordinary person, not suffering from any mental
illness, was likely to react to the strains and stresses of life.

The question now is: Is the polygraph expert's evidence within

the knowledge and experience of the court?

There are no local cases which discuss on the issue of a polygraph

experts testimony. On the other hand, the results of polygraph tests
and narcoanalysis (truth serums) seem to be invariably rejected in
the criminal Courts of the United States, where the issue has been
considered quite often. In contrast, in the British Commonwealth
there has been little or no consideration of it. Nevertheless there is
an unreported judgement of the Privy Council decision of an appeal
from the Court of Appeal of Jamaica. This is the case of Bernal &
anor 22.

Facts of Case :

In this case the appellant and one Christopher Moore were arrested
and charged for the possession and exporting of ganja. In the case
for Bernal, on the issue of credibility, his counsel sought to
introduce the evidence of a polygraph test conducted by a
polygraph expert. But this evidence was rejected by the Resident
Magistrate as being inadmissible. They were convicted and
sentenced by the Magistrates Court in Kingston, Jamaica.

Their appeals against conviction and sentence were later

dismissed by the Court of Appeal of Jamaica. The Court of Appeal
of Jamaica decided that the Resident Magistrate had been correct
in deciding that the polygraph evidence which counsel wished to
call on behalf of the appellant, Bernal, was not admissible for the
purpose of supporting Bernal's credibility.

They thus appealed to the Privy Council on specified

questions as involving points of law on exceptional public
importance. The questions (with reference to polygraph testimony
only) were:

a) Whether the learned Resident Magistrate erred in law in

holding that to permit an expert to give opinion evidence of
polygraph tests which he administered on the appellant
would encroach on the learned Magistrate's judicial
function.

21
R v Weightman (1991 ) 92 Cr App R 291
22
Bernal & Anor v R ( unreported) P/Council decision dated 28.April.1997.
see http://lexis.com/ ( England and Wales Reported and Unreported Cases )
 b) Whether evidence of the findings of a polygraph
examination by a competent expert are admissible where
such evidence is sought to be adduced by a defendant in
support of his defence, in particular to rebut an allegation of
guilty knowledge.

Held by Privy Council:

The court held that:

i) The Resident magistrate was right in holding that the

polygraph test was not infallible and that he was fully
entitled to conclude that in the circumstances to admit the
evidence would encroach on his judicial function.

ii) Agreeing with the Supreme Court of Canada case in

Beland 23 they summarized the reasons as follows:

The admission of such evidence offends several of the

rules of evidence.

a) Firstly, to admit evidence of the polygraph

examination to bolster the credibility of the accused
as a witness offends the well-established rule
against adducing evidence solely for the purpose of
bolstering a witness's credibility24

b) The admission of polygraph evidence would offend

the rule against admission of past consistent out-of-
court statements25.

c) Polygraph evidence which the accused proposed to

tender would be entirely self serving and shed no
light on the real issues that were before the court.

d) The evidence which the polygraph examiner would

give, would also offend the rule relating to
character evidence26 since the operator would be

23 th
R v Beland and Phillips ( 1987 ) 43 DLR (4 ) 641
24
Compare the Malaysian position where sec 146 (a ) Evidence Act 1950 states that a
witness may be cross examined to test his accuracy, veracity or credibility. For commentaries
on the distinction between credit and credibility , see : Paul. Augustine., Evidence :Practice and
nd
Procedure. 2 Ed. Malayan Law Journal,.pp 1003.
25
Compare also the Malaysian position where section 157 of the Evidence Act 1950 states
that :- "In order to corroborate the testimony of a witness , any former statement made by him
whether written or verbal, on oath, or in ordinary conversation , relating to the same fact at or
about the time when the fact took place, or before any authority legally competent to
investigate the fact, may be proved.". For the principle and scope of section 157 see Paul.
nd
Augustine., Evidence: Practice and Procedure. 2 Ed. Malayan Law Journal, pp1036- 1043.
26
For a Malaysian perspective see section 53 of the Evidence Act 1950 which states :- " In
criminal proceedings the fact that the person accused is of a good character is relevant.". For
 called as a witness for the purpose of bolstering the
credibility of the accused and in effect to show him
to be of good character by inviting the inference
that he did not lie during the test. It was not
evidence of general reputation but of a specific
incident.

e) Finally the evidence would not be receivable as

expert evidence. The function of an expert is to
provide the jury or the trier of fact with an expert's
opinion as to the significance of, proved facts in a
field in which the expert witness possesses special
knowledge and experience going beyond that of
the trier of fact. Where, however, the question is
one which falls within the knowledge and
experience of the trier of fact there is no need for
expert evidence and his opinion will not be
received.27

In this case the sole issue upon which the polygraph

evidence was tendered was the credibility of the accused, an issue
well within the experience of judge and juries and one on which no
expert evidence is required.

Similarly in the case of Mckay 28 the New Zealand Court of

Appeal held that polygraph evidence was inadmissible since:

"The time could come and when we should make

further exceptions in the light of what wider
scientific knowledge and improved techniques
show to be desirable. But the use of drugs and
instruments such as the polygraph to delve into
man's unconscious mind can conflict with the
upholding of human dignity. The problem is a
complex one. Not all means of arriving at truth can
be justified, and the use of drugs and machines, if
uncontrolled, could lead to practices as
objectionable as those adopted in more barbarous
ages."

Thus as shown above, the evidence of a polygraph expert who had

conducted the test earlier and now wishes to have it admitted in court
though relevant via section 45 of the Evidence Act 1950, is not admissible.
The reasons for its inadmissibility are many, as stated above, but the one

nd
its principle and scope see Paul. Augustine., Evidence : Practice and Procedure. 2 Ed.
Malayan Law Journal pp 474.
27
Syed Abu Bakar b Ahmad v PP (1984 ) 2 MLJ 19 (Federal Court ) , Chou Kooi Pang &
anor v PP (1998 ) 3 SLR 593 ( Court of Appeal ), Ong Chan Tow v R (1963 ) MLJ 160 (
High Court ).
28
The Queen v Mckay ( 1967 ) NZLR 139 ( Ct. of Appeal )
thats most relied upon is that the purpose of expert evidence is thus to
assist the trier of fact by providing special knowledge that the ordinary
person would not know. Its purpose is not to substitute the expert for the
trier of fact.

2. Polygraph Test conducted during trial

There have been cases where, during a trial in progress there have been
applications for a polygraph test to be conducted. A recent example is the
Singapore case of Eldon29 where as stated above, the appellant
volunteered to undergo a polygraph test to prove his truthfulness. But in this
case no formal application was made to have a polygraph test conducted.
As such there was no decision on the matter. Nevertheless there is the
Canadian case of Beland 30 which is precisely on the above matter. In the
testimony, the respondents asserted that the evidence of the Crown's
witness was false and denied any participation in the alleged conspiracy.
The respondents made an application to permit them to take a polygraph
examination and submit the results in evidence.

It was held by the Supreme Court of Canada, Per Dickson CJ , and

Beetz , McIntyre and Le Dain JJ:

"The results of a polygraph examination are not admissible

as evidence. The admission of such evidence would
offend well established rules of evidence, in particular, the
rule against oath-helping, which prohibits a party from
presenting evidence solely for the purpose of bolstering a
witnesss credibility."

They further held that:

"The evidence of polygraph evidence will serve no purpose

which is not already served. Such admission will disrupt
proceedings, will open the trial process to the time
consuming and confusing consideration of collateral issues
and will deflect the focus of the proceedings from the
fundamental issue of guilt or innocence.The results
recorded by the polygraph instrument, their nature and
significance will reach the trier of fact through the mouth of
the operator. Human fallibility will thus still be present, but
now fortified with the mystique of science."

Thus we can see that courts are reluctant to admit the evidence of
opinion of a polygraph expert during the course of a trial for the purpose of
bolstering one's credibility.

29
Eldon v PP ( 2001 ) 1 SLR 710
30
R v Beland ( 1987 ) 2 SCR 398
3. Polygraph test conducted for the sake of investigations only

Since polygraph examinations cannot be admitted in court they than can

only be used for investigation purposes. The investigation officer may use
the polygraph test to help him in determining the truthfulness of a witness. It
can be used to cross-examine a witness during investigations so as to
come with the true picture of the evidence. A point in favour for the
investigator is the case of Siew Ah Beng31 where the Singapore High Court
had to deliberate whether the confession which was recorded, as a result of
a polygraph test that was shown to the accused, was admissible. The
polygraph test had indicated that the accused had lied.

The appellant had claimed that the recording officer had fabricated
her confession and had induced her into signing it by showing her the
polygraph test results, accusing her of lying. The court held that the act of
conveying the results of the polygraph test would not render her confession
inadmissible, provided that nothing more was done which could be
construed as an inducement, threat or promise.32 The judge also stated
that:

"It was held in Mahendran33 that there was no reason why

an accused person who was charged for unauthorized
drug consumption could not be shown the urine test
results before the statement was recorded, provided that
nothing more was done which could be construed as an
inducement, threat or promise. Similarly, the act of
conveying to the appellant the results of her polygraph test
per se would also not render her statement inadmissible."

CONCLUSION

In conclusion, we can see that a polygraph examination is a measure of the

physiological changes recorded that are used to determine the issue
whether a person is telling the truth or otherwise. Though it can be
considered a science, it still entails a great dependence on other sources
i.e. the examiner and his interpretation of the results. This is unlike the
science of fingerprint and DNA evidence where it is less dependent on the
examiner. Both these tests are fully science based and are not related to
the mode or way of interpretation. In other words there are no two ways of
interpreting a fingerprint or DNA result. This is unlike that of a polygraph
where the outcome is based on a probability and comparison with the
control question.

31
Siew Ah Beng v PP ( 2000 ) 3 SLR 773
32
For cases and a discussion on what constitutes inducement, threat, promise and also the
admissibility of statements made to the police see : Mimi Kamariah Majid. Criminal Procedure
rd
in Malaysia 3 Ed University of Malaya Press.
33
Vadugaiah Mahendran v PP ( 1996 ) 1 SLR 289
 Further the probabilities involved in the science of fingerprint and
DNA evidence is very precise. For example in DNA matching, the
Chemistry Department of Malaysia uses 9 loci in its comparative analysis.
Studies34 show that the probability of all 9 of them matching in individuals is
1 : 2.152 x 109 . Similarly, for fingerprint comparative analysis it is based on
the comparison of 12 characteristics. Numerous studies into the
probabilities of individual fingerprints matching in all 12 characteristics have
been shown to be 1 : 13.84 billion.35

On the other hand the polygraph is not an infallible36 method of

determining the truthfulness of a subject. There are so many variables. The
test results could depend on the subject - whether he has been tested
before, whether he is co-operative or otherwise etc.37 It would also depend
on the examiner - how detailed is the data gathering and pretest interview.
Then comes the scoring as it can be construed, but we can see that it is not
so comprehensive a mode as that of fingerprint and DNA examination.

Not withstanding the above, polygraph examinations though not

admissible in court can be used in investigative procedures. It can assist the
examiner to delve into the truthfulness of the witness and also be used to
confront the witness as was done in the case of Siew Ah Beng38, thus
leading to a better level of investigation.

34
Jabatan Kimia , Malaysia.
35
Simon Newcomb Theory, Encyclopedia Britannica.
36
Bernal & anor v R ( unreported ) P/Council decision dated 28.April 1997 .See
http://lexis.com/ (England and Wales Reported and Unreported Cases )
37
See book on beating the polygraph. Williams. Dough., How To Sting The Polygraph , Also
see internet articles at http://www.polygraph.co.za/polygraphpolysting.htm, and
http://www.polygraph.com/
38
Siew Ah Beng v PP ( 2000 ) 3 SLR 773