Is polygraph testing in employment disputes reliable?

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01 Apr 2021

A polygraph test, or more frequently called a lie detector test is a test used to verify a person’s truthfulness via a series of questions posed to the individual undergoing the test. In short, a polygraph test records a number of different bodily responses which may then be used to determine whether someone is telling the truth or lying. The test usually measures things like blood pressure, changes in a person’s breathing and sweating on palms.

Is there any law regulating the use of polygraph testing in South Africa

Polygraph testing is a fairly old concept in South Africa, especially in disputes relating to employment law. There has never been nor is there presently any labour or employment legislation which regulates or controls the use of the test, or which protects the employee’s right against the abuse of the test by an employer seeking to dismiss or punish an employee.

Can an employee be forced to undergo a polygraph test at work?

It is against the Constitution of South Africa to compel a person to undergo a polygraph examination, unless she or he consents to it. The consent must be in writing and usually forms part of the employment contract agreed upon between the employer and employee.

When is the employer permitted to use the polygraph?

Commonly, if the employment contract states so, employers usually use polygraph testing to investigate specific incidents, inclusive but not limited to:

  • Employees having access to the employer’s property which is the subject of some or other investigation;
  • There is a reasonable suspicion that an employee was involved in an incident of misconduct;
  • The employer has suffered economic loss or injury to the employer’s business or property, such as theft of company property and the employer suspects the employee of being involved;
  • The employer is investigating serious alcohol, illegal contraband or narcotics abuse and / or fraudulent behaviour within the employer’s business and suspects the employee of either partaking or having knowledge thereof.

What is the status of a polygraph test at the CCMA?

Polygraphists have been accepted as expert witnesses at the CCMA or relevant Bargaining Council whose evidence needs to be tested for reliability. The duty of the Commissioner is to determine the admissibility and reliability of the evidence. Polygraph tests may not be interpreted as guilt but may be regarded as an aggravating factor especially where other evidence of misconduct exists and is probable. It must be noted that polygraph test results, on their own, are not a basis for a finding of guilt.

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(This article is provided for informational purposes only and not for the purpose of providing legal advice. For more information on the topic, please contact the author/s or the relevant provider.)
Fadia Arnold

Fadia Arnold was admitted as an Attorney of the High Court of South Africa in 2011 after completing two years of article clerkship. She obtained her Bachelor of Social Sciences... Read more about Fadia Arnold


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