EMMA MCBRIDE
FORENSIC DNA ANALYSIS:
A POSITIVE RESULT OR A NEGATIVE OVER RELIANCE?
LLB LAW HONOURS
FRIDAY 13TH APRIL 2012
I hereby declare that this dissertation is my own work entire, that no part of it consists
of the work of others, except where this is acknowledged, and that no part of it has been
published.
Signed: Emma
McBride
Dated: 12.04.2012
i
ABSTRACT
The focus of this research is in the area of forensic DNA analysis and whether there
exists, in the criminal justice system, too heavy or simplistic a reliance on the results of
DNA profiling, which could lead to miscarriages of justice. The first chapter examines
the reliability of DNA evidence. The second chapter examines the scientific
interpretation of the results of DNA evidence. The third chapter examines the lay person
interpretation of DNA results. The main conclusions drawn from this thesis are that
reform is required in the field of forensic DNA evidence and caution is required at all
stages of the criminal justice system, to ensure that DNA profiling is not relied upon in
an overly-simplistic manner which could lead to miscarriages of justice.
ii
ACKNOWLEDGEMENTS
The writing of this dissertation has been one of the most significant academic
challenges I have ever had to face. I offer my sincerest gratitude to my supervisor, Dr
Rhonda Wheate, whose encouragement, supervision and support from the preliminary
to concluding level of this thesis has enabled me to develop a greater understanding of
the subject.
iii
Table of Contents
INTRODUCTION ....................................................................................................................... 1
THE SCIENCE OF DNA ...................................................................................................... 2
FORENSIC DNA ANALYSIS ............................................................................................. 3
THE ADVANTAGES OF DNA PROFILING ..................................................................... 4
THE FIRST DNA EXONERATION CASE ......................................................................... 5
INNOCENCE PROJECTS.................................................................................................... 7
CONCLUSION ..................................................................................................................... 8
CHAPTER 1: THE RELIABILITY & ADMISSIBILITY OF DNA EVIDENCE ............... 9
THE RISKS OF LCN DNA ................................................................................................ 10
LCN DNA RESULTS: THE DIFFICULTY OF INTERPRETATION .............................. 11
LCN DNA: PUBLIC CONCERNS..................................................................................... 13
THE LEGAL ADMISSIBILITY OF DNA EVIDENCE .................................................... 17
CONCLUSION ................................................................................................................... 22
CHAPTER 2: THE SCIENTIFIC INTERPRETATION OF DNA EVIDENCE ................ 24
DIFFERENT MODES OF PRESENTING RESULTS....................................................... 24
UNIVERSAL STANDARDS AND BEST PRACTICE ..................................................... 26
CONCLUSION ................................................................................................................... 28
CHAPTER 3: THE LAY INTERPRETATION OF DNA EVIDENCE ............................... 30
SCIENTIFIC EVIDENCE & THE JURY .......................................................................... 31
‘WHITE COAT SYNDROME’ .......................................................................................... 32
THE ‘CSI EFFECT’ ............................................................................................................ 34
CONCLUSION ................................................................................................................... 35
CHAPTER 4: CONCLUSIONS & RECOMMENDATIONS............................................... 37
REFERENCE LIST………………………………………………………..………………….42
iv
INTRODUCTION
The introduction of DNA analysis into the legal realm in the mid 1980’s
“revolutionised forensic science”.1 The technique has made possible both apprehension
of criminals and exoneration of those wrongly convicted.2 Forensic analysis of DNA
excites a great deal of public interest and has been described as “the most powerful
investigative tool since the advent of fingerprint analysis…”3 To begin with, this thesis
will discuss the advantages of DNA analysis and the positive effects which it has been
seen to have on a number of cases which have been revisited since its introduction, and
where DNA analysis has proved crucial in the exoneration of those wrongly convicted.
In doing so, this thesis will also consider the impact of Innocence Projects and their role
in utilising DNA to rectify miscarriages of justice.
In the decades since its introduction, DNA analysis has proved itself to be a valuable
and beneficial tool.4 However as the technique expands and develops, so too do the
dangers associated with it. One such danger is ‘the CSI effect’ which has been described
as “… the perceptions of the near-infallibility of forensic science in response to the TV
show”.5 The remainder of this thesis will consider the dangers of DNA analysis in order
to determine whether there is too much of a heavy or simplistic reliance on the results of
DNA which could lead to new miscarriages of justice.
1
John M. Butler, Forensic DNA Typing: Biology, Technology and Genetics of STR Markers (Academic
Press: 2nd edition, 8 Feb 2005) at 2.
2
David R. Keller et al., Ethics in Action: A Case Based Approach (Wiley-Blackwell, 19 Dec 2008) 454.
3
Todd W Bille, DNA analysis: A Powerful Investigative Tool’, Indiana State Police Laboratory (1999)
<http://www.promega.com/~/media/Files/Resources/Profiles%20In%20DNA/302/DNA%20Analysis%20
A%20Powerful%20Investigative%20Tool.ashx> Accessed 23 October 2011.
4
Jonathan M. Finn, Capturing the Criminal Image: From Mug Shot to Surveillance Society (University of
Minnesota Press, 21 Oct 2009) 68.
5
Kelly Pyre, Forensic Science under Siege: The Challenges of Forensic Laboratories and the MedicoLegal Investigation System (Academic Press; 1 edition, 12 April 2007) 306.
1
THE SCIENCE OF DNA
DNA, or deoxyribonucleic acid, is the genetic blueprint for all living things. 6 Almost
every cell in the human body contains DNA, which encompasses the biological
instructions that render each species unique.7 DNA is made up of four bases: A, T, C &
G which are put into a combination to form a gene.8 Genes are protected by a
chromosome which wraps the gene up in a protective layer of protein. 9 Each human
contains on average 3 million bases, 20,000 genes and 46 chromosomes.10 Each person
inherits half of their chromosomes from their mother, and the other half from their
father.11 The human Y chromosome is the sex determining chromosome (an XX
chromosome indicates a female and an XY chromosome indicates a male).12 There are
two types of DNA; DNA which can be found in the nucleus (Nuclear DNA) and DNA
which can be found in the mitochondria (Mitochondrial DNA).13 Testing of the latter
can establish immigration patterns because it is a clear record of maternal inheritance;
however it is the former that is most commonly used for forensic testing.14
6
Martin Egli et al., Nucleic Acids in Chemistry and Biology (Royal Society of Chemistry; 3rd Revised
edition, 31 Aug 2005) 210.
7
Russell P J, et al., Biology Volume 1: The Dynamic Science (Brooks/Cole; 2nd edition (1 Oct 2010) 3.
8
Gennaro F. Vito, et al., Criminology: Theory, Research and Policy (Jones and Bartlett; 3rd Revised
Edition (6 May 2011) 91.
9
Mollie F Hayes, et al., DNA and Biotechnology (Academic Press; 3rd Edition (6 Nov 2009) 197.
10
Dorling Kindersley, The Concise Human Body Book: An Illustrated Guide to its Structure, Function
and Disorders (Dorling Kindersley (1 Jun 2009) 34.
11
Helen Kreuzer, et al,. Molecular Biology and Biotechnology: A Guide for Teachers (American Society
for Microbiology; 3rd Edition (11 April 2008) 410.
12
Karthikeyan et al., ‘A database for Human Y chromosome protein data’ Bioinformation 4(5): 184-186
(2009) 184.
13
Lucian Gorgan ‘DNA – Source of Forensic Evidence’, International Journal of Criminal Investigation,
Volume 1, Issue 2 at 103.
14
John M. Butler, Fundamentals of Forensic DNA Typing (Academic Press; 1 edition, 13 Oct 2009) 383.
2
FORENSIC DNA ANALYSIS
DNA analysis or ‘DNA fingerprinting’ was first described in 1985 by Dr. Alec Jeffreys,
an English geneticist.15 Jeffreys discovered that DNA contained a number of sequences
that were repeated again and again.16 He then established that the number of repeated
sections varied in each individual, rendering their genetic make-up completely unique,
with the exception of identical twins.17 Jeffreys developed a technique which could
examine the variation of length in each of these DNA sequences which created the
ability to discern one person from another.18 The concept of testing DNA for the
purpose of human identification was then established.
DNA can be extracted from a variety of places such as blood, semen, bones and teeth.19
DNA analysis does not mean testing every single base of the DNA as this would be an
impossible feat.20 Instead scientists test a location in the DNA known as a locus.21 The
number of loci which will be tested varies from jurisdiction to jurisdiction.22
Since its first use in 1985, DNA analysis has developed scientifically following the
introduction of a number of sensitive and accurate scientific tools and techniques.23 One
such technique is Low Copy Number (LCN) DNA which has led to attempts to analyse
more difficult and challenging samples such as those containing DNA from only a few
15
Ibid at 4.
John M. Butler, Forensic DNA Typing: Biology, Technology and Genetics of STR Markers (Academic
Press: 2nd Edition, 8 Feb 2005) 2.
17
Ibid.
18
Salem Press, The Twentieth Century: Great Scientific Achievements (Salem Press Inc. (31 Dec 1994)
1062.
19
Brenda W. Lerner, World of Forensic Science: A-L (Thomson/Gale, 2006) 220.
20
Susan Petricevic (ESR) ‘DNA Profiling in forensic science’
<http://nzic.org.nz/ChemProcesses/biotech/12D.pdf> Accessed 31 October 2011.
21
Kelly Pyrek, Forensic Science under Siege: The Challenges of Forensic Laboratories and the MedicoLegal Investigation System (Academic Press; 1 edition, 12 April 2007) 306.
22
Keith Inman, et al., Principles and Practice of Criminalistics: The Profession of Forensic Science
(Protocols in Forensic Science) (CRC Press; 1 Edition (29 Aug 2000) 280.
23
Ajay Kumar, et al., Ethics and Policy of Biometrics: Third International Conference on Ethics and
Policy of Biometrics and International Data Sharing (Springer; 1st Edition. edition (23 April 2010) 27.
16
3
cells.24 Today, the sensitivity and discriminating power of forensic DNA analysis has
resulted in the science behind this important investigative technique becoming even
more sensitive (scientifically)25 and the public perception of it even more powerful.26
THE ADVANTAGES OF DNA PROFILING
Forensic DNA analysis has many advantages. Firstly, DNA evidence can be said to be a
more reliable form of evidence which is now widely accepted by the scientific
community.27 Prior to the use of DNA evidence in courts, eye witness testimony was
more heavily relied upon and this brought along with it inherent dangers.28 The MidAtlantic Innocence Project revealed that mistaken eyewitness identifications were a
factor in more than 70% of the initial 239 DNA exoneration cases.29 This is a huge
percentage which highlights the difficulties with relying on eyewitness identification as
a reliable source of evidence.
DNA analysis sought to relieve some of the problems which existed in the criminal
justice system at that time.30 An authoritative study on the forensic use of DNA noted
that; “...the reliability of DNA evidence will permit it to exonerate some people who
24
Coast, G. & Genetics, I., 2009. Extracting evidence from forensic DNA analyses : future molecular
biology directions. ‘Review Literature and Arts of the Americas’, 46(iii), p.339-40, 342-50.
25
William J Tilstone, Forensic Science: An Encyclopedia of History, Methods and Techniques
(ABC_CLIO Ltd (15 May 2006) 256.
26
John M. Butler., Forensic DNA Typing: Biology, Technology and Genetics of STR Markers (Academic
Press: 2nd edition, 8 Feb 2005) at x.
27
Shelton, Donald. Forensic science in court challenges in the twenty-first century, (Lanham, Md:
Rowman & Littlefield Publishers, 2011) 28.
28
Michael Bromby, et al. ‘An Examination of Criminal Jury Directions in Relation to Eyewitness
Identification in Commonwealth Jurisdictions’ Common Law World Review Vol. 36 (4), 303-336, 2007,
<http://gcal.academia.edu/MichaelBromby/Papers/9952/An_Examination_of_Criminal_Jury_Directions_
in_Relation_to_Eyewitness_Identification_in_Commonwealth_Jurisdictions > Accessed 02 November
2011.
29
Professor Gary Wells ‘Mistaken Eyewitness Identifications’ (Mid Atlantic Innocence Project, 2011)
<http://www.exonerate.org/www.exonerate.org/about-2/causes-of-wrongful-convictions/mistakeneyewitness-identifications/> Accessed 03 November 2011.
30
Ibid.
4
would have been wrongfully accused or convicted without it.”31
Secondly, DNA analysis can also be seen to be valid as it provides a scientific basis
which allows for a physical link to be made between a criminal and a crime scene in
order to secure a conviction.32 At the same time it also works to exclude suspects who
without it may be charged for a crime they did not commit.33 The validity of DNA
analysis is particularly clear in cases where DNA has been used to exonerate those
wrongly convicted.34
THE FIRST DNA EXONERATION CASE
Forensic use of DNA technology was first used to exclude a suspect in 1986 in the
English case of Colin Pitchfork35 which arose when two young girls were raped and
murdered in Leicestershire, in 1983 and 1986. The first murder was that of a 15 year old
school girl, Lynda Mann. Blood discovered at the scene was found to be blood type A
(which at that time amounted to a 10% match of the adult male population).36 Due to no
further leads and a lack of forensic evidence the police had no other option but to wind
down the investigation into the murder. Three years later in 1986 however, another 15
year old girl, Dawn Ashworth, was found raped and murdered in the same town.37 The
police were convinced that both murders had been committed by the same person.38
National Institute of Justice, ‘Convicted by juries, exonerated by science: Case studies in the use of
DNA Evidence to establish innocence after trial’ (1996) <https://www.ncjrs.gov/pdffiles/dnaevid.pdf>
Accessed 03 November 2011.
32
U.S. Congress, Congressional Record, V. 149, PT.1, Jan 07 2003 – Jan 17 2003 (United States
Congress (2006) 503.
33
Robert Bertino, Forensic Science: Fundamentals and Investigation (SWEP; 1 edition (7 Feb 2008) 160.
34
Ibid.
35
Susanne Elvidge (BSc Hons) ‘Forensic Cases: Colin Pitchfork, First Exoneration Through DNA’
(Explore Forensics, 2011) <http://www.exploreforensics.co.uk/forenisc-cases-colin-pitchfork-firstexoneration-through-dna.html > Accessed 04 November 2011.
36
Robert Bertino, Forensic Science: Fundamentals and Investigation (SWEP; 1 edition (7 Feb 2008) 160.
37
Alan Gunn, Essential Forensic Biology (Wiley-Blackwell; 2nd Edition (23 Jan 2009) 92.
38
Ibid.
31
5
Semen samples from the second murder also confirmed a match to the blood type of the
first.39 A local man then confessed to the murder of Dawn Ashworth, yet denied any
involvement in the first murder.40 Police consulted Jeffreys, who (as discussed above)
had developed a technique that could examine DNA profiles, in an attempt to verify that
the suspect was responsible for both of the murders.
In 1985, Jeffreys along with Dr Peter Gill and Dr Dave Werrett had been the first to
demonstrate that DNA could be lifted from stains left at a crime scene, a point which
proved vital in the case of Colin Pitchfork.41 DNA tests were conducted and were able
to establish that the suspect was not responsible for the murders. The police then
conducted a mass operation to obtain blood samples from 4,000 men in the area.
Initially, no matches were found, however, it was then discovered that Pitchfork had
made his friend give DNA on his behalf. His friend was later overheard discussing this
and Colin Pitchfork was arrested. His DNA was then found to be a match to the crime
scenes. This case was the first in the world to exonerate a suspect through the use of
DNA evidence. Jeffreys later said “I have no doubt whatsoever that he [the man who
had falsely confessed] would have been found guilty had it not been for DNA evidence.
That was a remarkable occurrence.”
42
Had it not been for the introduction of forensic
DNA profiling the real criminal, Colin Pitchfork, may never have been found and an
innocent person could have been wrongfully imprisoned.
39
Ibid.
Forensic Science Service ‘Colin Pitchfork Case Study’ <http://www.forensic.gov.uk/html/media/casestudies/f-18.html> Accessed 04 November 2011.
41
Barry A J. Fisher, et al., Introduction to Criminalistics: The Foundation of Forensic Science (Academic
Press (17 Feb 2009) 267.
42
Lincoln Bates, et al., ‘DNA Fingerprinting and Society’ (27 Aug 2008) <http://www.wpi.edu/Pubs/Eproject/Available/E-project-090408-022926/unrestricted/Lincoln_Kayla_Marisa_IQP_Final.pdf>
Accessed 10 November 2011.
40
6
INNOCENCE PROJECTS
Following the introduction of forensic DNA profiling, many non-profit legal
organisations known as Innocence Projects were set up, dedicated to using the new
technique to help exonerate those who had been wrongly convicted. Since their
introduction Innocence Projects have had a significant impact using DNA profiling to
rectify miscarriages of justice around the world.43 In the US alone there have been 275
post-conviction DNA exoneration cases since the first in 1989. 208 of these exoneration
cases have been since the year 2000. Out of the 275 exoneration cases, 17 of the people
served time on death row. Had it not been for DNA proving their innocence they may
not be alive today. The average prison sentence served by exonerates is 13 years and in
total the number of years served over all exoneration cases is approximately 3,564.44
The impact of Innocence Projects in utilising forensic DNA profiling in rectifying
miscarriages of justice speaks for itself upon reading the above statistics.
Yet another advantage of DNA analysis is that it is objective,45 in that the results are
completely factual.46 Unlike eyewitness testimony, there are no issues of personal
feelings or opinions involved in obtaining a result; instead it is based on scientific
processes which are able to produce profiles which can then be interpreted to determine
the likelihood of a match between a DNA sample found at the crime scene and the DNA
of a suspect.47
Michael Naughton, ‘Wrongful Convictions and Innocence Projects in the UK: Help, Hope and
Education’ (2006) Web Journal of Current Legal Issues
<http://www.familieslink.co.uk/download/july07/wrongful%20convictions%20innocence%20project.pdf> Accessed 10 November 2011.
44
Innocence Projects Inc. ‘Facts on Post-Conviction DNA Exonerations’
<http://www.innocenceproject.org/Content/Facts_on_PostConviction_DNA_Exonerations.php#>
Accessed 25 November 2011.
45
Ibid.
46
Ibid.
47
Ibid.
43
7
CONCLUSION
DNA analysis has proved itself time and again to be an extremely powerful scientific
tool which carries with it a great deal of general acceptance by both the scientific and
legal communities.48 At first instance forensic DNA profiling appears to be reliable,
valid and objective. This raises questions however: Just how heavy or simplistic a
reliance should there be on the results of DNA analysis, when so much is at stake
depending on the interpretation of the results given by the forensic scientist? Is there a
perception that DNA is almost infallible and conclusive in all respects? Should there be
a greater awareness of the dangers of over reliance or over-simplification of the
interpretation of DNA results, which could almost prove as dangerous and as unlawful
as a misidentification by an eyewitness? The remainder of this thesis will be dedicated
to addressing these issues in order to examine the dangers of an over reliance and oversimplification of forensic DNA profiling results.
48
Shelton, Donald. Forensic science in court challenges in the twenty-first century, (Lanham, Md:
Rowman & Littlefield Publishers, 2011) 28.
8
CHAPTER 1: THE RELIABILITY & ADMISSIBILITY OF DNA
EVIDENCE
The remarkable success of forensic DNA profiling has led to attempts to analyse more
difficult and challenging samples such as those containing DNA from only a few cells.49
This approach, known as Low Copy Number (LCN) DNA typing; ‘facilitates the
examination of a whole new range of evidence types that previously could not be
analysed because of the very low amounts of DNA recoverable from the sample’.50 In
general, LCN DNA testing refers to testing a sample which contains less than 100pg of
DNA.
Laboratories employ a number of techniques to do so such as increasing the
number of Polymerase Chain Reaction (PCR) cycles to improve the amplification field
from samples containing low levels of DNA. With increased cycles of PCR, samples
that were originally very small can then be copied so many times that they become able
to be analysed. The impact of LCN on the criminal justice system is significant and
likely only to increase in the future.
In recent years, a number of high profile cases have allowed the courts to express their
opinion as to the reliability, admissibility and evidential value of DNA evidence
obtained using the LCN process.51 The validity of LCN DNA has been a controversial
matter52 at least since R v Hoey53 in 2007 and more recently in R v Reed.54 This chapter
discusses the special considerations which are required to interpret the results of LCN
DNA given that it is impossible to tell where such a minute sample came from. In
49
Coast, G. & Genetics, I., 2009. Extracting evidence from forensic DNA analyses : future molecular
biology directions. ‘Review Literature and Arts of the Americas’, 46(iii), p.339-40, 342-50.
50
J. Buckleton and P. Gill, ‘Low Copy Number’ in J. Buckleton, C. Triggs and S. Walsh (eds), Forensic
DNA Evidence Interpretation (CRC Press: Florida, 2005) 276.
51
See R v Reed [2009] EWCA Crim 2698 and R v Hoey [2007] NICC 49.
52
Law Commission, ‘Low Copy Number (LCN) DNA revisited’ (CLW 2010, Issue No. 23 at 1)
Available
<http://www.gcnchambers.co.uk/gcn/areas_of_specialisation/areas/criminal_defence/criminal_law_updat
es/criminal_law_update_20_01_10> Accessed 10.12.2011.
53
R v Hoey [2007] NICC 49.
54
R v Reed [2009] EWCA Crim 2698.
9
particular, it is important to consider the implications of allele dropout and the
possibility of laboratory-based contamination.55 The remainder of this chapter will
consider the legal admissibility of expert opinion evidence and what is required for it to
be deemed admissible by the courts.
THE RISKS OF LCN DNA
The sensitive nature of the LCN DNA process is accompanied by a range of risks which
may lead to possible wrongful convictions and may also have the potential to mislead
criminal investigations.56 One such risk comes from the number of PCR cycles which
have to be considerably increased to obtain an LCN DNA profile.57 PCR is a common
technique to amplify a number of copies of a piece of DNA generating thousands to
millions of a particular DNA sequence.58 Increasing PCR cycles inevitably leads to a
magnified risk of contamination and inaccurate results caused from ‘stochastic
effects’.59 Stochastic effects occur predominantly when only a very small amount of
DNA is available to begin with,60 and materialise when random loci or alleles are
sampled more than others, leading to peak height imbalance and causing alleles to drop
out completely.61 The trouble is that it is difficult to tell which if any peaks are missing
or falsely present, and even if the sample was to be run through the machine a number
of times, the same result may not necessarily be produced each time - which can clearly
Peter Gill ‘Application of Low Copy DNA Profiling’ Croatian Medical Journal (CMJ) (2001)
42(3):229-232 at 229.
56
Michael Naughton et al, ‘The need for caution in the use of DNA evidence to avoid convicting the
innocent’ E. & P. 2011, 15(3), 245-257.
57
Ibid.
58
Esther Van Zimmeren et al, ‘A paper tiger? Compulsory license regimes for public health in Europe’
IIC 2011, 42(1), 4-40.
59
Michael Naughton et al, ‘The need for caution in the use of DNA evidence to avoid convicting the
innocent’ E. & P. 2011, 15(3), 245-257.
60
John M. Butler, Fundamentals of Forensic DNA Typing (Academic Press 2010) 331.
61
Andrei Semikhodskii, Dealing with DNA Evidence: A Legal Guide (Routledge-Cavendish; 1 Edition
(25 Jan 2007) 34.
55
10
lead to unreliable test results.62 This is a major problem with LCN, because the
cornerstone of good scientific method requires that results are reproducible.63 What this
means for a criminal case is that it may produce a result that is a whole or partial profile
that does or does not match the accused, but if the results cannot be produced reliably –
how reliable is it all?
Another risk accompanied with the LCN process is contamination. If the starting
amount of DNA is very small and there is also some contamination in it, if PCR is used
to multiply the sample – the contaminant is also multiplied.64 As the amount of crime
sample DNA decreases, the chance of contamination by other sources increases; the
DNA contamination will then be multiplied along with the suspects DNA.65 This then
becomes difficult (and sometimes) impossible to determine what DNA is from the
offender and what is contamination.66 Whereas if you had a large amount of DNA to
begin with, big peaks are evident in the DNA results and tiny contaminant peaks are
conspicuous and easily identifiable. The trouble with LCN is, all the peaks are tiny and
it becomes difficult to tell (scientifically) which are contaminants and which are real.67
LCN DNA RESULTS: THE DIFFICULTY OF INTERPRETATION
As a result of above risks, there are a number of difficulties associated with the
interpretations that can be drawn from LCN DNA results even if a DNA profile is
62
John M. Butler, Advanced Topics in Forensic DNA Typing: Methodology (Academic Press; 3rd Edition
(27 July 2011) 328.
63
Robert A. Day, How to Write and Publish a Scientific Paper, (Greenwood Press; 7th Revised edition
(16 Jun 2011) 63.
64
James E. Girard, Criminalistics: Forensic Science and Crime (Criminal Justice Illuminated) (Jones and
Bartlett Publishers, Inc.; 1 edition (1 Aug 2006) 387.
65
Ibid.
66
William C. Thompson, ‘The Potential for Error in Forensic DNA Testing (and how that complicates the
uses of DNA Databases for Criminal Identification’ (Aug 12, 2008)
<http://www.councilforresponsiblegenetics.org/pageDocuments/H4T5EOYUZI.pdf> Accessed
12.12.2011
67
Lawrence Kobilinsky, Forensic Chemistry Handbook (Wiley-Blackwell (3 Jan 2012) 308.)
11
accurately yielded.68 A phenomenon termed ‘adventitious transference’ can occur due to
the fact that an LCN profile can stem from the cells of a single touch which may have
originated from innocent interactions by individuals unrelated to the crime.69 This is
another significant pitfall due to the advances in technology that make it possible to
detect and test increasingly minute DNA samples.70 Thomson et al. (2003) highlight,
“Whereas the original DNA tests required a fairly large amount of biological material
to get a result (e.g. a blood stain the size of a dime), current DNA tests are so sensitive
that they can type the DNA found in samples containing only a few cells.”71
Although adventitious transfer cannot be strictly controlled, there are a number of ways
to minimise and account for such contamination including: improve sample collection
and if possible obtain a DNA sample from the normal user of an exhibit of interest or
the person who may have come into contact with the exhibit prior to the offence. 72 This
is very difficult in major crime scenes or scenes which are busy public places as there
are a number of ways to contaminate a crime scene. Contamination can take place if
someone sneezes, coughs or touches a part of their body and then touches the area
containing the sample to be tested.73 DNA left at a crime scene can also be subject to
environmental contamination such as exposure to heat, light and moisture which can
speed up degradation of DNA.74 As a result, not all DNA evidence may yield a usable
profile.
Overall, Gill (2001) noted three specific consequences of amplifying LCN DNA which
Michael Naughton et al, ‘The need for caution in the use of DNA evidence to avoid convicting the
innocent’ E. & P. 2011, 15(3), 245-257.
69
P. Gill, ‘Application of Low Copy Number DNA Profiling’ (2001) 42(3) Croatian Medical Journal
230 n.12 at 231.
70
Kelly Pyrek, Forensic Science under Siege: The Challenges of Forensic Laboratories and the MedicoLegal Investigation System (Academic Press; 1 edition, 12 April 2007) 96.
71
Ibid.
72
Van Oorschot et al. Investigative Genetics 2010, 1:14 at 11, available from
<http://www.investigativegenetics.com/content/1/1/14> Accessed 28 November 2011.
73
Aric W. Dutelle, An Introduction to Crime Scene Investigation (Jones and Bartlett Publishers, Inc (8
Mar 2010) 225.
74
Ibid.
68
12
can lead to inaccurate DNA profiles; (a) allele drop-out may occur because one allele
can be preferentially amplified; (b) stutters in the profile may be preferentially analysed
– sometimes referred to as false alleles; and (c) the method is prone to sporadic
contamination which occurs when alleles that are not associated with the crime stain or
sample are amplified.75 This could lead to complex or incomplete profiles, and
inaccurate interpretation of these profiles could lead to wrongful convictions. Even
worse, the extreme sensitivity of LCN increases the possibility of false forensic
inferences.76
LCN DNA: PUBLIC CONCERNS
The scientific controversy surrounding LCN DNA analysis rose to public attention77 in
the case of Sean Hoey.78 In August 1998, a car bomb exploded in a busy shopping
centre in the Northern Ireland town of Omagh, killing 29 people and injuring over 200
others.79 The bombing was described by the media as “the worst terrorist atrocity in
Northern Ireland’s history”.80 A key part of the trial involved LCN DNA analysis by
the Forensic Science Service (FSS) on pieces of the bomb timer and explosive wiring.81
Court Records state: “The evidence establishes that the arrangements within the police
in 1998 and 1999 for the recording and storage of items were thoroughly
P. Gill, ‘Application of Low Copy Number DNA Profiling’ (2001) 42(3) Croatian Medical Journal
230.
76
James Randerson, ‘We’ve now pushed the technology to the absolute limit’ (The Guardian, 16 Jan
2008) <http://www.guardian.co.uk/uk/2008/jan/16/ukcrime.forensicscience1> Accessed 05 Feb 2012.
77
S Krimsky and T Simoncelli, ‘Genetic Justice: DNA Data Banks, Criminal Investigations, and Civil
Liberties’ Columbia University Press (25 Jan 2011) at 176.
78
R v Hoey [2007] NICC 49.
79
John. M Butler, Advanced Topics in Forensic DNA Typing Methodology (Academic Press, 2011) at
315
80
Lesley Anne Henry, ‘Omagh bomb legal victory: The men behind worst atrocity of the Troubles’
Belfast Telegraph (Belfast, 9 June 2009) Available from <http://www.belfasttelegraph.co.uk/news/localnational/omagh-bomb-legal-victory-the-men-behind-worst-atrocity-of-the-troubles-14331399.html>
Accessed 01 December 2011.
81
John M. Butler, Advanced Topics in Forensic DNA Typing: Methodology (Academic Press; 3 rd Edition
(27 July 2011) 315.
75
13
disorganised.”82 The property store was described as “a complete mess.”83 There was
no universal system of logging items received, no proper recording in police stations so
no inventory of what was in a store room at a particular time – all of which significantly
increased the risk of contamination.
The trial lasted 56 days and was hinged on LCN DNA evidence 84 on the basis of an
apparent LCN DNA link between Hoey and a number of exhibits recovered from crime
scenes.85 When the trial concluded in December 2007, Mr Hoey was found not guilty of
all 58 charges brought against him.86 Even more significantly the judge - Justice Weir strongly rejected the evidence, raising significant concerns about the validity of the
LCN technique87 and also highlighting the careless handling of DNA throughout the
trial.88 Fundamentally, the DNA evidence was found not to have the necessary integrity
to be reliable due to the risk of it having been contaminated or interfered with. 89 In his
concluding observation Weir J emphasised the cardinal principle of criminal law
established in R v Steenson90; “Justice ‘according to law’ demands proper evidence…
“evidence which is so convincing in truth and manifestly reliable that it reaches the
standard of proof beyond reasonable doubt.”91 The evidence in Hoey failed to meet
such an immutable standard and accordingly Mr Hoey was found not guilty.
82
R v Hoey [2007] NICC 49 at 51.
Ibid at 52.
84
John. M Butler, Advanced Topics in Forensic DNA Typing Methodology (Academic Press, 2011) at
315
85
R v Hoey [2007] NICC 49.
86
John. M Butler, Advanced Topics in Forensic DNA Typing Methodology (Academic Press, 2011) at
315
87
Ibid.
88
Ibid.
89
Don Mathias, ‘Observations on LCN DNA Analysis’ (2010)
<http://donmathias.zoomshare.com/files/lcndna.pdf> Accessed 16 Feb 2012.
90
R v Steenson and others [1986] NIJB 17 at 36 per Lord Lowry CJ.
91
R v Hoey [2007] NICC 49 at 65.
83
14
This judgement raised considerable questions over the merits of LCN DNA testing and
led to a review of the technique.92 An interim suspension was placed on the use of LCN
DNA in criminal investigations in England and Wales93 while an internal review of ongoing cases involving the FSS and the LCN DNA technique was conducted by the
Crown Prosecution Service (CPS).94 The CPS concluded “that LCN DNA analysis
provided by the FSS should remain available as potentially admissible evidence”95 The
press release went on to state that “At present, there is no reason to believe that there is
any inherent unreliability in the LCN DNA analysis process provided that it is carried
out according to the prescribed processes, and that the results are properly interpreted.
In its work so far, the review has found nothing that would indicate any serious flaw in
the scientific principles.”96 The nature of the samples makes reproducibility a
significant problem for obtaining a consistent profile and for giving a reasoned
interpretation of what the results mean.
Following the judgement in Hoey, a review (known as the ‘The Caddy Review’) was
conducted into the low template DNA profiling techniques.97 The authors of the Caddy
Review state that “it is our opinion that LCN and LTD [NA] are extensions of the
internationally accepted process of standard DNA profiling”.98 The authors further
concluded that “reservations (with regard to the LCN technique) have been allayed
from a study of the raw data produced by the FSS, recent experimental work conducted
Karen Lotter, ‘Setback for LCN DNA’ (Forensic Science @ Suite 101, 22 Dec 2007)
<http://karenlotter.suite101.com/setback-for-lcn-dna-a38889> Accessed 20 Feb 2012.
93
Ibid.
94
Ibid.
95
CPS Press Release ‘Review of the use of Low Copy Number DNA analysis in current cases: CPS
Statement’, 14 January 2008, Available <http://www.cps.gov.uk/news/press_releases/101_08/> Accessed
02 December 2011.
96
Ibid.
97
B. Caddy, G. R. Taylor and A. M. T. Linacre, A Review of the Science of Low Template DNA Analysis
(2008), available at < http://www.homeoffice.gov.uk/publications/police/operationalpolicing/Review_of_Low_Template_DNA_1.pdf >, accessed 03 December 2011.
98
Ibid. at Section 7.2
92
15
by the FSS and also from detail information submitted by the other (UK) forensic
science providers which clearly demonstrate the soundness of LTDNA analysis
(including LCN) providing all the appropriate conditions are met”99 Emphasis was
once again placed on the importance of satisfying all the appropriate conditions and
ensuring that the LCN DNA analysis is carried out according to the prescribed
processes.100
The Caddy Review also chose to emphasise that “any LTDNA profile should always be
reported to the jury with the caveats: that the nature of the original starting material is
unknown that; the time at which the DNA was transferred cannot be inferred; and that
the opportunity for secondary transfer is increased in comparison to standard DNA
profiling”.101 The juror’s interpretation of DNA evidence is an issue which will be
discussed in more depth in subsequent chapters however; it is important to note the
emphasis placed on presenting an LTDNA profile to the jury in comparison to a
standard DNA profile. LTN DNA results must be interpreted cautiously and all factors
regarding the extreme sensitivity of the technique must be taken into consideration. The
Caddy Review gave the LCN DNA technique an apparent clean bill of health102
however the conclusions set out in the review have since attracted a great deal of
criticism103 and it would appear that there still exists a great deal of ambiguity with
regards to the general uses of the LCN DNA technique.104 There is a significant risk that
the Crown can read more into results of LCN than they should (i.e. to inculpate an
99
Ibid at Section 7.2
John. M Butler, Advanced Topics in Forensic DNA Typing Methodology (Academic Press, 2011) at
315
101
John. M Butler, Advanced Topics in Forensic DNA Typing Methodology (Academic Press, 2011) at
316 (Caddy et al, 2008 at Section 7.4)
102
Allan Jamieson, ‘LCN DNA Analysis: R. v Reed and Reed’ The International Journal of Evidence &
Proof, E. & P. 2011, 15(2), at 161.
103
J. Gilder, R. Koppl, I. Kornfield, D. Krane, L. Mueller and W. Thompson, ‘Comments on the Review
of Low Copy Number Testing. Letter to the Editor’ (2008) 23 Int J Legal Med 535.
104
Allan Jamieson, ‘LCN DNA Analysis: R. v Reed and Reed’ The International Journal of Evidence &
Proof, E. & P. 2011, 15(2), at 161.
100
16
accused person), given that they cannot specifically determine the source of the sample,
the extent of the contamination and transfer.
The English Court of Appeal has expressed its opinion as to the reliability, admissibility
and evidential value of low template DNA primarily that obtained using the LCN
process in the case of R v Reed.105 The judgement in this case deals with two main
issues. The first is the admissibility of LCN DNA as evidence.106 The second is whether
an expert witness should be permitted to provide an opinion on the LCN DNA evidence
on matters such as the likelihood and means by which the DNA may have been
transferred to the place of discovery.107 Overall, the judgement concluded that: “… a
challenge to the validity of the method of analysing Low Template DNA by the LCN
process should no longer be permitted at trials where the quantity of DNA analysed is
above the stochastic threshold of 100–200 picograms [with a picogram being one
trillionth of a gram] in the absence of new scientific evidence.”108 The judgement thus
sets a minimum standard for LCN DNA evidence as to what is required for the court to
deem it as a reliable form of scientific evidence.109
THE LEGAL ADMISSIBILITY OF DNA EVIDENCE
Given everything discussed about the scientific reliability of LCN, it is now imperative
to discuss the legal admissibility of this technique. The admissibility of scientific
evidence is an issue which has plagued the courts for a number of years,110 and one
105
R v Reed [2009] EWCA Crim 2698
Allan Jamieson, ‘LCN DNA Analysis: R. v Reed and Reed’ The International Journal of Evidence &
Proof, E. & P. 2011, 15(2), at 161.
107
Ibid..
108
R v Reed and Reed; R v Garmson [2009] EWCA Crim 2698 at [74], per Thomas LJ.
109
Michael Naughton et al, ‘The need for caution in the use of DNA evidence to avoid convicting the
innocent’ E. & P. 2011, 15(3), at 250.
110
Kaushal B. Majmudar (J.D., Harvard Law School, Class of 1994), ‘Daubert v. Merrell Dow: A
Flexible approach to the admissibility of novel scientific evidence’ Harvard Journal of Law and
Technology, Volume 7, Number 1 Fall 1993 at 187.
106
17
which The Court of Appeals of the District of Columbia addressed in Frye v United
States.111 The Court in Frye stated that “Just when a scientific principle or discovery
crosses the line between the experimental and demonstrable stages is difficult to
define… the thing from which the deduction is made must be sufficiently established to
have gained general acceptance in the particular field in which it belongs.”112 The Frye
test stated that any new evidence should be approved by the people who use it,113
however many questions remained unanswered after Frye: What types of evidence shall
be accepted? If accepted, what shall the purpose of it be? Who shall accept it? How
many experts constitute general acceptance?114 Despite the ambiguities in the exact
meaning of Frye, it was utilised by many courts in the 70 years after, in determining the
admissibility of novel scientific evidence.115 The first case to question Frye and the idea
that general acceptance in itself was sufficient for scientific evidence to be admissible,
arose in Daubert v Merrell Dow.116 In this case, the US Supreme Court ruled that the
trial judge was the “gatekeeper” to prevent “junk science” from entering the
courtroom.117 This gate keeping function of the court could be interpreted to suggest
that the court will be wary of sciences in order to prevent evidence with no scientific
basis from even entering the court. The US Supreme court in Daubert recognised
“general acceptance” as an important, rather than exclusive, factor in determining the
reliability of scientific evidence.118 The implication of this would be a higher standard
of test for determining what types of evidence are scientific which may be another step
111
Frye v United States (1923) 54 App DC 46, 293 F 1013, 34 ALR 1.
Ibid.
113
Stephen M. Patton, ‘DNA Fingerprinting: The Castro Case’ The Harvard Journal of Law and
Technology’, Volume 3, Spring Issue, 1990.
114
Ibid.
115
Kaushal B. Majmudar (J.D., Harvard Law School, Class of 1994), ‘Daubert v. Merrell Dow: A
Flexible approach to the admissibility of novel scientific evidence’ Harvard Journal of Law and
Technology, Volume 7, Number 1 Fall 1993 at 187.
116
Daubert v Merrell Dow Pharmaceuticals Inc (1993) 509 US. 579.
117
Daubert v Merrell Dow Pharmaceuticals Inc (1993) 509 US. 579.
118
David S. Caudill, ‘Expert Scientific Testimony in Courts: The Ideal and Illusion of Value-Free
Science’, The Panteneto Forum, Issue 39, July 2010.
112
18
in the right direction to prevent so-called “junk science” from entering the court room.
The court suggested that there are four factors to consider, now known as the “Daubert
factors”, they are; testing and validation, peer review, error rates, and lastly, the
traditional factor set out in Frye of general acceptance in the relevant scientific
community.119 In order to be deemed admissible, scientific evidence would need to
satisfy all of the above criteria. Daubert also placed increased emphasis on the overall
reliability of scientific evidence.120
In April 2009, the Law Commission published Consultation Paper 190, 'The
Admissibility of Expert Evidence in Criminal Proceedings in England and Wales: A
New Approach to the Determination of Evidentiary Reliability'.121 The Consultation was
elicited by a growing dissatisfaction with the state of the law relating to the admission
of expert evidence.122 The Commission were concerned that there exists a "pressing
danger" of wrongful convictions and acquittals123 and that the most recent miscarriages
of justice may be 'the tip of a larger iceberg'.124 The Commission identified their
proposal as the progeny of Daubert.125 The Commission, however, unlike Daubert,
proposed two sets of guidelines: one set of guidelines relate to scientific evidence and
the second to experience based testimony.126 The Commission proposed that expert
evidence would be admissible in criminal proceedings only if certain tests were met:
firstly the court must be satisfied that it would provide information which is likely to be
119
Daubert v Merrell Dow Pharmaceuticals Inc (1993) 509 US. 579.
Jessica M. Sombat, Latent Justice: Daubert's Impact on the Evaluation of Fingerprint Identification
Testimony, 70 Fordham L. Rev. 2819 (2002), <http://ir.lawnet.fordham.edu/flr/vol70/iss6/30> Accessed
10 December 2011.
121
Law Commission, 'The Admissibility of Expert Evidence in Criminal Proceedings in England and
Wales: A New Approach to the Determination of Evidentiary Reliability' LCCP No.190 (2009).
122
Gary Edmond, et al, 'The Law Commission's report on expert evidence in criminal proceedings' [2011]
Crim. L.R.844-862
123
Law Commission No.190: 2.12.
124
Law Commission No. 190: 2.12.
125
Adam Wilson, 'The Law Commission's proposal on expert opinion evidence: an onerous demand upon
judges' (2010) 1 Web JCLI <http://webjcli.ncl.ac.uk/2010/issue1/wilson1.html> Accessed 29 November
2011.
126
Ibid.
120
19
outside a judge or jury’s experience or knowledge, and which would give them help
they need in arriving at their conclusions; secondly the witnesses must be qualified;
thirdly the evidence is not made inadmissible as a result of clause 3 (Impartiality). 127
The Commission also proposed a new statutory provision that expert opinion evidence
is admissible only if the court is satisfied that it is sufficiently reliable to be admitted. 128
The distinctive feature of this proposal lay in the Commission's clear articulation of the
methodology required to establish reliability.129
The Commission concluded that the present law common law approach to the
admissibility of expert evidence in criminal proceedings in England and Wales is
unsatisfactory and should be replaced with a new statutory test.130 The Commission
suggested that a Daubert-style reliability test in tandem with appropriate training for the
judiciary and practitioners, offers the best mechanism for excluding unreliable expert
evidence.131 The Commission set out four proposals aimed at ensuring expert evidence
will be submitted only if it is sufficiently reliable and ultimately acted out upon by the
jury.132 The key proposal was that there should be an explicit “gate-keeping” role for the
trial judge with a clearly-defined test for determining whether proffered expert evidence
is sufficiently reliable to be admitted.133 The Commission also proposed that there
should exist the onus of persuasion - if a party proposes to rely on expert evidence, any
party against whom the evidence would be adduced should be entitled to raise the
‘Expert Evidence Reliability to be tested by judges – Law Commission Report’ (22 March 2011) <
http://obiterj.blogspot.com/2011/03/expert-evidence-to-be-tested-by-judges.html> Accessed 10 February
2012.
128
Law Commission No. 190: 2.23.
129
Adam Wilson, 'The Law Commission's proposal on expert opinion evidence: an onerous demand upon
judges' (2010) 1 Web JCLI <http://webjcli.ncl.ac.uk/2010/issue1/wilson1.html> Accessed 29 November
2011.
130
Law Commission No. 190: 5.1.
131
Law Commission No. 190: 5.1.
132
Law Commission No. 190: 6.1.
133
Law Commission No. 190: 6.4.
127
20
question of its evidentiary reliability.134 In addition the Committee also noted that the
judge should be permitted to call upon an independent assessor to provide him or her
with assistance and guidance in cases where the evidence of field is particularly
difficult.135 The Commission also noted that judges (and criminal practitioners) should
receive practical training on the methodology of science, the standards for determining
the statistical significance of research findings and how to determine the reliability of
experience-based expertise.136
The Law Commission's proposal on expert opinion evidence has since been criticised,
with one article claiming that whilst the criteria set out in the paper are clearly
articulated applying them to forensic disciplines is 'fraught with difficulty.'137 The article
also suggests that the proposal places an onerous demand upon judges, who have the
difficulty of interpreting the criteria.138 If interpreted too strictly it could lead to the
exclusion of forensic testimony becoming widespread.139 On the other hand, if
interpreted too liberally, the criteria will not provide adequate safeguards against
admission of unfounded evidence.140The article rejects the criteria based approach
towards admission, suggesting instead, that forensic science should be evaluated by
carefully constituted working parties outside the courtroom.
134
Law Commission No. 190: 6.53.
Law Commission No. 190: 6.65.
136
Law Commission No. 190: 6.72.
137
Adam Wilson, 'The Law Commission's proposal on expert opinion evidence: an onerous demand upon
judges' (2010) 1 Web JCLI <http://webjcli.ncl.ac.uk/2010/issue1/wilson1.html> Accessed 18 December
2011.
138
Ibid.
139
Adam Wilson, 'The Law Commission's proposal on expert opinion evidence: an onerous demand upon
judges' (2010) 1 Web JCLI <http://webjcli.ncl.ac.uk/2010/issue1/wilson1.html> Accessed 19 December
2011.
140
Ibid.
135
21
CONCLUSION
DNA profiling technology has improved greatly since the days when a visible blood
drop or reasonable sized stain was required to obtain a profile.141 New techniques such
as LCN now allow for the analysis of more difficult and challenging samples which
may contain DNA from only a few cells.142 These new techniques are undoubtedly of
tremendous value in criminal investigations, however, failure to interpret DNA profiles
using standard scientific principles will almost certainly result in significant damage,
although unintentional, that could threaten it’s more restricted but beneficial use.143 The
sensitive nature of the LCN technique is accompanied by a number of risks which can
lead to the results failing to be reproducible or accurate. If results cannot be reproduced
reliably or it becomes impossible to scientifically determine the source of the DNA then
how can the results of this technique be reliable?
The risks of the LCN technique also mean that there are a number of difficulties
associated with the interpretation of the results even if a DNA profile is accurately
yielded.144 The consequences of amplifying LCN DNA may lead to complex or
incomplete profiles which coupled with inaccurate interpretation could then lead to
wrongful convictions. Despite the inherent dangers of such a technique reviews have
concluded that there is no reason to believe there is any “inherent unreliability” in the
LCN analysis if it is carried out in accordance with prescribed processes and if the
Allan Jamieson, ‘Mixed Results’, The Guardian (28 February 2008). Available from
<http://www.guardian.co.uk/commentisfree/2008/feb/28/ukcrime.forensicscience> Accessed 08 January
2012.
142
Coast, G.& Genetics, I., 2009. Extracting evidence from forensic DNA analyses : future molecular
biology directions. ‘Review Literature and Arts of the Americas’, 46(iii), p.339-40, 342-50.
143
Allan Jamieson, ‘Mixed Results’, The Guardian (28 February 2008).
144
Michael Naughton et al, ‘The need for caution in the use of DNA evidence to avoid convicting the
innocent’ E. & P. 2011, 15(3), 245-257.
141
22
results are properly interpreted.145 The onus is then on the judge to scrupulously protect
the jury from unreliable scientific evidence.146
The following chapters intend to look at the dangers which exist if the results of
forensic DNA analysis are incorrectly interpreted and just how essential it is to
correctly analyse the reliability, validity and accuracy of the results to prevent future
miscarriages of justice. In doing so, it will look at the difficulties facing the forensic
science community who must scientifically interpret the results and the jury who must
reach a verdict based on the results.
CPS Press Release ‘Review of the use of Low Copy NumberDNA analysis in current cases: CPS
Statement’, 14 January 2008, Available <http://www.cps.gov.uk/news/press_releases/101_08/> Accessed
02 December 2011.
146
Robert D. Myers, et al., “Complex Scientific Evidence and the Jury” (American Judicature Society,
November-December 1999) Vol 83(3).
145
23
CHAPTER 2: THE SCIENTIFIC INTERPRETATION OF DNA EVIDENCE
Scientific evidence can be problematic for courts: the subject matter is often complex,
the experts can be biased and the judge and juries may be unsure of how to interpret the
evidence once it has been presented in court.147 At an even more fundamental level,
miscarriage of justice will arise if the science underlying the expert evidence presented
in Court is not sound. Interpretation of forensic evidence often has to be performed
within a framework appropriate for both scientific analysis and presentation in court.148
Forensic DNA analysts often testify to their findings using statistical probabilities rather
than statements of certainty which can turn out to be arbitrary and unsupported.149 The
field of DNA analysis still requires a great deal of analysis as the apparent certainty of
this powerful investigative tool can be deceptive and this can lead to it being misused
and misapplied.150 There are many ways to introduce results to the jury and it is
important for DNA results and results from a number of other disciplines to be
accurately presented to the jury. One discipline which will be discussed is the field of
shoe mark analysis.
DIFFERENT MODES OF PRESENTING RESULTS
In the case of R v T, shoe marks were recovered from the crime scene by the forensic
footwear expert, Mr Ryder, which he compared to shoes which had been recovered
from the defendant’s property.151 Mr Ryder concluded that “… it is somewhat unlikely
John Danaher, ‘Blind expertise and the problem of scientific evidence’, The International Journal of
Evidence and Proof, E. & P. 2011, 15(3), at 207.
148
Andrei Semikhodskii, ‘Dealing with DNA Evidence: a Legal Guide’ (Routledge-Cavendish; 1 edition
(25 Jan 2007) at 51.
149
Michael J. Saks & Jonathan J. Koehler, The Coming Paradigm Shift in Forensic Identification Science,
309 Science 892, 893 (2005).
150
Ibid.
151
R v T [2010] EWCA 2349.
147
24
that the observed correspondence would have been obtained as a result of mere
coincidence had the recovered footwear not made the mark in question… there is at this
stage a moderate degree of scientific evidence to support the view that the shoes
recovered had made the footwear marks.”152 The question before the court was
therefore whether the Bayesian approach of using likelihood ratios had been applied in
this case, an approach which the court had ‘…robustly rejected for non DNA evidence in
a number of cases’.153 The Court of Appeal allowed T’s appeal against conviction
because it became apparent that ‘the Bayesian approach” of using likelihood ratios’ had
been applied and this ‘had not been explored in the course of the trial.154
Many leading scientists are of the opinion that the likelihood-ratio framework is the
most logically correct framework for the evaluation of forensic science evidence and
should be applied irrespective of the structure of the data extracted from the objects.155
The idea that the likelihood-ratio framework is the most logical approach to evaluating
forensic science evidence dates back to the early 1900s156 and it became standard
practice in forensic DNA comparison in the mid-1990’s.157 It has since been adopted by
the Forensic Science Service (FSS)158 and the Netherlands Forensic Institute.159
Throughout R v T the Court of Appeal heard from a number of expert witnesses,
including the principal scientist at the Forensic Science Service (FSS) responsible for
marks and setting standards, and chair of the European Network of Forensic Science
152
R v T [2010] EWCA Crim 2439, [2011] 1 Cr App R 9 at [24].
Ibid. at [46].
154
Ibid. at [45].
155
Geoffrey S. Morrison, ‘The likelihood-ratio framework and forensic evidence in court: a response to R
v T’, E. & P. 2012, 16(1), at 2.
156
J. G. Darboux, P. E. Appell and J. J. Poincaré, ‘Affaire Dreyfus: Rapport de MM. les Experts
Darboux, Appell, Poincaré’ (1904), available at <http://www.maths.ed.ac.uk/%EBaar/dreyfus.htm>,
accessed 05 January 2011.
157
L. A. Foreman, C. Champod, I. W. Evett, J. A. Lambert and S. Pope, ‘Interpreting DNA Evidence: A
Review’ (2003) 71 International Statistics Journal 473.
158
R. Cook, I. W. Evett, G. Jackson, P. J. Jones and J. A. Lambert, ‘A Hierarchy of Propositions:
Deciding Which Level to Address in Casework’ (1998) 38 Science & Justice 231.
159
C. E. H. Berger, ‘Criminalistiek is terugredeneren’ [Criminalistics is reasoning backwards] (2010)
Nederlands Juristenblad 784.
153
25
Institutes’ expert working group on marks, the principal scientist at the FSS responsible
for Care Assessment and Interpretation and from the UK’s Forensic Science
Regulator.160 The likelihood ratio was strongly recommended by the above experts and
also by a growing number of forensic scientists within the United Kingdom.161
The Forensic Science Regulator has gone on to suggest that it was illogical to say the
Bayesian or likelihood ratio approach could be used in some areas of scientific
evidence, but not in others.162 The Appeal Court adopted a different position stating that
‘we do not agree with the observations of the Regulator that a similar approach is
justified in all areas of expertise’.163 In response to the ruling in R v T, many forensic
scientists have voiced their opinion that the Likelihood-ratio framework remains the
most appropriate framework for the evaluation of forensic science evidence,
164
even
signing a statement to this effect.165
UNIVERSAL STANDARDS AND BEST PRACTICE
In 2009, The National Academy of Science published a report ‘Strengthening Forensic
Science in the United States: A Path Forward’ which outlined the challenges facing the
forensic science community, and made recommendations which aim for universal
standard and best practice.166 In 2005, the Science, State, Justice, Commerce and
Related Agencies Appropriations Act of 2006 came into force.167 Under this Act,
160
R v T [2010] EWCA Crim 2439, [2011] 1 Cr App R 9 at [47].
Geoffrey S. Morrison, ‘The likelihood-ratio framework and forensic evidence in court: a response to R
v T’, E. & P. 2012, 16(1), at 1.
162
R v T [2010] EWCA Crim 2439, [2011] 1 Cr App R 9 at [61].
163
R v T [2010] EWCA Crim 2439, [2011] 1 Cr App R 9 at [76].
164
Geoffrey S. Morrison, ‘The likelihood-ratio framework and forensic evidence in court: a response to R
v T’, E. & P. 2012, 16(1), at 3.
165
I. W. Evett and other signatories, ‘Expressing Evaluative Opinions: A Position Statement’ (2011) 51
Science & Justice 1.
166
Committee on Identifying the Needs of the Forensic Sciences Community, National Research Council,
Strengthening Forensic Science in the United States: A Path Forward, National Academies Press (1 Dec
2009).
167
Science, State, Justice, Commerce, and Related Agencies Appropriations Act, 2006 [H.R.2862.ENR]
161
26
Congress authorised the National Academies of Sciences to conduct a study on forensic
science, stating “While a great deal of analysis exists of the requirements in the
discipline of DNA, there exists little to no analysis of the remaining needs of the
community outside of the area of DNA”168 Although in theory the Committee was not
given the task of specifically studying DNA evidence, the very essence of it is entwined
throughout the report.169 The Committee were instructed to focus ‘outside of the area of
DNA’170 and instead focused their attention on alternative forensic science techniques
such as fingerprint examination. Although DNA may not be at the forefront of the NAS
Report, the role which forensic DNA analysis has played in the history of forensic
science is evident throughout.171 The long anticipated report largely states what
academics and scientists have noted for some time – that the state of the science used in
forensic science and thus in the criminal justice system is extremely poor.172
The overriding message of the NAS Report was that forensic science has failed to meet
the demands of science.173 Essentially, the Committee called for an overhaul of the
practice and procedures of many forensic science disciplines, including fingerprint
analysis, hair and fibre evidence and the identification of shoe prints.174 The NAS
Committee proposed 13 recommendations. One of the main recommendations of the
NAS Report was that Congress establish an independent federal entity, the National
Institute of Forensic Science (NIFS), to oversee and establish standards, research,
forensic practices, education, certification, accreditation and development of
168
Senate Report No. 109‑88, at 46 (2005).
Erin Murphy, ‘What “Strengthening Forensic Science” today means for tomorrow: DNA
exceptionalism and the 2009 NAS Report’, L.P. & R. 2010, 9(1), 7-24 at 7.
170
Senate Report NO.109-088, at 46 (2005).
171
Erin Murphy, ‘What “Strengthening Forensic Science” today means for tomorrow: DNA
exceptionalism and the 2009 NAS Report’, L.P. & R. 2010, 9(1), 7-24 at 1.3.
172
Erin Murphy, ‘What “Strengthening Forensic Science” today means for tomorrow: DNA
exceptionalism and the 2009 NAS Report’, L.P. & R. 2010, 9(1), 7-24 at 7.
173
Jacqueline T. Fish Dr., ‘Crime Scene Investigation’ (Anderson; 2 edition (13 Dec 2010) 13.
174
Ibid.
169
27
technology.175 Other recommendations included establishing standard terminology and
reporting procedures and to conduct research to address issues of accuracy, reliability
and validity.176 Congress has not yet acted upon the recommendations of the NAS
Report, but the findings of the report have echoed throughout the forensic science
community and parts of the legal community.177 Formally, the scientific organisations
have supported the general recommendations of the report whilst maintaining the belief
that future scientific research will validate most of the bases of forensic science
discipline.178 In the aftermath of the NAS report, it is clear that cases that rest wholly or
partly on forensic evidence must be carefully scrutinised.
CONCLUSION
Complex scientific evidence increasingly plays a role in many of today’s court
rooms.179 Testimony from forensic DNA analysts can overwhelm jurors who often have
limited knowledge of the concepts of biology, genetics and technology used to generate
DNA profiles.180 This then raises the question: If jurors do not understand the science
underpinning the evidence, how can they then correctly interpret the evidence once it
has been presented in court? New Zealand scientists John Buckleton and James Curran
have said: “There is a considerable aura to DNA evidence. Because of this aura it is
vital that weak evidence is correctly represented as weak or not represented at all.”181
Where there is uncertainty in the data (e.g. with complex DNA mixtures, partial profiles
175
Ibid.
Jacqueline T. Fish Dr., ‘Crime Scene Investigation’ (Anderson; 2 edition (13 Dec 2010) 13.
177
Donald Shelton, Forensic Science in Court: Challenges in the Twenty First Century (Rowan and
Littlefield Publishers, 2011) 131.
178
Ibid at 132.
179
Stephanie Albertson, The influence of jurors race on perceptions of complex scientific evidence
(University of Delaware, 2009) 1.
180
John M. Butler, Advanced Topics in Forensic DNA Typing: Methodology (Academic Press; 3rd Edition
(27 July 2011) 542.
181
J. Buckleton,J. Curran, A discussion of the merits of random man not excluded and likelihood ratios,
Forensic Sci Int Genet. 2 (2008) 343-8.
176
28
or low level DNA templates) this should be emphasised so that the jurors may
appropriately evaluate the weight that should be given to the evidence which has been
presented.182 It is apparent that there is still a great deal of confusion regarding the
presentation of statistical evidence to juries and in particular the field of DNA still
requires a great deal of analysis.183 The inherent danger of this forensic science
technique arises if the scientific data underlying the DNA results has been inaccurately
presented to the jury. More importantly what influence can these potentially incorrect
perceptions regarding scientific data have on a juror’s decision making ability?
182
John M. Butler, Advanced Topics in Forensic DNA Typing: Methodology (Academic Press; 3rd Edition
(27 July 2011) 542.
183
Science and Technology Committee Publications, Science and Technology: Seventh Report (16 March
2005) <http://www.publications.parliament.uk/pa/cm200405/cmselect/cmsctech/96/9602.htm> Accessed
08 Feb 2012.
29
CHAPTER 3: THE LAY INTERPRETATION OF DNA EVIDENCE
Given the scientific admissibility and reliability of this technique, DNA is frequently
used in Court therefore this thesis would not be complete without discussing the lay
person interpretation of DNA evidence. Over the past 30 to 40 years, jurors have been
criticised for their interpretation of complex scientific evidence.184 Many critics have
questioned whether a jury of inexperienced and untrained people can reach the correct
decision in trials which require comprehension of substantial qualities of complex
scientific evidence.185 The presence of forensic science evidence, particularly DNA
evidence, predicts convictions.186 Furthermore, much of the critical attention is focused
on so called “first generation techniques” – methods such as handwriting analysis,
ballistics and tool or bite mark analysis.187 Forensic DNA analysis is often excluded
from critiques of forensic methods188 as it is assumed to exemplify the kind of scientific
rigor that first generation techniques have not been subjected to. 189 A lay person who is
only slightly acquainted with forensic techniques may suspect that “first generation”
techniques are not as scientific or objective as forensic DNA analysis and this could
prove dangerous when interpreting DNA evidence. The jury’s interpretation of this
complex scientific and technical evidence is key in ensuring justice is done. As the
admissibility of certain DNA profiling techniques has become less controversial, an
Robert D. Myers, et al., ‘Complex Scientific Evidence and the jury’ (1999) Vol 83 (3) American
Judicature Society
<http://www.ornl.gov/sci/techresources/Human_Genome/publicat/judicature/article10.html> Accessed 06
Feb 2012.
185
Ibid.
186
Jane G. Delahunty, ‘DNA, Jury Trials and the White Coat Effect’, available
<http://www.lawlink.nsw.gov.au/lawlink/pdo/ll_pdo.nsf/vwFiles/DNA&JuryTrials.pdf/$file/DNA&JuryT
rials.pdf> Accessed 20 November 2011.
187
Erin Murphy, The New Forensics: Criminal Justice, False Certainty, and the Second Generation of
Scientific Evidence, 95 CAL. L. REV. 721, 754–56 & nn.149–56 (2007) at 726-31.
184
188
189
Erin Murphy, The New Forensics: Criminal Justice, False Certainty, and the Second Generation of
Scientific Evidence, 95 CAL. L. REV. 721, 754–56 & nn.149–56 (2007) at 728-31.
30
important question remains: Are jurors able to understand the complex scientific and
inherently probabilistic testimony that accompanies a DNA match report? 190
SCIENTIFIC EVIDENCE & THE JURY 191
DNA evidence is a crucial predictor of guilty verdicts in jury trials. 192 Juror difficulties
in understanding and applying the scientific and statistical information conveyed by
forensic experts about a DNA match have been documented in a number of studies.193
Post-trial interviews of jurors in six criminal trials revealed that jurors who admitted to
difficulty in understanding DNA expert evidence presented convicted despite the lack of
understanding.194 Jurors often have high expectations of scientific evidence with a
study held in 2008 stating that 46% of jurors “expected to see some kind of scientific
evidence in every criminal case.”195 The research also found that 22% expected to see
DNA evidence in every case.196 One Court described this troubling aspect of scientific
evidence as its ability to assume “a posture of mystic infallibility in the eyes of the
jury.”197 The very fact that the judge has admitted DNA evidence into the courtroom
often leads to juror assumption that the evidence must be reliable and therefore jurors
Jason Schklar, et al., ‘Juror Reactions to DNA Evidence: Errors and Expectancies’ Law and Human
Behavior, Vol. 23, No. 2. (April 1999) P159 -184 at 159
191
It is interesting to note beyond the scope of this thesis that the jury system in Japan was abolished in
1943 and as a result the legal process was strictly for professionals. The jury system was then brought
back in and judges in Japan now assist the jury. It is not a direct copy of the system in the UK but it is
interesting to note a number of similarities and the difference in the success of both.
192
Robert J Goodwin, Criminal and Scientific Evidence Cases, Materials and Problems (Lexis Law Pub
(April 1997) 51.
193
Jane Delahuntly, ‘Improving Jury Understanding and the use of DNA Expert Evidence’ (Criminology
Research Council, July 2009) <http://www.criminologyresearchcouncil.gov.au/reports/05-0708.pdf>
Accessed 01 March 2012.
194
Ibid.
195
Larry J Siegel, Introduction to Criminal Justice (Wadsworth Publishing Co Inc; 12th edition (5 Jan
2009) 475.
196
Ibid.
197
United States v Addison 498 F.2d 741, 744 (D.C Circ 1974)
190
31
tend to rely on the results without thoroughly questioning it and this is where the danger
lies.198
‘WHITE COAT SYNDROME’
A juror can appear to be susceptible to ‘White Coat Syndrome’ if when faced with DNA
evidence in a criminal trial, they are inclined to believe ‘science does not lie’.199 This
belief generates confidence and leads to DNA evidence being regarded as infallible.200
According to new reports from The Australian Institute of Criminology Research jurors
are often not confident enough in their knowledge of DNA evidence which may often
go against the accused when a guilty verdict is returned.201 Professor Jane-Goodman
Delahunty says “They tend to regard it as infallible and so once it comes in, the very
fact that the judge has admitted the evidence is often construed as an indication that it
must be reliable, and therefore rely on it without questioning it very thoroughly.”202
Without questioning the science underpinning the evidence, it is difficult to correctly
interpret the evidence taking into consideration the fragilities of the technique.
Professor Delahuntly conducted a study of around 400 people to find out what their
response would be to DNA evidence in mock murder trials.203 The study found that
people with a low understanding of DNA convicted at a rate of 75%, while those with a
better knowledge had 42% conviction rate.204 She noted; "The conviction rate is far
Lindy Kerin ‘Jurors overwhelmed by DNA evidence: Study’ (The World Today, March 29 2010) <
<http://www.abc.net.au/worldtoday/content/2010/s2858961.htm> Accessed 18 February 2012.
199
Benjamin R. Newell, et al., Straight Choices: The Psychology of Decision Making (Psychology Press;
1 edition (14 Jun 2007) 7.
200
Ibid.
201
Ananya Mandal, ‘DNA evidence often overwhelms jurors to wrongly says research’ (News Medical,
29 March 2010) <http://www.news-medical.net/news/20100329/DNA-evidence-often-overwhelmsjurors-to-convict-wrongly-says-research.aspx> Accessed 23 Feb 2012.
202
Ibid.
203
Lindy Kerin, ‘Jurors overwhelmed by DNA evidence: Study’ (ABC News, March 2010)
<http://www.abc.net.au/worldtoday/content/2010/s2858961.htm> Accessed 23 Feb 2012.
204
Ibid.
198
32
higher than the scholars think it ought to be, if you look at the weight that the evidence
might warrant."205
It has been questioned whether jury innovation trials could improve juror understanding
of DNA evidence. The National Institute of Justice conducted a study on the impact of
jury trial innovations upon mock jurors.206 Although this particular study was focused
on mitochondrial DNA this would have broader application to nuclear DNA. The
research showed that jurors used three of the innovations the most—the multipurpose
notebook, note taking, and the mtDNA checklist.207 The multipurpose notebook was the
most popular innovation: 92% of the jurors said that the notebooks—in particular, the
expert’s slides—helped them to remember and understand the case.208 The second most
used innovation was juror note taking with 88% of jurors who took notes. Two-thirds
said their notes helped them remember the evidence.209 The third most used innovation
was the mtDNA checklist: 85% of jurors allowed to use the checklist said they reviewed
it during deliberations. Most found that the checklist increased their understanding and
recall of the evidence.210 The least used innovation was jury questioning: only 22% of
the jurors allowed to ask questions actually did.211 Based on the study, researchers
believe that the use of certain jury innovations has the potential to improve jurors’
comprehension of mtDNA and other scientific evidence.
212
Methods that provided
direct guidance or additional expert information—such as the mtDNA checklist and the
Ananya Mandal, ‘DNA evidence often overwhelms jurors to wrongly says research’ (News Medical,
29 March 2010) <http://www.news-medical.net/news/20100329/DNA-evidence-often-overwhelmsjurors-to-convict-wrongly-says-research.aspx> Accessed 23 Feb 2012.
206
Michael Dann, et al., ‘Can Jury Trial Innovations Improve Juror Understanding of DNA Evidence?’
(National Institute of Justice Journal, Issue no 255) 4.
207
Ibid.
208
Ibid
209
Ibid.
210
Ibid at 5
211
Ibid at 5
212
Ibid at 5.
205
33
juror notebook—best improved juror understanding.213 This suggests that other jury
innovations that provide a better understanding of expert evidence such as juror tutorials
in complex subjects and court-appointed experts to discuss the parties’ often conflicting
scientific evidence are ripe for evaluation.214 The results of the study showed that most
juries are capable of comprehending and using different forms of DNA evidence at trial.
Nonetheless, researchers acknowledged that some jurors are likely to have trouble with
complex DNA evidence.215
THE ‘CSI EFFECT’
A more modern interpretation of white coat syndrome is ‘the CSI effect’ which has been
described as “… the perceptions of the near-infallibility of forensic science in response
to the TV show”.216 There are a number of differences between the fact and fiction of
forensic science evidence and this has been seen to have a variety of effects on
American Society.217 One forensic scientist, Thomas Mauriello, estimates that only 40%
of the so called “science” on CSI does not exist and the rest is an unrealistic portrayal of
what actually happens in crime labs.218 There are a number of theories surrounding the
effect of CSI style programmes however; the one that is heard most often is that CSI has
raised the expectations of the public as to what type of evidence may be offered at trial
Michael Dann, et al., ‘Can Jury Trial Innovations Improve Juror Understanding of DNA Evidence?’
(National Institute of Justice Journal, Issue no 255) 4.
214
Ibid.
215
Ibid.
216
J. Heinrick, ‘Everyone’s an Expert: The CSI Effect’s Negative Impact on Juries’ (2006)
<http://www.cspo.org/documents/csieffectheinrick.pdf> Accessed 15 November 2011.
217
Kimberlianne Podlas, “The CSI Effect”: Exposing the Media Myth, 16 Fordham Intell.. Prop. Media &
Entertainment L.J. 429 (2006).
218
Simon Cole & Rachel Dioso, Law and the Lab: Do TV Shows Really Affect How Juries Vote? Let’s
Look at the Evidence, WALL ST. J., May 13, 2005, at W13.
213
34
to such a level that jurors are disappointed by the real evidence presented.219 As a result,
jurors are more likely to acquit an accused on the basis that there is not enough forensic
science provided in court to persuade them of guilt.220 Most recently, the “Tech-Effect”
theory has replaced the “CSI-Effect” theory as a means to explain the potential impact
of technology on jurors.221 This theory argues that crime dramas do not influence jurors;
rather, jurors have heightened expectations for technical and scientific evidence simply
because technology is so advanced in today’s society.222
CONCLUSION
It is difficult for jurors to comprehend the complex scientific and inherently
probabilistic testimony accompanying a DNA match report.223 The perception that DNA
is almost infallible and conclusive in all respects has a significant impact on a juror’s
ability to correctly interpret the results of forensic DNA analysis. Phenomena’s such as
the ‘White Coat Syndrome’ and the ‘CSI Effect’ have been found to have a significant
effect on whether a jury will choose to convict or not. Jury innovation trials appear to
suggest that improving the clarity of the evidence and allowing aids can improve juror
understanding with regards to complex scientific evidence.224 It would appear that the
natural progression to improve juror understanding should come in the form of jury
innovation trials which allow for a better understanding of expert evidence such as juror
tutorials in complex subjects and court-appointed experts to discuss the parties’ often
219
N.J. Schweitzer and Michael J. Saks, The CSI Effect: Popular Fiction About Forensic Science Affects
the Public’s Expectations About Real Forensic Science, 47 Jurimetrics J. 357–364 (2007).
220
N.J. Schweitzer and Michael J. Saks, The CSI Effect: Popular Fiction About Forensic Science Affects
the Public’s Expectations About Real Forensic Science, 47 Jurimetrics J. 357–364 (2007).
221
Gary Alan Davis et al., ‘The New Tech Effect: Analysing Juror Credibility in Cases Involving Digital
Evidence’ (2011) <http://proc.conisar.org/2011/pdf/1831.pdf> at 1. Accessed 16 Feb 2012.
222
Ibid
223
Jason Schklar, et al., ‘Juror Reactions to DNA Evidence: Errors and Expectancies’ Law and Human
Behavior, Vol. 23, No. 2. (April 1999) P159 -184 at 159
224
G.T Munsterman, Jury Trial Innovations (National Center for State Courts (Jan 1997) 2.
35
conflicting scientific evidence.225 There should exist a greater awareness of forensic
DNA analysis as suggested in the Caddy Review when it stated that the results of LCN
DNA should be “reported to the jury with caveats” and that the results of LCN must be
interpreted cautiously and all factors regarding the extreme sensitivity of the technique
to be taken into consideration by the jury.
225
Ibid.
36
CHAPTER 4: CONCLUSIONS & RECOMMENDATIONS
DNA analysis is an extremely powerful scientific tool which has proved to be
invaluable to both the forensic science and legal communities.226 Forensic DNA
analysis for identification purposes affords several advantages to law enforcement and
legal systems227 which make possible both apprehension of criminals and exoneration of
those wrongly convicted.228 There are many advantages of this technique: it can be said
to be a more reliable form of evidence than eyewitness testimony which was previously
used and it provides a scientific basis which allows for a physical link to be made
between a criminal and a crime scene in order to secure a conviction. The availability of
such a technique has also allowed for the introduction of Innocence Projects which have
used forensic DNA analysis to help exonerate those who have been wrongly convicted.
The magnitude of Innocence Projects worldwide success is a reminder of the significant
benefits which DNA profiling has brought to the criminal justice system, however, the
expansion of new techniques has increased the sensitivity of forensic DNA analysis and
as a result the dangers of incorrect interpretation are now more significant than ever
before.
The process of forensic DNA analysis is very important and if the results are not
reliable, accurate, valid and reproducible then how is it then possible to interpret the
results correctly? The validity of one such new technique, LCN DNA, has been a
controversial matter.229 There are a number of risks which accompany the LCN
technique and it is clear that special consideration must be given when interpreting LCN
226
Shelton, Donald. Forensic science in court challenges in the twenty-first century, (Lanham, Md:
Rowman & Littlefield Publishers, 2011) 28.
227
U.S. Congress Office of Technology Assessment, Genetic Witness: Forensic uses of DNA tests, OTABA-438 (Washington, DC: U.S. Government Printing Office, July 1990) 17.
228
David R. Keller et al., Ethics in Action: A Case Based Approach (Wiley-Blackwell, 19 Dec 2008) 454.
229
Law Commission, ‘Low Copy Number (LCN) DNA revisited’ (CLW 2010, Issue No. 23 at 1)
Available
<http://www.gcnchambers.co.uk/gcn/areas_of_specialisation/areas/criminal_defence/criminal_law_updat
es/criminal_law_update_20_01_10> Accessed 10.12.2011.
37
DNA results. A number of factors such as contamination and stochastic effects make
the interpretation of LCN DNA results very difficult. In the case of Hoey, Weir J
emphasised the cardinal principle of criminal law; “Justice ‘according to law’ demands
proper evidence… “evidence which is so convincing in truth and manifestly reliable
that it reaches the standard of proof beyond reasonable doubt.”230 The evidence in
Hoey, which based primarily on LCN DNA evidence, failed to meet such an immutable
standard. If the dangers of LCN DNA are such that it becomes impossible to tell where
such a minute sample came from then how can it be deemed a reliable and valid
scientific technique?
The judgement in Hoey led to a review of the LCN technique and a review by the
Crown Prosecution concluded that LCN DNA analysis should remain as “potentially
admissible evidence.”231 It went on to state that at that time there was no reason to
believe to that there is any “inherent unreliability” in the LCN process provided that it
is carried out according to the prescribed processed and that the results are properly
interpreted. However, the nature of LCN DNA samples make reproducibility a
significant problem for obtaining consistent profiles – if the results are inconsistent how
then is it possible to give a reasoned interpretation of them? The Caddy Review also
concluded that the LCN technique is sound again emphasising that all the appropriate
conditions are met. The Caddy Review also empahsised that the LCN DNA profiles
should be “reported to the jury with caveats.” It is clear that in order to be accurate, the
results of LCN must be interpreted cautiously and all factors given the extreme
sensitivity must be taken into consideration. Despite both reviews giving LCN a clean
bill of health, there still exists a great deal of scientific ambiguity with regards to the
230
R v Hoey [2007] NICC 49 at 65.
CPS Press Release ‘Review of the use of Low Copy Number DNA analysis in current cases: CPS
Statement’, 14 January 2008, Available <http://www.cps.gov.uk/news/press_releases/101_08/> Accessed
02 December 2011.
231
38
general uses of the technique. In the mind of a juror, however, there does not exist a
great deal of difference between standard DNA analysis and the more sensitive
techniques such as LCN – DNA continues to predict convictions and this is where the
problem lies.
The Law Commission Consultation Paper 190, ‘The Admissibility of Expert Evidence in
Criminal Proceedings in England and Wales: A New Approach to the Determination of
Evidentiary Reliability’232 reiterated that there is a growing dissatisfaction with the law
relating to the admission of expert evidence. The Paper suggested that there should be
an explicit “gate-keeping” role and that the onus is on judges to protect the jury from
unreliable scientific evidence. The Law Commission’s proposal on expert opinion
evidence has since been criticised in that it places an onerous demand upon judges, who
have the difficulty of interpreting the criteria. If interpreted too strictly, this could lead
to the exclusion of forensic testimony becoming widespread. On the other hand, if
interpreted too liberally, the criteria will not provide adequate safeguards against
admission of unfounded evidence. A major issue with this proposal is that the scientific
nature of forensic DNA analysis has the potential to confuse not only the jury but also
the trial judge which could lead to the judge admitting scientific evidence which is
unfounded.
It is essential for the forensic science community to correctly analyse and interpret the
results and to present truthfully to the jury in a language which they understand. There
are many difficulties which face the forensic science community when it comes to the
interpretation of DNA results. It is essential that the science underlying the expert
evidence is sound. In 2009, The National Academy of Science published a report
232
Law Commission, 'The Admissibility of Expert Evidence in Criminal Proceedings in England and
Wales: A New Approach to the Determination of Evidentiary Reliability' LCCP No.190 (2009).
39
‘Strengthening Forensic Science in the United States: A Path Forward’233 which
outlined the challenges facing the forensic science community. Although this report
placed DNA evidence on a pedestal, it identified that the state science in forensic
science and the criminal justice system is very poor. If the science underlying the results
is not sound then how can it be viewed as reliable?
Complex scientific evidence can be difficult for jurors to comprehend which makes
their task of interpretation more difficult. If jurors do not understand the science
underpinning the results, how can they correctly interpret the evidence once it has been
presented in court? The jurors have the final say in the interpretation of the results of
DNA evidence and accurate interpretation of this complex scientific and technical
evidence by the jury is key in ensuring justice is done. A number of studies have
documented that jurors have difficulty in understanding and applying the scientific and
statistical information and jurors have admitted to convicting despite the lack of
understanding of the evidence. It has been questioned whether jury innovation trials
could improve juror understanding of DNA evidence and results show that innovation
trials do have the potential to improve jurors comprehension of complex scientific
evidence which would allow jurors to take more consideration before placing too heavy
a reliance on the results.
Although the dangers of forensic DNA analysis are routinely recognised, little seems to
have been done to improve the reliability of the technique. To ensure justice is done, it
is important for correct interpretation at every stage of the process – from the forensic
scientists who analyse it, to the judges who make a decision on the admissibility of it, to
finally the jurors who make a final decision based on the results. At present, it is clear
that there exists too heavy or simplistic reliance on the results. Forensic DNA analysis is
233
Committee on Identifying the Needs of the Forensic Sciences Community, National Research Council,
Strengthening Forensic Science in the United States: A Path Forward, National Academies Press (1 Dec
2009).
40
a technique which, although widely accepted by the scientific and legal communities,
still requires a great deal of analysis.
There are a number of recommendations which could improve the reliability of DNA
evidence. Firstly, more research into LCN and its scientific reliability, reproducibility
and validity could improve the use of the technique and ensure that its limitations are
clear. Secondly, more research into juries could be conducted to see how they respond
to current DNA evidence and how presentation of the evidence can be improved to
increase comprehension and to reduce the CSI effect. Jury innovation trials have already
been seen to improve juror understanding of this complex scientific evidence. More
public education on the topic could also work to improve awareness of the limitations of
scientific evidence, especially DNA evidence. Thirdly, more training for lawyers and
the judiciary to ensure all scientific evidence is properly scrutinised in court, in line with
the Daubert-style gate-keeping role and the recommendations of the Law Commission.
The above recommendations, if implemented correctly, have the potential to improve
the reliability of DNA evidence and to prevent future miscarriages of justice.
41
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