Polygraph tests in the workplace

Can an employer dismiss an employee if he fails a lie detector test?

The Labour Appeal Court dealt with this issue in DHL Supply Chain (Pty) Ltd v De Beer No and Others (2014) (LAC), where it held that the mere fact that an employee fails a polygraph test is not in itself sufficient to find an employee guilty of dishonesty. The onus rests on the employer to lead expert evidence to prove the polygraph test’s cogency and accuracy.

The Labour Court had to consider this issue in Goldplat Recovery (Pty) Ltd v Commission for Conciliation Mediation and Arbitration & Others (26 January 2021). A syndicate stole gold concentrate worth approximately R850,000. Goldplat subjected each of the employees who worked in a restricted area to a polygraph test. Only one Maziya failed the test and was subsequently charged with misconduct and ultimately dismissed. Maziya referred an unfair dismissal dispute to the CCMA, where the Commissioner found his dismissal to be unjust and awarded him maximum compensation. The Commissioner found no direct evidence that implicated Maziya, and the assumption made by Goldplat that he was guilty by failing his polygraph test, was mere speculation.

Goldplat took the finding on review to the Labour Court.  The Court had to decide if a reasonable decision-maker on the same material facts would have made the same finding as the Commissioner.

In dealing with the polygraph tests’ reliability, the Labour Court referred to the DHL Supply Chain case. It found that as Goldplat failed to call an expert witness and relied only on the polygraph result to establish Maziya’s guilt, it upheld the Commissioner’s findings and dismissed the review application with costs. 

Employers should be wary of relying on polygraph tests when they intend to use these tests to discipline and ultimately dismiss an employee who fails the test. The sole reliance on failed polygraph tests will be insufficient to prove that an employee is guilty of misconduct or has lied. A polygraph test can only be relevant if it corroborates any other evidence that demonstrates that an employee is guilty of misconduct.