Unfortunately, there is no published research in South Africa to test the validity and reliability of polygraph examinations, and one has to rely on research conducted in the USA.

The American Polygraph Association’s library boasts with 80 research projects that, collectively, analysed and dissected well over 6,000 polygraph examinations. In summary:

Twelve studies probed the validity of 2,174 field examinations and showed that examiners’ results were accurate 98% of the time.

Eleven studies focused on independent analysis of 1,609 field examinations that have been corroborated by other evidence and found that on average, 92% of these examinations were reliable.

By far the most research has been conducted under laboratory conditions. In total there are 57 known research papers evaluating polygraph examination validity and accuracy under controlled laboratory conditions. It is generally accepted that during tests conducted under laboratory conditions, the interviewee experiences less ‘fear of detection’ stress, as the risks are known not to be real. This makes detection of dishonesty or withholding of information more difficult for the examiner. Nevertheless, even under laboratory conditions the polygraph examination still proves to be an effective investigative tool. The studies conducted under laboratory conditions include:

Some 41 studies involving 1,787 simulations of polygraph examinations which showed that on average, the outcome of the examinations were 80% accurate.

A further 16 laboratory bound studies involving 810 simulated polygraph examinations focused on reliability and found that 81% of examinations to be reliable.

Ultimately, the efficacy of a polygraph examination as a forensic tool is dependent more on the skills and experience of the examiner than on the polygraph equipment that monitors the examinee’s physiological responses to the examination. After all, monitoring changes in the respiratory system, galvanic skin response and the cardiac system are tried and tested technologies. Instead, the quality of the examination depends mostly on the ability of the examiner to compose the appropriate battery of questions and his or her ability to interpret the examinee’s physiological responses to them.

At present there are no laws governing the administering of polygraph examinations nor are polygraph examiners governed by a professional body.

PSSA examiners are affiliated to the American Polygraph Association (APA) as well as the Polygraph Association of South Africa (PASA) and South African Professional Polygraph Association (SAPPA).

By law, employees cannot be compelled to submit to a polygraph examination, although the employer may, with just cause, exert some pressure on employees to undergo a polygraph examination.

Refusal by an employee to submit to a polygraph examination may not be regarded as implying guilt, but it can be regarded as an aggravating factor when there is other evidence of misconduct.

Polygraph examiners have been accepted as expert witnesses whose evidence ‘needed to be tested for reliability’. The onus rests with the Commissioner to determine the admissibility and reliability of the results of the polygraph examination. The polygraph examination cannot be used to prove guilt, but may be regarded as an aggravating factor when there is other evidence of misconduct.

Where voluntary confessions are obtained as the result of a polygraph examination, the courts have tended to hold the confessions as valid.

IN EVIDENCE
Although the polygraph examination does not in and of itself provide definitive evidence in the way that a fingerprint, DNA sample or other physical evidence does, it does assist an investigation by casting or dispelling doubt and evincing further avenues of investigation.

IN THE EYES OF THE LAW
Polygraph examinations do not have a defined status in the eyes of the law, but there are numerous examples where the courts, including the CCMA have allowed polygraph examinations as corroborating evidence.

JUST CAUSE
It is generally accepted that employers may use polygraph examinations to investigate specific incidents where:

Employees had access to the property where the incident occurred
There are reasonable grounds or suspicion that the employee was involved in the incident
There has been economic loss or injury to the employer’s business.
Polygraph examinations may also be justifiably called for when the employer is combating:

Dishonesty in positions of trust
Serious substance abuse
Fraudulent behavior
Fraud in the form of deliberate falsification of documents.