You’d be forgiven if a scene from Law & Order flashed through your mind if you are asked to take a lie detector test in the workplace.

All of a sudden, you are picturing yourself in a depressing, tiny room, hooked up to a machine that’s being monitored by an austere man who keeps looking up from his spectacles, which are perched on the tip of his nose. You are being interrogated like someone suspected of committing a serious crime.

Ok, well that’s a little dramatic, but an employer asking an employee to take a polygraph test in South Africa is a possibility. Basically, it’s meant to form part of a dispute resolution process, and employers might make use of these tests to minimise risk, financial loss and general damage to the company. However, there are a lot of misconceptions around using lie detector tests in the workplace. Therefore, it’s essential for employees to know their rights so that they are not unfairly treated at the office.

I’ve never heard of this… what is a lie detector test?

A lie detector test, aka a polygraph test, is a process in which someone is hooked up to a device that monitors and measures physiological factors such as blood pressure, pulse, breathing patterns, perspiration and cardiac responses to a series of questions. The idea is that these responses will determine whether or not someone is being truthful while answering certain questions. The person facilitating and recording the process is known as a polygraphist (remember the intimidating man in tv shows we mentioned at the beginning?).

How does this apply to a working environment?

An employer will brief a polygraphist on what to ask an employee who is suspected of misconduct while carrying out their duties. The questions must be framed is such a way that only “yes” or “no” answers are possible. The polygraphist will then monitor the employee’s physiological responses to the answers given. It will, ultimately, help determine whether or not an employee is being truthful.

A report of the session is then compiled by the polygraphist and handed over to whoever is authorised- a manager, for example- to view it.

This sounds very intense- are lie detector tests legal in South Africa?

While there is no specific legislation in place regulating the use of polygraph tests, an employer can ask an employee to take one, but it must be voluntary (we’ll go into more detail just now). However, no one can be forced to undergo a lie detector test, as it is against the Constitution. Not only could an improperly imposed lie detector test violate workers’ rights to fair labour practices, it could also infringe on their rights to inherent dignity, privacy, freedom and physical security. What’s more, the Constitution also states that people have to right to not be subjected to medical or scientific experiments without consent.

In which circumstances would it be appropriate for an employer to ask an employee to take a lie detector test?

Employers should only really use polygraphs tests as a part of the investigation into any wrongdoing- it cannot be the only investigative tool.  Essentially, it is meant to help identify and narrow down employees who may be guilty and collect any other relevant info.

Generally speaking, it would be reasonable for an employer to make use of a polygraph test if:

  • There is a reason to believe an employee was involved in an incident that broke company rules or the law
  • An employee had access to property that is currently under investigation
  • Company property has been stolen or there has been financial loss or damage to the business.
  • An employer has reason to believe that there is dishonesty in the workplace
  • There is enough reason to believe that an employee is abusing a substance and it’s affecting their work and colleagues
  • An employee is suspected of committing fraud.

Requirements for a legal lie detector test in the workplace

In order to comply with what the Labour Relations Act deems as fair, a polygraph test in the workplace must not be used unfairly against a single employee or group of employees; must be applied neutrally to all employees; and must be conducted by a professional using proper equipment to ensure it’s scientifically valid and accurate as possible.

Again, it must be said that the result of a polygraph test can only be used as supporting evidence.


Employees cannot be forced to take lie detector tests.

Under no circumstances can an employee be coerced or bullied into taking a polygraph test. The employee must give consent in writing.

What’s more:

  • The employee must be made aware of the fact that the test is voluntary
  • Only questions discussed BEFORE the test will be asked during it
  • The polygraphist is the only person who is allowed to ask the questions
  • The employee is entitled to have an interpreter in the room if needed
  • The employee is not allowed to be abused or threatened during the test.

If I fail a lie detector test, will I be fired?

There are many misconceptions about lie detector tests in the workplace. If an employee “fails” a polygraph test, they cannot be fired based solely on that fact; the results aren’t necessarily 100% accurate. The outcome of a lie detector test can only be used in conjunction with other evidence to justify the dismissal of a worker. It’s been reported that some employers work in penalties into employees who do not pass lie detector tests contracts; however, based on cases, the CCMA sees that as an unfair labour practice in South Africa.

Repairing a fraught working relationship

Being asked to take a lie detector test at work means your employer may have had reasons to believe you were involved in some form of misconduct at work. Of course, this can be emotionally traumatic. Also if you pass a test, what does that mean for your relationship with your employer?

If your boss doesn’t take the lead here, you could suggest having a follow-up meeting to discuss the implications and the way forward. Transparency and honesty are critical in this case. You have to have an open talk about why the trust broke down, and what processes must be put in place to avoid a similar situation in future.

We’ve got your back!

LAW FOR ALL has expert legal advisers who can assist you if you need legal advice after being asked to take a lie detector test in the workplace. What’s more, we can help with referring a case to the CCMA. Read more about our affordable policy options and join now.