When is a polygraph mandatory?

Many employers still believe that they have the right to simply subject an employee to a polygraph test, and that the result provides conclusive evidence that the employee is guilty and may therefore be dismissed.

Those employers would be wrong on all counts.

The question as to whether an employer can rely on a polygraph test in any circumstances to prove an employee’s guilt, was settled by the Labour Appeal Court (LAC) on 13 May 2014 when it handed down the judgment in the matter of DHL Supply Chain (Pty) Ltd v De Beer NO and others .

The LAC quoted, with approval, from the judgment in the matter of Truworths Limited v Commission for Conciliation, Mediation and Arbitration and Others (JR789/07).  The Labour Court held that:

“[37] A polygraph test on its own cannot be used to determine the guilt of an employee (see also John Grogan Workplace Law 9th edition page 160.) However, a polygraph certainly may be taken into account where other supporting evidence is available provided also that there is clear evidence on the qualifications of the polygraphist and provided that it is clear from the evidence that the test was done according to acceptable and recognizable standards. At the very least, 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. The mere fact that an employee, however, refuses to undergo a polygraph is not in itself sufficient to substantiate an employee’s guilt”

The reason why an employer may not draw a negative inference from an employee’s refusal to undergo a polygraph is because the onus is on the employer to prove that the employee is guilty – it does not require the employee to prove his innocence by being prepared to take polygraph test.

Further to that Section 10 of the Constitution provides that everyone has the right to inherent dignity while section 12 protects the individual’s control over his own body and the right not to be subjected to medical or scientific processes without his consent.

Even if an employer is of the view that the result (“deception indicated”) is sufficient to support a suspicion of wrongdoing, he may not dismiss the employee on those grounds, given that neither a polygraph result on its own nor his suspicion proves that the employee was lying or is guilty as the result does not provide evidence.  It is further trite that suspicion alone is not enough to destroy the employment relationship.

In the DHL-matter the LAC held that polygraph evidence is not an “approved type of evidence” and quoted with approval from the judgment in FAWU obo Kapesi & others v Premier Foods Ltd t/a Blue Ribbon Salt River (2010) :

“At best, the polygraph could be used as part of the investigation process to determine wherever or not a further investigation into the conduct of a particular individual is warranted.”

This means that polygraph test results can only be used to corroborate direct evidence. When used on its own, it amounts to no more than an opinion that there was some deception in answering often broadly phrased questions in a situation where a full context is not provided.

While most employment contracts are silent on the question as to whether an employee may be subjected to a polygraph test, some specifically require an employee to undergo such a test.

The question, then, is whether the employee’s signature on that contract constitutes his written consent and whether the employer can then demand that the employee takes a polygraph?

That question recently arose in the matter of Kgwedi v Bidvest Protea Coin (Pty) Ltd (December 2018).

The employee, a security guard, was required by the client to be polygraphed. The result showed “deception” which meant that he failed the test.

Although he had agreed in writing that he could be dismissed, he thereafter claimed that his dismissal was unfair.

The court accepted that the employee signed a contract stating that he was required to undergo a polygraph test at the behest of a client, and that it was binding on the parties.  If he failed, the employer could “commence with operational requirements procedures” which provided the rationale for removing the employee from that site and terminating his services.

Having failed, the employee entered into a settlement agreement with his employer in terms of which he was dismissed.  The court accepted that the employee knew and understood the agreement, and that he entered into it on a voluntary basis.

His dismissal was accordingly upheld.

The importance of this judgment

This judgment emphasises that the inclusion of a polygraph clause in a contract of employment – and the consequences if the employee fails that test – is binding on the parties. If, however, there is no such clause in the contract, an employer cannot compel an employee to take a polygraph test.