Probably one of the most challenging duties of an astute and well-meaning line manager, officiating as initiator or management representative in a disciplinary matter, is to present a case to a decision maker (presiding officer) in such a way that the latter is able to arrive at a disciplinary decision which is based on the truth.
Invariably, the line manager, officiating as decision maker in the matter, is faced with two opposing versions of the truth, while each of the opposing parties claim their particular version to be the truth. The veracity of the evidence presented in support of these opposing versions of the truth will eventually be determinant, leading the decision maker to a justifiable conclusion.
The veracity of the evidence depends on its credibility and reliability, which the decision maker has to assess and determine. The conclusion so reached is then incorporated his/her reasoned finding regarding guilt or innocence in respect of the charge.
Where it so happens that the evidence is not that clear-cut or obvious to endorse any of the two versions of the truth and where the two versions seem, on face value at least, equally balanced, the initiator of the case concerned may have to rely on other less conventional methods or devices in order to tilt the scale in favour of the prospective guilty finding he/she aspires to.
When the initiator reaches this seemingly “stalemate” situation, it is often the assistance of lie detector tests that could potentially come to the rescue.
The question now arises to what extent lie detector tests can legally and fairly be applied in the process of uncovering the truth in a disciplinary investigation and what is the probative value of lie detector tests?
In order to answer these questions, one has to firstly identify the lie detector tests which are commonly in use.
Notably, the most well-known lie detectors are the polygraph test (measuring blood pressure and perspiration during the inquest) and the voice stress analysis (detecting subtle, but significant fluctuation in voice tones and patterns during the inquest).
Both of these detection mechanisms have the objective to identify and expose deception on the part of the subject of the inquest. I will, in this communiqué, predominantly and generally refer to “lie detectors”, as generic terminology, without specifying a particular device, unless when quoting from a particular piece of case law. The principles mentioned in this communiqué will equally apply to polygraph tests, voice stress analysis tests, or, for that matter, to all other kinds of lie detector devices.
The statutory provisions contained in labour law do not specifically deal with the use of lie detectors, hence the “law” concerning the utilisation of lie detectors has to be found in relevant case law.
Which criteria govern the utilisation of lie detector tests, as gleaned from relevant case law?
Unless a provision is built into the employment contract, contractually obliging the employee to undergo a lie detector test as and when so required by the employer, the employee has to formally agree to be submitted to a lie detector test, each and every time such test is to be administered.