Opening the Scientific Expert’s Black Box
| Author | Gillian Tully,Emma Piasecki,Sophie Carr,Tim J Wilson |
| DOI | 10.1177/0022018316669220 |
| Published date | 01 October 2016 |
| Date | 01 October 2016 |
| Subject Matter | Articles |
The Journal of Criminal Law
2016, Vol. 80(5) 364–386
Opening the Scientific Expert’s
ª The Author(s) 2016
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DOI: 10.1177/0022018316669220
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in Criminal Evidence
Sophie Carr
Northumbria University, Newcastle, UK
Emma Piasecki
Northumbria University, Newcastle, UK
Gillian Tully
Forensic Science Regulator, Birmingham, UK
Tim J Wilson
Northumbria University, Newcastle, UK
Abstract
The work of forensic scientists, by providing specialist assistance beyond the normal experi-
ence or knowledge of the factfinders, can be elusive to the law’s traditional probative safe-
guards. These safeguards, in any case, only apply to the small proportion of such evidence
actually tested in court. The specialist nature of the scientific work and the knowledge and
understanding needed by users with a non-scientific background makes trust in forensic sci-
ence problematic if conceptualised in binary terms. A systematic review of the development of
the quality controls for the production and use of expert scientific evidence demonstrates that
critical trust, as an organising principle, does offer a continuum (ranging from scepticism to
acceptance) for assessing the reliability and use of forensic science evidence. Despite pro-
gressive reform in forensic science, significant risks remain. These risks are both (i) scientific,
including the fragmentation of scientific interpretation and the assurance that all providers
and/or processes can meet the necessary standards, and (ii) professional, ranging from the
timely provision of information to the ability of counsel to critically test the evidence in a
manner intelligible to the factfinders.
Keywords
Forensic science, expert evidence, critical trust, standard, reliability
Corresponding author:
Emma Piasecki, Northumbria University, Newcastle City Campus, Northumbria School of Law, Newcastle upon Tyne NE1 8ST, UK.
E-mail: emma.piasecki@northumbria.ac.uk
Carr et al.
365
Introduction
The Chief Scientific Adviser’s 2015 Annual Report (hereinafter ‘Walport’) examines the forensic
sciences unconventionally.1 Compared with the courtroom focus in the major surveys of the state of
forensic science, such as Pyrek and the 2010 National Research Council Report, Walport reminds a
forensic community, whose contemporary history and achievements are conceptualised around inves-
tigative (sometimes ‘intelligence’) and probative purposes, that the science they practise or use also
has broader societal and economic purposes. In particular, Walport is concerned with how forensic
science is also engaged in ‘establishing provenance and authenticity and giving assurance in areas
such as environmental protection, food and drink, pharmaceuticals and consumer products’.2 The
results of such scientific work, for example in dealing with food crime, may be used in criminal
proceedings (mainly in magistrates’ courts) to deal with serious individual and societal harm and risks,
although it will be rarely prosecuted by the Crown Prosecution Service (CPS) or included in police
crime data.3,4 This separation of responsibility, however, potentially increases the spread of risks
associated with forensic science, unless, at the intersection of these usually separate streams of
prosecutions, members of the legal profession (prosecutors, defenders and, should the case be dealt
with by a district judge, the factfinder), have sufficient knowledge and understanding of the scientific
issues in the evidence. Hence, there is a need for two qualifications. First, even in the absence of a CPS
review framework, such broader applications of science must still be subject to (and be able to
demonstrate that they satisfy) the epistemological and procedural requirements of criminal justice.
Secondly, the clients responsible for commissioning the original scientific work, such as local author-
ities and the Food Standards Agency, must ensure that their requirements and critical review are
aligned to the legal principles—and professional practices—of expert evidence provision developed
in the more traditionally police-investigated and CPS-prosecuted cases. This is necessary to ensure
that the recent progress, with assuring the probative reliability of expert evidence, is universally
applied in all aspects of scientific analysis that is instructed for a forensic purpose (in the context
of science pertaining to legal proceedings) where the burden of proof is that of beyond reasonable
doubt. The key issue, irrespective of the prosecutor, can then be seen to be the trustworthiness of the
individuals and the organisations involved and the methods they used in the production of such
evidence and its presentation to the factfinders.
Culturally and epistemologically, a great deal of public trust and deference has been invested in what
are widely presented as English criminal law’s defining characteristics—an adversarial hearing in which
the prosecution and defence advance cohesive alternative versions of the events, drawing upon evidence,
including scientific expert evidence, presented in examination and tested in cross-examination to the
1. M. Walport, Annual Report of the Government Chief Scientific Adviser 2015: Forensic Science and Beyond: Authenticity,
Provenance and Assurance, vol. 1 (Government Office for Science: London, 2015). Available at: www.gov.uk/government/
uploads/system/uploads/attachment_data/file/506461/gs-15-37a-forensic-science-beyond-report.pdf (accessed 14 July 2016).
2. Ibid. at 6.
3. For a recent high-profile manslaughter conviction—the death of Mr Paul Wilson due to eating peanuts to which he was allergic
disguised in a curry—the events surrounding this death were investigated jointly by the police and trading standards officers:
Press Association, ‘Restaurant Owner Jailed for Six Years over Death of Peanut Allergy Customer’ (2016) Guardian 24 May.
Available at: www.theguardian.com/society/2016/may/23/restaurant-owner-mohammed-zaman-guilty-of-manslaughter-of-
peanut-allergy-customer (accessed 18 July 2016). Non-CPS prosecutions appear to be running at about 600 a year, see Food
Standards Agency, ‘Food Law Prosecutions Database Published’ (3 November 2015). Available at: www.food.gov.uk/news-
updates/news/2015/14644/food-standards-agency-publishes-food-law-prosecutions-database (accessed 18 July 2016).
4. Most food crime prosecutions in England and Wales are initiated by local authorities. Possibly for this reason they receive less
public attention. Walport itself contributes to conceptual confusion by labelling the section dealing with providence and
authenticity, etc. as ‘Forensic science beyond the court’. See M. Peplow (ed.), Annual Report of the Government Chief Scientific
Adviser 2015: Forensic Science and Beyond: Authenticity, Provenance and Assurance: Evidence and Case Studies 107–57.
Available
at:
www.gov.uk/government/uploads/system/uploads/attachment_data/file/506462/gs-15-37b-forensic-science-
beyond-evidence.pdf (accessed 14 July 2016).
366
The Journal of Criminal Law 80(5)
jury—as a ‘talismanic’ process for trying the most serious criminal cases.5 Even for CPS-prosecuted
crime, however, most cases never reach the Crown Court and, when they do, only a minority are tried
before a jury. Of the persons dealt with by the criminal justice system, some 5 per cent are committed to
the Crown Court for trial and only approximately 0.6 per cent (11 per cent of individuals committed to
the Crown Court) contest the charges.6 Similarly, within magistrates’ courts only about a third of charges
are contested.7
With the exception of electronic crime, the proportion of investigated crime that utilises forensic
science is a relatively small fraction of all crime, and this work, based on the natural sciences (for
example, forensic DNA) or the analysis of physical material (for example, paint analysis), is of greatest
value in a certain classification range of crime types, i.e. those involving some form of physical contact.
This general conclusion holds good even when reliance is placed on the now very dated Runciman Royal
Commission’s 1993 estimate that a third of contested trials involve scientific evidence. The two-way
adversarial argument before a jury, therefore, can expose only a very limited proportion of forensic
science work, excluding electronic forms of crime, in the criminal justice system to any kind of
scrutiny.8 This highlights the need for other methods of inquiry or scrutiny, at various risk points of
the criminal justice system outside court proceedings, where pivotal decision points exist with regard to
the probative value of forensic expert opinion, thereby ensuring that public trust is justified. To this end,
we have taken the concept of critical trust as advocated by Walport as a key element in any framework
for risk management, to analyse specifically whether or not sufficient safeguards are in place to justify
the deference given to the application of forensic science and, more broadly, the practices and processes
within the criminal justice system.
Walport commended the concept of critical trust in both his 2014 and 2015 annual reports:
Most of us have neither the time nor the expertise to examine every decision or explore all the evidence. We
rely on judgements about the values and behaviours of those in charge. For the individual, ‘critical trust’ may
be the best frame of mind: neither outright scepticism nor uncritical acceptance.9
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