Craig D. Adam - Forensic Evidence in Court: Evaluation and Scientific Opinion

1. Chapter 07
2. Chapter 12
3. Chapter 13
4. Chapter 17
5. Chapter 19

1. Chapter 02

CRAIG ADAM

This edition first published 2016
2016 John Wiley & Sons, Ltd

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Library of Congress CataloginginPublication Data

Names: Adam, Craig.
Title: Forensic evidence in court: evaluation and scientific opinion / Craig Adam.
Description: United Kingdom : John Wiley & Sons, 2016. | Includes bibliographical references and index.
Identifiers: LCCN 2016012014 (print) | LCCN 2016012473 (ebook) | ISBN 9781119054412 (cloth) | ISBN 9781119054429 (pdf) | ISBN 9781119054436 (epub)
Subjects: LCSH: Evidence, ExpertMethodology. | Forensic sciences. | Evidence, ExpertHistory.
Classification: LCC K2283 .A935 2016 (print) | LCC K2283 (ebook) | DDC 347.73/67dc23
LC record available at https://lccn.loc.gov/2016012014

A catalogue record for this book is available from the British Library.

This book is about how science and scientific opinion impinge upon and influence legal debate. It is written by a scientist, principally for an audience of scientists, more specifically for those in the later stages of an undergraduate degree in forensic science, studying at postgraduate level or working as practitioners. As such, a basic understanding of the discipline and of technical matters relating to evidence examination and analysis is assumed, although relevant science is recapped and expanded upon where appropriate. The context throughout is the court of law. Legal cases from across jurisdictions, including principally those based on the AngloAmerican legal system, are used to demonstrate the evolution of expert opinion, to illustrate the difficulties faced by the scientists and the legal professionals and to provide a real world backdrop to material intended for exposition and discussion in the lecture room.

Although this book is an educational text and not a research monograph, this field of study is subject to developments and advances from both the professional and academic spheres. It is relevant therefore to include some discussion of the scholarship that underpins professional practice and, more specifically, I have incorporated recent research that seeks to resolve current difficulties and may impact directly on expert testimony in the future.

To meet the aims of this text the material is organised within three sections. The first serves the dual purpose of setting the scene, by reviewing the impact of forensic science in the courts over the past thirty years, as well as providing the overall context within which methods for interpretation and evaluation of scientific evidence have been and continue to be developed. This is followed by five chapters in which the focus centres on the forensic scientist as expert witness and ways in which scientific opinion may be formulated from the interpretation of experimental findings, particularly through logical evaluation by likelihood ratio; this includes discussion of many of the issues around the delivery of such opinion.

The final section presents scientific opinion in the context of evidence types. Starting from full DNA profiles where quantitative approaches are informed by rigorously derived databases, the discussion moves to other types of evidence such as footwear marks, glass and fibres where the interpretation may be more qualitative and the associated databases more open to challenge. Later chapters deal with evidence such as handwriting and bloodstain pattern analysis where opinion is formulated much more in accordance with the experience of the individual expert and indeed where the members of the court may believe they can achieve their own evaluation by reviewing the evidence for themselves.

I am very grateful to Dr Ian Evett CBE and Mr Mike Allen for reading and commenting on draft sections of this text. I trust that I have been able to use their feedback to improve the accuracy and clarity of the discussion but the final responsibility for that, of course, must rest with me. I also wish to thank my wife, Alison, for her invaluable advice, patience and support throughout the development and writing of this book.

Craig Adam,
January 2016

The investigative and legal processes, from the discovery of a crime to the verdict of the court, should ultimately ensure that the guilty person is correctly identified and that the innocent are exonerated. However, in many cases, the complexity, both of these processes and of the contributions to the debate, may lead to difficulties and challenges that act to impede and divert both scientific and legal arguments and which may lead to an unsatisfactory outcome. This book is concerned principally with the contribution of scientific evidence to legal debate. Central to this is an understanding of how the scientists findings can be properly interpreted, evaluated and communicated to the court and how the court draws appropriate inferences from the expert opinion in reaching its decision on the ultimate issue. In doing so, the court must necessarily be satisfied that the science is valid and the evidence relevant to its deliberations.