Polygraph-testing in employment

The thought crossed my mind: "How reliable is polygraph-testing ('Lie Detector Test') in the employment environment in the South African context?

With the prevalence of crime in the workplace such as misconduct, theft, fraud, sexual harassment and other work- and employment relations-related matters, the Polygraph Institute of South Africa (Pisa) is of the opinion that polygraph-testing can be used as a tool to establish the truthfulness of employees

Polygraph testing is quite a new concept in South Africa, with reference to employment disputes. We have no legislation up-to-date to control the use / abuse of the test or to protect the right of the employee's regarding the tests.

The Constitution of South Africa prohibits a person to undergo a polygraph test, unless he or she consents to it in writing.

I came across a very important court case on the Internet: (Harmse v Rainbow Farms 1997 WE) where the Commission for Conciliation, Mediation and Arbitration of South Africa (CCMA) set a precedent in the South African labour law.  The finding in this case allowed for companies and businesses to use polygraph-testing in the workplace in a responsible and sensible way.

The Labour Relations Act (Item 7a of Schedule 8) requires an employer to prove, on a balance of probabilities, that the alleged employee was actually involved in or guilty of misconduct.

Polygraph-testing is not the only tool to rely on when disciplining employees.  In other words, polygraph-testing cannot lead to the dismissal of an employee.  There must still be a procedurally-correct disciplinary enquiry where the chairperson must wheigh the evidence submitted, mitigating and aggravating circumstances etc. and "apply his/her mind" regarding the outcome of the case. 

According to the Internet the polygraph-testing is not 100% reliable (most sources indicate a maximum of 96%).  Perhaps we should do some research on the validity and reliability regarding the accuracy of this tool in employment issues.