In the case of Mustek Ltd v Tsabadi NO & Others the Labour Court heard a case of dismissal based solely on polygraph test results.
If an employee is dismissed, after a disciplinary hearing was held, based on polygraph test results, the question arises whether such dismissal was fair.
Substantial fairness must prevail, meaning that all the facts / evidence of the case must be properly entertained (holistic view) by the presiding officer in a disciplinary hearing. A polygraph does not directly measure deception or lying. Instead it relies on the examiner drawing an inference from the physiological activity that it records.
At best it will remain a factor to be considered alongside other evidence. Further evidence will always be needed in addition to polygraph results which will only ever be regarded as supporting of other evidence of misconduct.
The test used by the presiding officer is one of a preponderance of probabilities and thus the evidence / facts placed before him / her should point circumstantial to the guilt of the employee (thus should be linked to the guilt of an employee) i.e.:
• The employee worked on the day of the theft;
• The employee were among a group of three employees who had access to the stock;
• The stock had a high street value, etc.
A polygraph examination should form part of the investigative process, perhaps narrowing down suspects and identifying witnesses or evidence.
The court confirmed that the results of polygraph tests alone are not enough to justify an employee’s dismissal. There should at least be other circumstantial evidence to confirm the polygraph test result before a person can be dismissed.