FORENSIC SCIENCE EVIDENCE AND THE LIMITS OF CROSS-EXAMINATION.

• Date: 01 April 2019
• Author: Edmond, Gary

Contents I Introduction A A Case Study and a Few Caveats II Adversarial Trials, Trial Safeguards and Cross-Examination III A Brief Overview of Latent Fingerprint Jurisprudence in Australia IV Introducing JP V Comparing Expert Testimony with Scientific Knowledge A Introduction to ACE-V B Scientific Method? ACE-V, Standards and Subjectivity 1 Authoritative Scientific Findings and Recommendations 2 Responses to the Cross-Examination in JP C Error and Error Rates 1 Authoritative Scientific Findings and Recommendations 2 Responses to the Cross-Examination in JP D Expression: The Meaning of Match Decisions 1 Authoritative Scientific Findings and Recommendations 2 Responses to the Cross-Examination in JP E Bias, Blinding and Non-Blind Verification 1 Authoritative Scientific Findings and Recommendations 2 Responses to the Cross-Examination in JP F Uniqueness 1 Authoritative Scientific Findings and Recommendations 2 Responses to the Cross-Examination in JP G Training, Continuing Education and Familiarity with Pertinent Scientific Research H The Code of Conduct for Expert Witnesses VI Injudicious Credulity: Legal Evaluation of the Latent Fingerprint 'Evidence' VII Discussion: Error and Legal Ignorance A Expecting the Defence to Identify an Actual Error B Ignoring Knowledge VIII Conclusion I INTRODUCTION

[Cross-examination] is beyond any doubt the greatest legal engine ever invented for the discovery of truth. ... [C]ross-examination, not trial by jury, is the great and permanent contribution of the Anglo-American system of law to improved methods of trial procedure. (1) The adversarial trial process is predicated on the efficacy of cross-examination as an 'engine ... for the discovery of truth'. (2) As Wigmore's quote demonstrates, common law scholars have not been shy about ascribing near mystical powers to skilled cross-examination. This article offers a critical reassessment of the trust that orthodox legal doctrine places in the efficacy of cross-examination, specifically in respect of the challenge of identifying and conveying significant problems with forensic science evidence.

In this article, we build on a growing body of scholarship about these problems, including work that documents the failure of legal processes to identify and counter problems with forensic science evidence. In order to illustrate how cross-examination fails to serve its supposed function as an engine for truth, we present a case study: an unsuccessful challenge to the probative value of latent fingerprint evidence. Our study--based on R v JP (3) and (on appeal) JP v Director of Public Prosecutions (NSW) (4) (collectively 'JP')--suggests that cross-examination is not necessarily effective in influencing fact-finders' assessment of the probative value of expert opinions in criminal proceedings. This is so even when, as in this instance, the cross-examination was well-prepared and directed at forensic science testimony that was exaggerated, misleading and failed to incorporate or address relevant scientific knowledge.

The frailties of cross-examination are not, of course, the only structural impediment to accurate fact determination in cases involving forensic science evidence. The ensuing analysis should be read in the context of weak admissibility standards, limited resourcing (especially for the defence), and increasing reliance on so-called trial safeguards such as rebuttal witnesses, admissibility compromises and judicial instructions. We have previously written, separately and collectively, about each of these problems. (5) However, our analysis of the failures of cross-examination is important because it is inconsistent with orthodox legal commitment to the efficacy of cross-examination as an 'engine' with the tendency to make criminal proceedings fair and the state, through its expert witnesses, accountable.

This article explores the difficulties encountered by defendants, and their (usually publicly-funded) lawyers, when attempting to demonstrate nontrivial limitations with forensic science evidence adduced by the state. (6) Rather than rely exclusively on the interactions--the questions and particularly the responses--from the trial (and the voir dire), our analysis juxtaposes responses from the transcript with scientific research and authoritative scientific pronouncements. This method allows us to contrast the testimony from the proceedings with what is known about forensic science evidence in academic, scientific and policy realms beyond the courtroom. We consider these academic, scientific and policy perspectives to be the benchmark of institutional knowledge regarding the forensic sciences. Our approach enables the reader to observe conspicuous differences between the trial evidence and this benchmark, as well as the inability of participants, including the 'expert' witness and judicial officers, to appreciate their significance. (7)

The issues canvassed in this article are particularly important for non-DNA feature comparison procedures, such as latent fingerprints, ballistics, tool marks, handwriting and documents, shoe, tyre, paint, hair and fibre, soil, image, gait and voice comparison evidence. Mainstream scientific knowledge is rarely presented to the trier of fact in criminal prosecutions where evidence derived from these procedures is adduced and relied upon by the state. (8) On the relatively rare occasions when methodological and other epistemologically destabilising issues are raised, our experience--which resonates with the course of events in the case study--suggests that it is unlikely that those issues will be understood or taken seriously. (9) Further, judicial intervention at trial--most likely to manifest through the provision of directions and instructions on evidence and the burden of proof--is unlikely to assist with problems. Such interventions are rarely informed by scientifically-based insights or methodological sophistication. Rather, they tend to elide and obscure gaps between mainstream scientific research and conventional legal approaches to expert evidence.

For reasons explained in this article, our system of accusatorial trial has not managed scientific evidence well. This observation is particularly important given the increased state reliance on forensic science evidence in recent years. We argue that the criminal legal system's stubborn persistence with traditional adversarial processes tends to blind judicial officers to knowledge, restricts the provision of feedback about accuracy and system performance, and thereby impedes institutional learning. Indeed, institutional inertia, hierarchical deference, technical illiteracy and institutional biases seem to make it difficult for judicial officers to recognise or respond to fundamental epistemic problems with forensic science evidence.

A A Case Study and a Few Caveats

Our decision to focus on a single case permits us to demonstrate some of the failures suggested in the broader literature, but it simultaneously imposes methodological limitations. It might fairly be said, for example, that this case is not representative of contemporary litigation. This section therefore explains both our selection of JP and the reliance that we place upon it in the ensuing analysis.

First, and perhaps most importantly, in Australia as in cognate jurisdictions, there have been relatively few challenges to (non-DNA) forensic science evidence, including latent fingerprint evidence. (10) For a multitude of reasons, including resource constraints and a skills deficit at the criminal bar, methodologically sophisticated challenges to forensic science evidence are exceptionally rare. The infrequency of serious challenges does not reflect the validity and reliability of procedures (or methods) in regular use by the state. To the contrary, following a multi-year review of the forensic sciences, the National Research Council ('NRC') of the United States ('US') National Academy of Sciences (the Academy'), in its Strengthening Forensic Science in the United States: A Path Forward report ('NRC Report'), concluded:

With the exception of nuclear DNA analysis, however, no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source. (11)

It is the exceptional nature of JP--a rare challenge to the long venerated 'science of fingerprint examination' (12)--that makes this case both informative and revealing.

The case of JP is illuminating because, more than a century after the introduction of latent fingerprint evidence, it represents the first sustained attempt to contest such evidence--both the procedures used and the strength of conclusions drawn--in an Australian criminal proceeding. (13) JP is the first substantial challenge to the underlying procedures of fingerprint identification despite longstanding legal reliance, massive expansion of its usage, and technological developments. This relatively late challenge to latent fingerprint evidence comes on the heels of a series of recent authoritative scientific reviews (such as the NRC Report) that question fingerprint examiners' methodology, expression of results, and routine exposure to domain-irrelevant information (such as the identity or criminal history of the suspect). (14) Few of these issues had previously been raised or recognised in legal processes, despite routine reliance on latent fingerprint evidence as definitive proof of identity for more than a century.

Close consideration of JP reveals 'gaps' between mainstream scientific knowledge and the information presented in expert reports and courtroom testimony These gaps usually pass unrecognised within criminal litigation. Further, JP suggests that even when gaps are exposed, many forensic scientists, lawyers, and judges seem incapable of recognising their evidentiary implications for the case and beyond. (15) This case is...