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Deceptive or effective? Polygraph testing in the workplace

April 2014

Spiralling criminal activity in the workplace has seen the use of polygraph testing increase dramatically. Currently, despite there being no legislation regulating the use of the test by employers, it is often used as a pre-employment or pre-screening method.

"Polygraph" is a term used to describe a device that simultaneously measures and records physiological activities or electro-physiological activity. This data includes an individual's blood pressure, heart rate, respiration rate and skin conductance (perspiration). The device is essentially utilised to record a person's body reaction to the fear of being caught lying. 

The theory behind polygraph testing is based on the assumption that physiological activity in the human body increases when a person is lying and the polygraph is used to detect that deception.  Polygraph testing in the workplace is said to be highly contentious and controversial, as the admissibility and reliability of its results remain unclear.  However, polygraphists have been accepted as expert witnesses whose evidence needs to be tested for reliability.  Polygraphists are usually called to testify on how the test was administered, his/her qualifications, the type of test used and the questions asked. 

In NUMSA obo Mkhonza & Others v Assmang Chrome Machadodorp Works  the employer, Assmang Chrome, subjected all the stores' personnel to a polygraph test.  The applicant's employees had failed the test and were subsequently dismissed.  The arbitrator in this matter held that polygraph tests are inadmissible as evidence only if the examiner is not qualified or did not testify, or if the employees refused to be tested.  In the circumstances that the examiner testifies and the employees agree to undergo the tests, there is no basis to reject the results of the polygraph test. 

Legality of Polygraph Testing

The Constitution protects the fundamental rights of individuals against unlawful search and seizure, self-incrimination and invasion of privacy.  It provides for a general right to privacy, ”Everyone has the right to privacy”, and protects against specific infringements of privacy, such as search and seizures, and this infringement is triggered only when the right to privacy is invaded.  The scope of the right to privacy has to be demarcated with respect to the rights of others and the interests of the community.  It has been argued in some jurisdictions, therefore, that the right to privacy yields when the employer can demonstrate a sufficient interest. 

The employer may well argue that the need to protect property outweighs an employee's right to privacy in the context of a polygraph examination.  It has also been argued that by consenting to take a polygraph test, the employee voluntarily gives up his or her right to privacy.  Where undergoing the polygraph test is voluntary, there can be no invasion of privacy.  Consent must be in writing and the individual needs to be informed that the testing is voluntary.  Only questions discussed prior to the examination may be used and he/she has a right to have an interpreter present or, should he/she prefer, another person may also be present during the examination.  There may be no abuse, discrimination or threats.   

Employers are entitled to use polygraph testing to investigate specific incidents where:

  • employees have had access to the employer's property that is subject to an investigation;
  • the employer has suffered some sort of economic loss such as theft of company property;
  • there is suspicion that an employee was involved in such an incident;
  • the employer is trying to deal with dishonesty of employees who occupy positions of trust; and 
  • for purposes of investigating syndicate or fraudulent behaviour in the workplace. 

The results of a polygraph test cannot alone be used to interpret guilt of an employee.  It may be regarded as an aggravating factor to be considered in conjunction with other evidence of misconduct.  

In Mncube v Cash Paymaster Services (Pty) Ltd it was held that the applicant had consented to the polygraph test, and consequently concerns about privacy and free will do not arise in this case”.

Dismissal as a result of Polygraph Test results?

In SATAWU v Khulani Fidelity Security Services (Pty) Ltd it had been agreed between the employer and the trade union that employees would undergo regular polygraph tests and, if they refused to do so or failed them, it would not be unfair to terminate their employment based on operational requirements.  Davis JA accepted that the dismissal of the appellant employees on this basis was substantively and procedurally fair. The requirements of section 189 of the LRA had been complied with and the employees had failed to accept reasonable alternative offers of employment. 

In FAWU v Premier Foods Ltd  Basson J held as follows in relation to polygraph test results: "In the context of a disciplinary process the polygraph can be a useful tool in the investigation process but can never substitute the need for a disciplinary hearing.  A polygraph test on its own cannot be used to determine the guilt of an employee.  In the context of an arbitration, the results of a polygraph test 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 recognisable standards." 

In the arbitration of DHL Supply Chain (Pty) Ltd v De Beer NO & Others , the arbitrator noted that the result of a polygraph test is but one evidentiary fact that, on its own, cannot prove guilt.  The arbitrator considered all the evidence presented by the company and found that, if the results of the polygraph tests were excluded, the balance of the evidence was not sufficient to support a finding that the employees had been involved in the theft of stock.  The arbitrator therefore found the employees' dismissal to be substantively unfair and ordered their reinstatement.  On review the Labour Court agreed with the arbitrator that polygraph results on their own could not be used to determine the guilt of an employee.  This has consistently been the approach of our courts.

The latest Labour Court decision of Sedibeng District Municipality v SA Local Government Bargaining Council & Others dealt with the use of polygraph testing as a tool in considering promotions.  The essence of the dispute was whether the municipality was entitled to rely on the polygraph test results to disqualify the employees for appointment in circumstances where they would otherwise have been promoted based on their interview scores. 

The court agreed with the municipality that polygraph testing may be used as a legitimate assessment tool in considering promotions.  However, having considered authority on the use of polygraph testing, the court was of the view that exclusive reliance on polygraph test results to eliminate candidates for appointment on the basis of their deceitful character, in the absence of any other information placing a question mark over their integrity, was unfair.  The court was accordingly satisfied that the municipality committed an unfair labour practice relating to promotion by relying exclusively on the results of polygraph tests to determine the honesty of the employees. 

Accordingly, on its own, a polygraph test is not conclusive proof of an employee's guilt.  At best the polygraph can be used as part of the investigation process and can be taken into account where other supporting evidence is available.

International Regulation 

In 1998, the United States promulgated the Employee Polygraph Protection Act.  The Act prohibits pre-employment polygraph testing except where it is:

  • used to aid investigations of incidents involving economic loss or injury to the employers business;
  • used in investigations involving theft, loss or diversion if the employer is involved in the manufacture, storage, or distribution of controlled substances;
  • used in pre-employment screening where the employers primary business is the provision of certain types of security services, where the employee in question is employed specifically to safeguard sensitive businesses, assets or intuitions; and
  • used in pre-employment screening where employers are involved in the manufacture, storage, or distribution of controlled substances and the employee will have direct access to such controlled substances.

It has been argued that a similar piece of protective legislation needs to be promulgated in South Africa as both public and private sectors have engaged the application of polygraph testing to extract confessions from employees and dismiss those who refuse to take the test. 

What is evident from the case law discussed above is that polygraph testing may be lawfully utilised by employers as a tool to either conduct investigations into an event such as theft, dishonesty or misconduct, or narrow candidates for promotions.  However, the accuracy and reliability of these tests are controversial and the results alone cannot provide conclusive evidence and may not be used by an employer to dismiss an employee; this would constitute an unfair dismissal.

The team

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