The interpretation and evaluation of scientific evidence and its presentation in a court of law is central both to the role of the forensic scientist as an expert witness and to the interests of justice. This book aims to provide a thorough and detailed discussion of the principles and practice of evidence interpretation and evaluation by using real cases by way of illustration. The presentation is appropriate for students of forensic science or related disciplines at advanced undergraduate and master's level or for practitioners engaged in continuing professional development activity.
The book is structured in three sections. The first sets the scene by describing and debating the issues around the admissibility and reliability of scientific evidence presented to the court. In the second section, the principles underpinning interpretation and evaluation are explained, including discussion of those formal statistical methods founded on Bayesian inference. The following chapters present perspectives on the evaluation and presentation of evidence in the context of a single type or class of scientific evidence, from DNA to the analysis of documents. For each, the science underpinning the analysis and interpretation of the forensic materials is explained, followed by the presentation of cases which illustrate the variety of approaches that have been taken in providing expert scientific opinion.
Table of Contents
Preface xvi
Part 1 1
1 An Introduction to the Admissibility of Expert Scientific Opinion 3
1.1 Admissibility, Reliability and Scientific Evidence 3
1.2 The Impact of the DNA Revolution 5
1.3 The Miscarriage of Justice 6
1.3.1 The United Kingdom 7
1.3.2 The United States 8
1.3.3 Canada 8
1.3.4 Australia 9
1.4 DNA Reveals Wrongful Convictions 9
1.5 The Causes of Wrongful Conviction 10
1.6 Unreliable Scientific Evidence 11
1.6.1 The Status and Expertise of the Expert Witness 11
1.6.2 The Expert is not Impartial 12
1.6.3 The Evidence was Wrong 13
1.6.4 Exaggerated Evaluation by the Expert 13
1.6.5 Unethical Behaviour 14
1.6.6 Human Error 14
1.6.7 Non-validated Methodology 15
1.6.8 Overconfidence in New Techniques 15
1.7 The Scientist and the Laboratory 16
1.8 Conclusions 17
References 17
Further Reading 18
2 Admissibility from the Legal Perspective 20
2.1 Admissibility, Relevance and Reliability of Evidence 20
2.2 Admissibility in the United States 22
2.2.1 Reliability and the Frye Test 22
2.2.2 Meeting the Frye Criterion: US v Stifel 1970 23
2.2.3 Admissibility and the Gatekeeper Role: The Daubert Test 23
2.2.4 The Daubert Trilogy 25
2.2.5 General Electric v Joiner 1997 25
2.2.6 Kumo Tire Company v Patrick Carmichael 1999 26
2.2.7 PostÂ]Daubert Hearings: US v Dennis Mooney 2002 26
2.3 Admissibility in Canada 27
2.3.1 R v Mohan 1994 27
2.3.2 R v Abbey 2009 29
2.3.3 R v Trochym 2007 29
2.4 Admissibility in Australia 30
2.4.1 R v Bonython 1984 30
2.4.2 Makita v Sprowles 2001 31
2.4.3 Dasreef Pty Limited v Hawchar 2011 31
2.5 Admissibility in England and Wales 32
2.5.1 R v Turner 1975 33
2.5.2 R v Gilfoyle 2001 33
2.5.3 R v Luttrell 2004 34
2.6 Conclusions on Admissibility 35
2.6.1 Relevance and Expertise 35
2.6.2 The Scientific Basis of the Opinion 35
2.6.3 Weight of Evidence 37
References 37
Further Reading 38
3 Forensic Science and the Law: The Path Forward 39
3.1 National and Legal Developments in the United States 39
3.1.1 Federal Rules of Evidence 40
3.1.2 Strengthening Forensic Science in the United States 2009 41
3.1.3 US Reference Manual on Scientific Evidence 43
3.2 National and Legal Developments in Canada 44
3.2.1 Legal Enquiries into Miscarriages of Justice 44
3.2.2 The Science Manual for Canadian Judges 45
3.3 National and Legal Developments in Australia 46
3.3.1 The Uniform Rules of Evidence 47
3.4 National and Legal Developments in England and Wales 48
3.4.1 Forensic Science on Trial 2005 49
3.4.2 The Law Commission Report 2011 49
3.4.3 The Royal Statistical Society Guides 51
3.4.4 HCSTSC Report Forensic Science 2013 52
3.4.5 UK Government Response (2013) to the Law
Commission Report 52
3.5 Conclusions 53
References 53
Further Reading 54
4 Scientific Opinion and the Law in Practice 56
4.1 Scientific Opinion and the Judicial System 56
4.1.1 Adversarial and Inquisitorial Systems of Justice 56
4.1.2 Scientific Evidence Within the Inquisitorial System 57
4.1.3 Inquisitorial Versus Adversarial 57
4.2 The Scientist in Court 58
4.3 The Role and Duties of the Scientific Expert Witness 59
4.3.1 Definitions of the Role 59
4.3.2 Duties and Responsibilities of the Expert Witness 60
4.4 Quality Control of Analysis and Opinion 61
4.4.1 An Australian Standard for Forensic Analysis 61
4.4.2 Regulation of Forensic Science in the United Kingdom 62
4.4.3 Codes of Conduct and Practice 62
4.4.4 Accreditation of the Expert 63
4.5 Conclusion 63
References 64
Further Reading 64
Part 2 65
5 Fundamentals of the Interpretation and Evaluation of Scientific Evidence 67
5.1 Analysis, Interpretation and Evaluation 67
5.2 The Role and Outcomes of Forensic Investigation 68
5.2.1 Investigative Forensic Science 68
5.2.2 Evaluative Forensic Science 69
5.3 Fact and Opinion 69
5.3.1 Categorisation of Opinions 70
5.3.2 Factual Opinion 70
5.3.3 Investigative Opinion 70
5.4 Expert Opinion and the Forensic Science Paradigm 70
5.4.1 Categorical Opinion 71
5.4.2 Posterior Probabilities 72
5.4.3 Explanations 73
5.4.4 Where Does this Take Us? 74
5.5 What are Propositions? 74
5.5.1 The Hierarchy of Propositions 74
5.5.2 The Importance of Activity Level 75
5.6 Competing Propositions in the Court 76
References 77
Further Reading 77
6 Case Studies in Expert Opinion 78
6.1 Case Study 1: Facial Comparison Evidence 78
6.1.1 The Crime and Conviction 78
6.1.2 Expert Evidence and Opinion 79
6.1.3 Opinion in Atkins 80
6.2 Case Study 2: EarÂ]mark Identification 81
6.2.1 The Crime and the Evidence 81
6.2.2 Interpreting the Evidence and Challenges to the Opinion 81
6.2.3 The Conclusion of the Appeal 83
6.2.4 Opinion in Dallagher 83
6.3 Case Study 3: Glass and Gunshot Residue 84
6.3.1 The Crime and Trial 84
6.3.2 Analysis and Interpretation of the Scientific Evidence 84
6.3.3 Propositions for Evaluation 85
6.3.4 Evaluative Opinion: Glass 86
6.3.5 Evaluative Opinion: GSR 86
6.3.6 Opinion in Bowden 88
6.4 Conclusions 88
References 88
Further Reading 89
7 Formal Methods for Logical Evaluation 90
7.1 Frequentist and Bayesian Approaches to Evaluation 90
7.1.1 The Frequentist Approach to Formulating Opinion 90
7.1.2 The Logical Evaluation of Evidence 91
7.1.3 The Debate on Formulating Opinion 92
7.2 The Likelihood Ratio Method 92
7.3 Expressing Opinion Through Likelihood Ratio 93
7.3.1 Statements of Evaluative Opinion 93
7.3.2 Likelihood Ratio and Verbal Equivalent Statements 94
7.4 Evaluation and Bayes’ Theorem 94
7.4.1 Bayes’ Theorem: Prior and Posterior Odds 95
7.4.2 Combining Likelihood Ratios 97
7.5 Prior Odds 97
7.6 Posterior Probabilities 99
7.6.1 Opinion and Posterior Probabilities 99
7.6.2 The Prosecutor’s Fallacy 99
7.7 Working Out Conditional Probabilities and Likelihood Ratio 100
7.7.1 Likelihood Ratio at Source Level 100
7.7.2 Likelihood Ratio at Activity Level 101
7.8 Conclusions 102
References 102
Further Reading 103
8 Case Studies in Probabilistic Opinion 104
8.1 People v Collins 1968 104
8.2 R v Michael Shirley 2003 105
8.2.1 A Logical Evaluation of Scientific Evidence 106
8.2.2 The Outcome of the Appeal 108
8.3 R v D J Adams 1996, 1998 108
8.3.1 The Crime and the Evidence 109
8.3.2 A Probabilistic Analysis of the Evidence: Prior Odds 109
8.3.3 The NonÂ]Scientific Evidence 110
8.3.4 The Scientific Evidence 111
8.3.5 Total Likelihood Ratio and Posterior Odds 112
8.3.6 The Appeals 113
8.3.7 Review of the Issues in R v D J Adams 114
8.4 The Defendant’s Fallacy: R v J 2009 115
8.5 Conclusion 116
References 116
Further Reading 116
9 Cognitive Bias and Expert Opinion 117
9.1 Cognitive Bias 117
9.2 Contextual Bias 118
9.2.1 Confirmation Bias 119
9.2.2 Expectation Bias 119
9.2.3 Motivational Bias 119
9.2.4 Anchoring 120
9.3 Other Sources of Bias 120
9.4 Fingerprint Examination: A Case Study in Bias 120
9.4.1 The Review of the Brandon Mayfield Case 2004 120
9.4.2 The Fingerprint Inquiry Scotland 2009 121
9.4.3 Bias Within Fingerprint Examination 121
9.5 Mitigating Bias 122
9.6 Mitigating Bias Versus Research on Traces 123
9.7 Conclusions 124
References 124
Further Reading 125
Part 3 127
10 The Evaluation of DNA Profile Evidence 129
10.1 DNA Profiling Techniques – A Brief History 130
10.2 Databases in DNA Profiling 131
10.2.1 Allele Frequency Databases 131
10.2.2 Identification Databases 131
10.3 Interpretation and Evaluation of Conventional DNA Profiles 131
10.3.1 Combined Probability of Inclusion (CPI) or Exclusion (CPE) 132
10.3.2 Random Match Probability (RMP) 132
10.3.3 Likelihood Ratio 133
10.4 Suspect Identification from a DNA Database 133
10.4.1 The Frequentist Interpretation 133
10.4.2 The Likelihood Ratio Approach 134
10.4.3 Database Search Evidence in Court 134
10.5 Case Studies of DNA in the Court 135
10.5.1 R v Andrew Philip Deen 1994 135
10.5.2 Issues Raised by Expert Opinion in R v Deen 136
10.5.3 R v Alan Doheny 1996 138
10.5.4 The Doheny Trial 138
10.5.5 The Doheny Appeal 139
10.5.6 R v Gary Adams 1996 140
10.5.7 Challenges to the Interpretation of DNA Profiles: US v Shea 1997 141
10.6 Current Practice for Evaluating DNA Profile Evidence 142
10.6.1 The Impact of Doheny and Adams in the United Kingdom 142
10.6.2 Current Practice in the United Kingdom 144
10.6.3 Current Practice in Australia 145
10.7 DNA – The Only Evidence 146
10.8 Errors and Mistakes in Forensic DNA Analysis 147
10.8.1 Adam Scott 2012 147
10.8.2 R v S 2013 148
10.8.3 Laboratory Error Rates Versus the RMP 148
10.9 Conclusions 149
References 149
Further Reading 150
11 Low Template DNA 151
11.1 Technical Issues 151
11.1.1 Terminology 151
11.1.2 Samples 152
11.1.3 Technical Issues in Interpretation 152
11.1.4 Quantitative Evaluation in LTDNA Profiles 153
11.2 Importance of the Chain of Custody: Queen v Sean Hoey 2007 154
11.3 The Caddy Report 2008 155
11.4 Case Studies in LTDNA opinion in the UK Courts 156
11.4.1 Partial Profiles 156
11.4.2 Quantities of DNA; Interpretive Issues on Transfer 157
11.4.3 Very Low Quantities of DNA 159
11.4.4 Opinion Without Statistics 160
11.4.5 Experts Differ in Opinion 162
11.5 LTDNA in Jurisdictions Outside the United Kingdom 163
11.5.1 United States 164
11.5.2 Australia 165
11.6 Conclusions 167
References 167
Further Reading 168
12 Footwear Marks in Court 169
12.1 The Analysis and Interpretation of Footwear Marks 169
12.2 Match Opinion: R v D S Hall 2004 170
12.2.1 The Crime and the Evidence 170
12.2.2 Footwear Mark Evidence and Opinion 171
12.2.3 Review of Expert Opinion in R v Hall 172
12.3 The Likelihood Ratio Approach to Evaluation of Footwear Marks 172
12.4 Standardising Scales for Expert Opinion 173
12.4.1 SWGTREAD Scales of Opinion 173
12.4.2 ENFSI Scales of Opinion 175
12.5 Challenges to Opinion on Footwear Evidence: R v T 2010 175
12.5.1 Outline of the Footwear Mark Evidence in R v T 176
12.5.2 The Expert Witness’ Notes 177
12.5.3 Evaluation Using an Alternative Database 179
12.5.4 The Summary by the Appeal Court Judge 179
12.6 Discussion of R v T 180
12.6.1 Terminology, Probabilities and Statistical Methodology 180
12.6.2 Footwear Databases 181
12.6.3 Was the Jury Told the Basis of the Expert Opinion? 182
12.6.4 The Appeal Court Ruling: Bayes, Mathematics and Formulae 183
12.7 Footwear Mark Evidence After R v T: R v South 2011 184
12.7.1 The Crime and Evidence 184
12.7.2 Evaluation of the Footwear Evidence 184
12.7.3 Review of the Expert Opinion 185
12.8 ENFSI Recommendations on Logical Evaluation 2015 186
12.9 Conclusions 187
References 187
Further Reading 188
13 Fingerprints and FingerÂ]Marks – Identifying Individuals? 189
13.1 Fingerprint Identification on Trial 189
13.2 ACEÂ]V: A Scientific Method? 190
13.3 Evaluation Criteria 191
13.3.1 Thresholds for Categorical Evaluation 191
13.3.2 The Balthazard Model 192
13.3.3 Identification Thresholds and the Points Standard in the United Kingdom 192
13.3.4 The Basis of the NonÂ]Numeric (Holistic) Approach 193
13.3.5 Identification Thresholds in Other Jurisdictions 194
13.3.6 R v Buckley 1999 194
13.4 Evolution of the Basis of Fingerprint Opinion in the Court 196
13.5 A Critical Summary of Fingerprint Identification 198
13.6 Challenges to Fingerprint Testimony 198
13.6.1 R v P K Smith 2011 198
13.6.2 Shirley McKie and the Scottish Fingerprint Inquiry 1997–2011 200
13.7 Identifying a Mark from a Database 202
13.7.1 AFIS Versus Manual Systems 202
13.7.2 The Madrid Bombing Case (Brandon Mayfield) 2004 203
13.8 Admissibility of Fingerprint Evidence 204
13.8.1 US v Byron Mitchell 2004 204
13.8.2 US v Llera Plaza 2002 205
13.9 Towards a Probabilistic Evaluation of Fingerprint Evidence 206
13.10 Conclusions 208
References 208
Further Reading 209
14 Trace Evidence, Databases and Evaluation 210
14.1 Analytical Methodologies for Glass, Fibres and GSR 210
14.1.1 Glass Analysis 211
14.1.2 Fibre Analysis 211
14.1.3 GSR Analysis 211
14.2 Databases for Source and Activity Levels 212
14.2.1 Source Level 212
14.2.2 Activity Level 212
14.2.3 Glass 213
14.2.4 Fibres 213
14.2.5 GSR 213
14.2.6 Statistical Models and Case PreÂ]Assessment 214
14.3 Glass Evidence in Court 214
14.3.1 R v Abadom 1983 214
14.3.2 R v LewisÂ]Barnes 2014 215
14.3.3 R v L and Others 2010 216
14.3.4 People v Smith 2012 216
14.3.5 Review of the Evaluation of Trace Glass Evidence 217
14.4 Fibre Evidence in Court: R v Dobson 2011, R v Norris 2013 218
14.4.1 Fibre Evidence: Dobson 219
14.4.2 Fibre Evidence: Norris 220
14.4.3 Review of the Evaluation of the Fibre Evidence 221
14.5 Gunshot Residue (GSR) Evidence in Court 222
14.5.1 R v Wooton and Others 2012 222
14.5.2 R v Gjikokaj 2014 224
14.5.3 Review of the Evaluation of GSR Evidence 225
14.5.4 R v George 2007 226
14.6 Conclusions 227
References 227
Further Reading 227
15 Firearm and ToolÂ]Mark Evidence 229
15.1 Pattern Matching of Mechanical Damage 229
15.2 The Interpretation and Evaluation of ToolÂ]Mark Evidence 230
15.2.1 US Opinion 230
15.2.2 UK Opinion 232
15.3 Critical Review of ToolÂ]Mark Evaluation 232
15.4 Consecutive Matching Striations 234
15.5 Databases 234
15.6 ToolÂ]Marks and Evaluation by Likelihood Ratio 235
15.7 Firearms Evidence in the US Courts 236
15.7.1 United States v Hicks 2004 236
15.7.2 United States v Darryl Green et al 2005 237
15.7.3 US v Glynn 2008 240
15.8 Concluding Comments on Firearms Cases 241
References 241
Further Reading 242
16 Expert Opinion and Evidence of Human Identity 243
16.1 Introduction to EarÂ]Marks 243
16.2 R v Kempster 2003, 2008 244
16.2.1 The First Appeal 2003 245
16.2.2 The Second Appeal 2008 245
16.2.3 Conclusions From R v Kempster 246
16.3 State v Kunze 1999 247
16.3.1 The Frye Hearing 247
16.3.2 The Trial 248
16.3.3 The Appeal 249
16.4 Review of EarÂ]Mark Cases 249
16.5 Introduction to BiteÂ]Mark Evidence 250
16.6 The ABFO Guidelines and Expert Opinion 250
16.7 BiteÂ]Mark Cases in the United States 251
16.7.1 People v Marx 1975 252
16.7.2 The Appeal 252
16.7.3 State v Garrison 1978 253
16.7.4 State v Stinson 1986 254
16.7.5 BiteÂ]Mark Testimony in the Courts 255
16.8 Body Biometrics: Facial Mapping and Gait 255
16.8.1 R v Hookway 1999 255
16.8.2 R v Otway 2011 256
16.9 Conclusion 257
References 257
Further Reading 258
17 Questioned Documents 259
17.1 Handwriting and Signature Comparison – A Scientific Methodology? 260
17.2 Scales of Expert Opinion 261
17.3 Jarrold v Isajul and Others 2013 263
17.3.1 Dr Strach’s Testimony 264
17.3.2 Mr Holland’s Testimony 264
17.3.3 Mr Lacroix’s Testimony 265
17.3.4 The Appeal Court Judge’s Conclusion 265
17.4 Gale v Gale 2010 266
17.4.1 ESDA Analysis 267
17.4.2 Signature Analysis 267
17.5 The Bridgewater Four (R v Hickey and Others) 1997 268
17.5.1 Molloy’s ‘Confession’ 269
17.6 R v Previte 2005 270
17.7 Admissibility and Other Issues in Handwriting and Signature Evidence 271
17.8 Admissibility and Evaluation in the US Courts 272
17.8.1 US v Starzecpyzel 1995 272
17.8.2 US v Velasquez 1995 274
17.9 Conclusions 275
References 275
Further Reading 276
18 Bloodstain Pattern Analysis 277
18.1 The Nature of Bloodstain Pattern Evidence 277
18.2 Issues for BPA Expert Opinion in the Courts 278
18.2.1 The Scientific Basis of BPA 278
18.2.2 Who is the Expert? 279
18.2.3 The Courts’ and Lawyers’ Knowledge of BPA 280
18.2.4 The Evaluation and Significance of BPA Evidence 280
18.3 The Scientific Basis of Bloodstain Pattern Analysis: The Murder of Marilyn Sheppard 281
18.4 Three Approaches to the Presentation of Blood Evidence 282
18.4.1 Activity and Propositions: R v Thompson 2013 283
18.4.2 No Expert Testimony: R v White 1998 283
18.4.3 Reconstructing Activity as a Narrative: R v Hall 2010 284
18.5 The Problem of Expirated Blood 285
18.5.1 R v O’Grady 1995, 1999 286
18.5.2 R v Jenkins: The Trial and First Appeal 1999 287
18.5.3 R v Jenkins: The Second Appeal (2004) and
Two More Retrials 289
18.6 Experts in Disagreement: R v Perlett 2006 289
18.7 Conclusions 291
References 291
Further Reading 292
19 Conflicting Expert Opinion: SIDS and the Medical Expert Witness 293
19.1 Eminent Experts: Issues and Conflicts 293
19.2 R v Clark 2000, 2003 294
19.2.1 The Testimony of Meadow 295
19.2.2 The Second Appeal 2003 297
19.3 A Bayesian Analysis: Murder or SIDS? 298
19.3.1 Pr(H2) – The Probability of Two SIDS Deaths in the Same Family 298
19.3.2 Pr(H1) – The Probability of Two Murdered Infants in the Same Family 299
19.3.3 The Posterior Odds 299
19.4 R v Cannings 2004 300
19.5 Trupti Patel 2003 302
19.5.1 The Rib Fracture Evidence 302
19.5.2 The Judge’s Summing Up 303
19.6 Conclusions 304
References 304
Further Reading 305
Appendix: Some Legal Terminology 306
Index of Cases, Individuals and Inquiry Reports 307
General Index 309
