OVER time there has, to some degree, been conflicting laws regarding the extent of the admissibility of polygraph test results in disciplinary hearings. More especially, it has related to whether an employer can rely solely on a failed polygraph test to prove the guilt of an employee on the balance of probabilities.

Employers are all too frequently of the mistaken impression that a failed polygraph test is enough to prove guilt. Not so, say our courts. The recent Labour Court matter of Mustek v Tsabadi and others (JR 2732/2010: judgment day March 2, 2013) reiterated and reconfirmed the extent to which polygraph test results may be used to prove guilt in disciplinary hearings. In that case, eight laptop computers went missing from the employer’s premises. The employer administered polygraph tests on all employees who had access to the area from which the laptop computers had gone missing. Four of the 67 employees tested failed the polygraph test and were subsequently dismissed based on those results only.

Judgment in this case emphasised certain important factors to be considered regarding the admissibility and extent to which polygraph test results may be used in disciplinary hearings. The court held that: “Our courts have approached the use of polygraph tests with much circumspection, and it is now accepted that the result of a properly conducted polygraph is evidence in corroboration of the employer’s evidence and may be taken into account as a factor in assessing the credibility of a witness and in assessing the probabilities.”

It became apparent in a separate arbitration hearing at the Commission for Conciliation, Mediation and Arbitration, that another commissioner had, in fact, condoned the admissibility of the polygraph tests alone and admitted this was sufficient evidence to prove guilt on the balance of probabilities.

However, in the Labour Court judgment, the judge noted that commissioners are not bound to follow awards of fellow commissioners, even if two separate arbitration hearings are faced with the same facts. More especially, it was held that: “It is factious to suggest that one commissioner should complacently endorse the finding of another commissioner where the two matters have their origins in the same incident. The rationale for the first commissioner’s decision has to be analysed. There can be any number of reasons why that commissioner arrived at the conclusion he did. To argue that a commissioner is bound by the findings of another commissioner is repugnant to the rules of precedent.” The judgment continued that, in essence, polygraph test results are indeed admissible in disciplinary hearings only insofar as they corroborate or support more direct evidence.

It is quite clear that our law has established a now well-established precedent that if the only evidence levelled against an employee is a failed polygraph test, it will never be sufficient proof in its own right to prove that the employee is guilty on the balance of probability. That is not to say, of course, that polygraph test results are inadmissible. On the contrary, they are. However, insofar as polygraph tests ought to be admitted in a disciplinary hearing, and indeed an arbitration hearing, such failed polygraph test results are only of value to the extent that they support more direct evidence introduced during the disciplinary or arbitration hearing. After all is said and done, polygraph test results have value as corroborating evidence only and will never be sufficient as free-standing evidence to prove a case on a balance of probabilities.

Tony Healy is a labour law expert at labour law consultancy Tony Healy & Associates.

Visit www.tonyhealy.co.za. Call 086 111 5375 or email info@tonyhealy.co.za

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