Expert evidence: Recommendations for future research

• Jurisdiction: South Africa
• Citation: (2006) 19 SACJ 276
• Published date: 16 August 2019
• Date: 16 August 2019
• Pages: 276-302
• Author: Lirieka Meintjes-Van der Walt

276

Expert evidence: Recommendations

for future research

LIRIEKA MEINTJES-VAN DER WALT*

ABSTRACT

The National Prosecuting Authority (NPA) requested the South African

Unit for Expert Evidence and Forensic Skills, based in the Faculty of Law at

Rhodes University, to undertake a collaborative research project ‘Science

for Prosecutors’. The present author was consultant to this project, the

major contributor and editor of the f‌inal report. This article outlines the

focal points of the research project mentioned above and summarizes the

recommendations which f‌lowed from the research undertaken. The f‌irst f‌ive

chapters of the report provide an overview of the law within which science

must be integrated. The following chapters deal with a range of expert

evidence — from syndrome evidence, DNA evidence, f‌ingerprinting evidence,

forensic investigation by examining computers and the use of behavioural

evidence in sentencing. After a review of the entire report, the present author

has formulated 14 recommendations for future action and further research

projects, which may be seen as the essence of this article.

Introduction

The National Prosecuting Authority requested the South African Unit for

Expert Evidence and Forensic Skills, based in the Faculty of Law at Rhodes

University, to undertake a collaborative research project ‘Science for

Prosecutors’.1 This article outlines the emphasis of the research project

and summarizes the recommendations which f‌lowed from the research

undertaken.

As humankind continues into the highly scientif‌ic and technological 21st

century, there can be no doubt that expert evidence in its different f‌ields

and manifestations will increasingly inf‌luence legal decision-making.

The term ‘expert evidence’ includes a range of opinion evidence.

This evidence, in turn, can vary greatly in its probative value, weight

and purpose. The term ‘expert evidence’ is used throughout this article

to denote certain kinds of specialised, systematised knowledge not

usually possessed by non-specialized magistrates and judges or by legally

trained or lay assessors. In this context the term includes the physical

sciences such as chemistry, physics and biology; the social sciences such

* B Juris LLB (UPE) LLM (Rhodes) D Juris (Leiden) Adjunct Professor of Law, University of

Fort Hare.

1 The present author was consultant to this project, the major contributor and edited the

f‌inal report.

(2006) 19 SACJ 276

© Juta and Company (Pty) Ltd

Expert evidence: recommendations for future research 277

as psychology, sociology, criminology and economics; and technical

sciences such as engineering, statistical analysis and computer science.

In this investigation, expert evidence also includes information offered

by persons who regard themselves as scientists, for example, experts in

certain f‌ields of forensic science such as ballistics and f‌ingerprinting. It is

also wide enough to include those witnesses who have become expert as

a result of their experience or skills.

The ever-developing f‌ields in which expert evidence can be used,

challenge both lawyers and judicial off‌icers. Specif‌ically in the case of

criminal courts where guilt must be proved beyond reasonable doubt,

prosecutors need to have the wherewithal with which to present, cross-

examine and argue on matters that require the introduction of an expert

to the dispute. The objective of this Report was not to train prosecutors

as scientists, but to empower them to become informed users of science.

The Research Report ‘Science for Prosecutors’ was formulated with this

goal in mind and was designed and organised to acquaint prosecutors with

knowledge of scientif‌ic methodology which can be used in respect of all

expert evidence. Certain scientif‌ic f‌ields which may present particular

problems were dealt with separately.

The f‌irst f‌ive chapters of the report provide an overview of the law

within which science must be integrated. These chapters are devoted to

general topics of law and science and serve to introduce issues that occur

during the pre-trial and trial processes of criminal justice proceedings.

Expert evidence involves the meeting and mixing of two distinct

professional worlds, those of law and science. The remaining chapters

are therefore dedicated to specif‌ic categories of expert evidence. A dual

approach is thus followed: both the legal relevance of the particular f‌ield

of expertise, as well as the state of the science underlying the expert

testimony, are discussed.

This research investigation examines four broad categories of expert

evidence applicable to criminal cases:

(i) DNA evidence as representing ‘real’ science which deals with

empirical methods appropriate to resolution by normal scientif‌ic

methods and where the scientif‌ic research was not specif‌ically

developed for forensic reasons;

(ii) syndrome evidence representing the more controversial behavioural

and psychological evidence where the ‘cause’ may commonly

be constructed partly from the symptoms themselves and the

application of behavioural science in the sentencing phase;

(iii) traditional forensic science methods specif‌ically developed for

forensic purposes such as f‌ingerprint evidence, ballistics and

disputed documents; and

© Juta and Company (Pty) Ltd