'N REGSVERGELYKENDE STUDIE VAN DESKUNDIGE GETUIENIS IN STRAF- EN SIVIELE VERHORE

• Main Author: Knoetze, Izette
• Other Authors: Prof CP van der Merwe Fick
• Format: Others
• Language: en-uk
• Published: University of the Free State 2008
• Subjects: Criminal and Medical Law
• Online Access: http://etd.uovs.ac.za//theses/available/etd-08152008-133702/restricted/

Progress in the field of science requires more and more the use of experts as witnesses during legal proceedings. It is due to the complex nature of some scientific principles that legal practitioners make use of expert witnesses to answer their questions and to supply them with reasons for their answers as well. Due to their expertise and/or experience, expert witnesses are in a position to explain to the courts complex concepts and to help the courts in their understanding and interpretation of scientific principles. Courts, however, have a discretion to reject evidence by expert witnesses should the court be of the opinion that such evidence is irrelevant and unreliable or if the witness failed to substantiate, to the satisfaction of the court, the reason for his or her opinion. The report of the expert witness contains an exposition of the reasons on which he or she basis his or her opinion. The report has the further use that it affords the court a chance to subject it to cross-examination. Aspects on which expert witnesses may testify is legion. Examples discussed above include among other things evidence regarding deoxyribonucleic acid testing on blood samples taken from a victim of crime, evidence extracted by means of a polygraph test, evidence regarding fingerprints, earprints, brain fingerprinting and thermal imaging. Evidence by psychologists and psychiatrists is an important aid should a court, for example, have to decide on the custody and access of minors after divorce. Interception and/or tapping of cellular and/or telephone conversations is a relatively simple and fast way to obtain evidence during the investigation of an alleged offence. In this regard, the Bill of Rights calls for a weighing of interests of the right to privacy (of the accused) and the public interest (the maintaining of law and order). Legislation regulates most matters concerning expert evidence. Case law should provide guidelines to the courts in their evaluation of expert evidence. If an expert witness presents evidence regarding an unknown scientific technique to the court, the courts should look to international case law for guidance. American case law laid down principles that should be met before evidence regarding an unknown scientific technique is presented in court and may serve as guidelines to South African courts. Factors such as the reliability and acceptance of a technique in scientific circles both play a role in the adjudication of the question concerning the admission and/or rejection of evidence as far as that technique is concerned.