There is uncertainty and confusion as to whether polygraph test results are admissible in our labour law or not, and if they are, whether or not they carry sufficient weight to dismiss an employee based on a negative outcome of the testing of an employee.
Perhaps to begin the discourse, it is important to define what polygraph testing is. Polygraph is a term which literally means “many writings”. The term refers to a device that simultaneously measures and records selected psychological activities or electro-physiological activity. The device captures the minimum of three types of psychological data, usually differential blood pressure, heart-rate, respiration rate, and skin conductance.
In essence, this means the person being examined will fear being caught lying and his body will react reflecting that fear, which reactions are captured by the polygraph test.
The Unites states of America have enacted the Employee Polygraph Protection Act to regulate the usage of the polygraph tests in employment law. There are twenty other jurisdictions that have enacted similar legislations.
What weight do polygraph tests carry? It is important to understand that polygraph tests can never be used as primary evidence in finding an employee guilty of an offence. Polygraph tests are secondary evidence, meaning they are supporting evidence. They are used as further evidence to prove on a balance of probabilities that, for instance, the employee has stolen from their employer in support of evidence already provided which could be a video footage for instance which shows a person who looks strikingly like the accused employee.
It is interesting to see how the courts and the CCMA have dealt with polygraph testing. In Mahlangu v CIM Deltak (1986) 7 ILJ 346 (IC) the Industrial Court held that a voice analysis test administered by an unregistered psychologist was unscientific, invalid, unethical and unlawful.
The approach to polygraph evidence by commissioners is varied as some find the results unreliable and therefore inadmissible as evidence, others disregard the evidence if the polygraph examiner fails to submit his qualifications. It is important, therefore, that when presenting polygraph as evidence in disciplinary hearings, that the results are not merely presented but that the polygraph examiner is present and testifies on firstly, their experience and then the factors that they considered in reaching their finding on the results of the test.
In Sobiso and Others v Ceramic Tile Market (2000) 22 ILJ 811 (CCMA) it was held that the discharging of onus placed on the employer in terms of section 192 of the Labour Relations Act (the Act) is not discharged by sole reliance on a test result of a polygraph.
This further confirms my submission above that polygraph results can never be used as primary evidence. When used as primary evidence, I submit, polygraph testing is merely prima facie proof of guilt of the accused employee but it is not proof on a balance of probabilities which is the sufficient standard in employment law.
When used correctly as supporting evidence, the onus of proof placed on the employer in terms of section 192 of the Act is discharged and accordingly shifts to the employee to prove otherwise.
Employers are issued with a caveat not to readily resort to the usage of polygraph tests to secure guilty findings as such evidence is treated by the commissioners and the courts in great circumspect but should be used in issues relating to conducts that have elements of dishonesty.
I have observed on numerous instances where employers have charged employees with gross negligence for the employees’ failure to conduct their duty with the required care and skill expected of them and employers use polygraph testing to prove negligence.
The usage of polygraph in the above example is substantively flawed as in proving negligence; there is no element of deception required or some kind of dishonesty. One can never be negligent in that they lied for example. The culpability of the employee in an offense of negligence is on the employee’s failure to exercise reasonable care expected of them which is not found in conducts involving moral turpitude such as dishonesty and theft.
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