An advocate is obliged to assist the court in reaching a conclusion that is favourable to his or her client. Thus, advocacy is not necessarily concerned with finding the truth of a matter, but of finding what is considered to be favourable to a specific party in a dispute. The party that can convince the court takes the day. This is realised through interpreting evidence (both oral and written) in support of specific assertions. However, the extent to which an advocate can adduce evidence in court in support of the client's case remains to be seen.

Unlike advocates, expert witnesses are responsible for leading the court to the correct conclusion.(1) The evidence of expert witnesses is heavily relied on, given their expertise in the specific field in question. However, this does not suggest that experts' evidence is to be taken as the absolute truth – what of an instance where the 'expert' happens to be a polygraph or lie detector test? Can a polygraph-generated report be adduced in court and, if so, to what extent?


The Evidence Act(2) does not provide directly for the use of lie detectors or the admissibility of polygraph reports in court. However, the act provides for the admissibility of computer-generated reports, with certain qualifications.(3) Information must be collected in respect of activities that are regularly carried out and be fed into a computer during the ordinary course of activities. Provided that lie detector tests are conducted regularly, they fall within the provisions of the law. The ordinary course of business would therefore constitute ordinary conduct of a lie detector test.

In civil cases, admissibility of evidence will come into play and the court must submit evidence according to the conduct of the parties during the administration of the lie detector test. The consent of the tested party is important. Written consent must demonstrate that the test was not taken under duress or undue influence and clarify the conditions under which the test was taken. The signature of an agreement ought to be witnessed by independent witnesses. It may also be advisable to notify the parties involved and request their consent for the results to be used as evidence in court.

In Darn Otieno v Stanbic Bank Kenya Limited(4) the court observed that the plaintiff had consented to undertake a lie detector test, despite his allegations of duress in signing it; the Evidence Act provides that a signed document speaks for itself and oral evidence cannot controvert it. Additionally, the court held that even if the plaintiff could prove duress when signing his consent, the defendants could not be liable as the Anti-banking Police Fraud Unit which administered the test was not shown to have received directions to conduct investigations from the defendants and therefore could not be said to have been their acting agents.


A critical look at the use of polygraph tests in other jurisdictions demonstrates that it is a contentious issue. Countries such as India have set out guidelines to facilitate polygraph test administration and Kenya would be well advised to follow suit. While the courts have not dispensed with lie detector admissibility, the legislature has issued no specific laws on the matter. While documents such as financial statements or architectural drawings are considered to be computer-generated output, the peculiar nature of polygraph tests due to their subject matter puts admissibility into disarray. Specific legislation is required in this regard.

For further information on this topic please contact Anne Njoroge or Paul Thuo at Njoroge Regeru & Company by telephone (+254 020 261 2531) or email ( The Njoroge Regeru & Company website can be accessed at


(1) P Murphy, Murphy on Evidence, London: Oxford University Press, 2013.

(2) Cap 80 Laws of Kenya.

(3) Section 106B(2) Evidence Act.

(4) (2012) eKLR.

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