Communicating forensic scientific expertise: An analysis of expert reports and corresponding testimony in Tasmanian courts

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Communicating forensic scientific expertise: An analysis of expert reports and corresponding testimony in Tasmanian courts Carmen A. Reid , Loene M. Howes ⁎

School of Social Sciences, College of Arts, Law and Education, University of Tasmania (UTAS), Private Bag 22, Hobart, Tasmania 7001, Australia

ARTICLE INFO

ABSTRACT

Keywords: Forensic science Forensic studies Expert reports Expert testimony

Forensic criminology examines the use of forensic science in society. Justice can be hampered, for example, if the communication of forensic scientific findings is unclear or misleading, even if unintentionally. Although various recommendations guide the communication of forensic science, it is unclear whether they are reflected in practice. This study explored the communication of forensic biology in 10 cases of major crimes against the person heard in the Tasmanian Supreme Court, where the standard practice is to issue brief summary reports in the first instance. The content of expert reports and corresponding testimony was analysed to determine its adherence to recommendations outlined in standards, practice notes, and research. While reports were found to be very brief, testimony elaborated on all major elements. Mostly elicited by the prosecution, some elements were volunteered by expert witnesses, or raised by defence. Overall, expert evidence in courts—but not reports (due to the use of brief summary reports)—largely adhered to recommendations. Further research is needed to determine the prevalence and effectiveness of alternative approaches to communication that were identified in certain cases.

1. Introduction Forensic science has become a routine aspect of the justice process. Scientific advancement in recent decades has increased the role and impact of forensic science in police investigations, trials, and coronial inquests [1]. The most prominent example of such development is DNA profiling, which is regarded as the gold standard of scientific evidence [2]. In under 25 years, it developed from a contested scientific practice to a relied upon and taken-for-granted method [3]. Even so, DNA evidence is not infallible [4,5]. For criminal justice practitioners, the increased use of forensic science in the criminal justice system necessitates forensic awareness [5], as well as scrutiny of admissibility standards for such evidence in court [6]. For forensic scientists, it necessitates research both to validate techniques [7] and to communicate clearly to justice practitioners [8]. Best practices in these areas are still developing in response to important critiques of forensic science [2,9,10]. Forensic scientific findings are typically presented in a written report. If the case proceeds to trial, forensic scientists can be asked to give testimony based on the report content [11]. Internationally significant publications have identified several problems with forensic science including its communication through expert reports and subsequent testimony [2,9,10]. Although it is difficult to quantify the extent to which ⁎

the communication of forensic science has been implicated in wrongful convictions, ten years ago, a key study in the US found that forensic scientific testimony had been provided in 156 cases where wrongfully convicted people were later exonerated [12]. Researchers located 137 of the trial transcripts and of these, 60% contained testimony that was deemed to be flawed or invalid because it included, for example, inaccurate frequencies or statistics, the use of statistics or verbal expressions without empirical support, and unsupported conclusions (e.g., that the evidence came from the defendant). Similarly, in England and Wales, forensic evidence was implicated in 32% of the 218 cases that were successfully appealed over a 7-year period [13]. In Australia, research has identified 71 cases of wrongful conviction, of which 31% (22 cases) included forensic evidence that was misleading [4]. To ensure that the use of forensic science does not contribute to miscarriages of justice, there is a need for research that focuses on the communication of forensic science findings and expert opinion. This article reports the findings of a study that examined the communication of scientific evidence in expert reports and corresponding testimony. The study is located within the emerging field of forensic criminology [14], which focuses on the use of forensic science in society as the object of research. The article first considers how forensic expertise is socially constructed and used in the criminal justice process and reviews the findings of previous studies that have examined expert

Corresponding author. E-mail addresses: [email protected] (C.A. Reid), [email protected] (L.M. Howes).

https://doi.org/10.1016/j.scijus.2019.09.007 Received 17 May 2019; Received in revised form 23 September 2019; Accepted 29 September 2019 1355-0306/ © 2019 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Please cite this article as: Carmen A. Reid and Loene M. Howes, Science & Justice, https://doi.org/10.1016/j.scijus.2019.09.007

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reports and testimony. It then reports on the communication of forensic biology in 10 cases of major crimes against the person heard in the Tasmanian Supreme Court. The study examined expert reports and corresponding testimony from these selected cases of major crime. It aimed to determine whether the expert reports and testimony included the types of information recommended by practice notes from courts, forensic standards, and research. The study contributes empirical research about current practices and identifies ways to improve the communication of forensic science in practice and research.

2.2. Expert reports Research has identified inconsistencies in the type of content included in expert reports by different jurisdictions, laboratories, and scientific disciplines [24]. In the US, some expert reports have been dubbed ‘certificates of analysis’ for their omission of methodological information, conclusions, and limitations of analyses [24]. In Australia, expert reports have also been found to be lacking in crucial content [7]. Issues identified with reports (e.g., of DNA analysis and forensic examination of glass) included omitting information about the assumptions and limitations of scientific methods [21,25]. These empirical studies support Recommendation 2 of the NAS Report [2], which highlighted a need for greater standardisation of the type of content provided in court reports (by using templates) and of the terminology used to express opinion (so that the uncertainty associated with results would be made clear). In 2013, Standards Australia published a document, Forensic Analysis: Part 4 – Reporting [26], outlining the necessary elements to be included in expert reports. Additionally, practice notes (produced by e.g., the Supreme Court of Tasmania [27] and the Federal Court of Australia [28]) outline expected report content. In terms of expressing opinion with requisite uncertainty, the Australian and New Zealand Policing Advisory Agency and National Institute of Forensic Science [29] published an introductory guide to evaluative reporting. This reflects an international trend (see e.g., European Network of Forensic Sciences Institutes [30]) towards reporting likelihood ratios, which are statistics used to express the likelihood of one hypothesis as opposed to another. Additionally, researchers have made detailed suggestions about the elements to be included in expert reports. These include practical and scientific information, such as forensic laboratory details, a list of exhibits, chain of custody information, descriptions of methodology and its limitations, descriptions of data collected, and procedures for data collection and analysis [6,31]. Recommendations have also been made to assist readers with understanding the report by using terms that adequately disclose uncertainty (i.e., not reporting in absolute terms such as with ‘100% certainty’ as was discussed in The Fingerprint Inquiry [9]), alerting readers to any relevant scientific controversy, explaining limitations and potential sources of error [23], and referring to measures taken to reduce biases [6]. Additionally, recommendations to enhance reader ease include a statement of the purpose of the report, instructions for the use of the report, a comprehensive summary, adequate information about each part of the process presented in a logical sequence [32], and providing and defining the whole scale used to indicate the strength of evidence [33]. Overall, most recommendations currently suggest including more information in expert reports [34] in ways that facilitate understanding by laypeople [21]. It is important to elaborate and provide links for laypeople because they do not have the background knowledge of experts [35]. While brevity is valued in science, if reports are not transparent about the limitations of methods, techniques, and opinions, it is unlikely that lay readers such as legal counsel will be aware of them, leaving it to chance that these matters will be raised in court [6]. Research has documented several reasons why police officers and lawyers would not necessarily contact forensic scientists for further information even if the meaning of the expert’s report (including any associated statistics [22]) was unclear to them. For police officers, these reasons include not knowing who to contact and the perception that doing so would take scientists away from their laboratory work [36]. For lawyers, these reasons include time and budget pressures [22]. Even if more detailed reports can be requested, police investigators and legal practitioners may not request them, with potential consequences for their use in decision making in investigations and the presentation of such evidence in court [8,22,36]. Notably, in response to a recent challenge by the defence to the admissibility of fingerprint evidence, the New South Wales (NSW)

2. Literature review 2.1. Forensic criminology Forensic criminology [14], also known as forensic studies [15], is concerned with understanding the social processes that unfold between the crime scene and the court room, to achieve deeper understanding of criminal justice practices [14]. Past miscarriages of justice and ideas of the sociology of science have helped fuel this area of research. Most forensic disciplines were not developed within the scientific community, but rather, within the criminal justice system to assist in the investigation of crime [16] and prosecution and defence of those at trial [17]. Science and law are two institutions that possess significantly different aims and commitments [3]. The goal of research science is to find objective truths; it looks forward and aims to build upon past findings to develop new ones in the search for fact [3]. On the other hand, forensic science—due to its role in law, which looks back and uses precedent—aims to contribute evidence that advances an argument to convict or acquit a person ‘beyond reasonable doubt’. This does not include the achievement of objective facts, but rather, facts that are reasonable given the circumstances of a specific criminal case [3]. Accordingly, forensic scientists are subject to various constraints. They face organisational pressures, such as the need to analyse samples and present findings in a timely manner for the court, in line with the events of a case [3]. Evidence only comes into being as crimes are committed and legal disputes unfold; it is not available before the fact—as research evidence often is [3,14]. Unlike scientists in research fields, those in forensic science—apart from DNA—have not had to demonstrate reliability through the replication of studies [3,16]. This means that although forensic science is subject to human error, it may never achieve the kind of ongoing communal scrutiny and self-correction that characterises research science [3,16]. Despite these limitations, forensic science is placed alongside other forms of evidence. Judges construct the courtroom as an observational space within which expert vision can extend to laypeople and be easily understood when explained in basic detail [18]. Forensic science is regarded as capable of determining definitive truth and achieving correct and just legal outcomes where other evidence cannot [3,19]. Popular culture presents a view of forensic techniques such as DNA typing as being flawless in their ability to ‘match’ crime scene evidence to its original source. Most courts have accepted this assumption [20] and are disinclined to learn more about the instability of scientific knowledge [16]. Problematically, forensic scientific evidence also holds a ‘special aura of credibility’ that is expected and valued by jurors to justify a conviction [19]. Moreover, it is at the discretion of the jury as to the importance and weight given to forensic evidence within a trial [7]; therefore, it is gravely important that such evidence and its strength is well understood. When complex and technical scientific evidence is provided, it presents challenges for lawyers, judges, and jurors who may have limited scientific proficiency [21]. Lawyers who lack forensic awareness, have limited time for pre-trial meetings with forensic scientists and face budget constraints may not be well equipped to examine or cross-examine forensic scientists [22]. Consequently, forensic scientists may not always be afforded the chance to communicate their results and opinions effectively during a trial [8,23]. 2

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Police Force revised their expert reports. Even though the expert testimony in that case provided more detail than did the report [11], reserving detail until an expert testifies in court is too late to be helpful in earlier stages of the criminal justice process, such as the police investigation. Ultimately, the fingerprint revisions resulted in a change from a 3- to an 8-page report, which includes substantially more detail, better reflecting the Australian Standard Forensic Analysis: Part 4 – Reporting and the NSW Expert Witness Code of Conduct [11]. Some of the information added explicitly outlines some key information about methodology, limitations, and what cannot be concluded from the presence of fingerprint evidence.

ratio or a random-match probability) as the culpability of the defendant [19]. This misinterpretation was coined the ‘prosecutor’s fallacy’ [40]. In a study using the likelihood ratio to express the value of forensic evidence in a mock case, approximately 92 percent of judges, 80 percent of lawyers and 58 percent of expert witnesses succumbed to the prosecutor’s fallacy [39]. While criminal justice practitioners may gain familiarity with likelihood ratios now that they are increasingly used, jurors still find them difficult to understand [38]. 2.4. The current study Prior research in forensic studies has made valuable contributions towards comprehensible communication of forensic evidence in written reports and subsequent testimony. Communication of evidence that is understandable for laypeople contributes to better evaluation of the evidence and helps promote fair and just outcomes of trial. However, while previous research has analysed expert reports for the presence of essential information [11,21,24,25,31], little research has examined both expert reports and the corresponding testimony at trial, although this issue was the subject of discussion by Edmond and colleagues [11]. The current study explicitly examined how forensic biologists’ expert reports corresponded with associated testimony in a sample of 10 cases. The study aimed to do this by examining the content of expert reports and expert testimony, beyond the expressions used to convey the strength of the evidence, to explore opportunities for forensic scientists to elaborate on key aspects of their reports at trial. The purpose of this study was to examine whether expert reports and testimony provided by forensic biologists in the Supreme Court of Tasmania adheres to standards, practice notes, and recommendations from legal and criminological research, and whether experts have adequate opportunity to explain their findings in court.

2.3. Expert testimony Research focussing specifically on testimony has made several recommendations. Most prominently, when providing expert testimony, forensic scientists should be allowed to explain their adherence to each requirement of court-imposed codes of conduct [23], such as practice notes of the relevant court [27,28]. Similarly, scientists should be ‘epistemologically modest’ in stating their opinions, so that they do not convey a greater strength of evidence than can be justified [6]. However, forensic scientists are constrained in their ability to explain their expert opinion and provide their reasoning, unless they are asked suitable questions by prosecution or defence counsel [22,8]. In one study, forensic biologists expressed concern that their evidence should be expressed conservatively but that it could be made to look too strong or too weak by prosecution or defence [8]. The study highlighted the perspective that cross-examination by defence could be beneficial, to provide a more balanced view of the evidence if this had not been achieved by prosecutors during examination. This reflects a shared obligation of forensic scientists and legal practitioners to ensure that forensic scientific evidence is presented in a comprehensible way at trial [6,8,22]. Expressing the strength of expert evidence has been a pervasive issue examined in research. Some expressions can unduly persuade and influence lay people and exaggerate the capabilities of the science [7]. For example, the use of the term ‘match’ to express a degree of correspondence between a sample taken from a suspect and one taken from the crime scene can be misleading [37]. The term ‘match’ suggests to juries that the defendant is the source of the crime scene evidence, to the exclusion of other possibilities. The use of terms such as ‘match’ and ‘consistent with’ have been queried in the comparison of hair, fingerprints and fibres [2]. However, the term ‘match’, may simply indicate similarities in certain features of the samples that suggest that further testing may be beneficial [20]. In the case of DNA profiling, it may refer to corresponding peaks at some or all of the loci (sites) compared. If there is a match at the peaks of 21 loci compared, the number analysed in some Australian laboratories, it presents extremely strong evidence that the two samples came from the same person (or an identical twin). Nevertheless, there exists the possibility of laboratory errors, such as mislabelling, contamination, or loss of samples. Additionally, errors can occur when low amounts of DNA are detected, or complex mixtures are interpreted [2]. Moreover, it is important to note that the presence of a person’s DNA at a crime scene is a form of circumstantial evidence. Its presence does not mean that the person committed the crime. Further, it is not possible to determine when or how the DNA was deposited. It is important that jurors are made aware of this kind of information so that they do not idealise science and believe it to be infallible. Researchers have examined the use of statistics to accurately convey the weight of evidence, incorporating uncertainty appropriately [38]. However, most people possess poor statistical reasoning abilities [37,39]. Probabilities expressed about finding evidence from a particular source, in line with a prosecution hypothesis, may be interpreted by laypeople as the probability of the hypothesis itself being true [7]. This is the error of equating the statistic provided (whether a likelihood

3. Methodology The study received ethical approval from the Social Sciences Human Research Ethics Committee Tasmania. Initially, letters of support for the project were received from the Supreme Court of Tasmania and Forensic Science Service Tasmania (FSST). Following the formal application process, letters of approval were received from the Supreme Court of Tasmania and the Department of Police, Fire and Emergency Management. 3.1. Sampling procedure and sample After consultation with the Supreme Court of Tasmania and FSST, the scope of this exploratory study was limited to expert communication in cases of major crimes against the person involving forensic biological evidence. A purposive sample was obtained from FSST and included expert evidence from ten cases heard in the Supreme Court of Tasmania between 2017 and 2018. The cases were chosen for their recency and relative complexity (in comparison with more routine volume crime cases). During the sampled time period, the laboratory was making a transition in their statistical evaluation approach to the use of likelihood ratios; therefore, only some of the cases include this type of assessment. The sample of 10 cases included forensic biology evidence, which consisted of 12 expert reports and 10 corresponding court transcripts (see Table 1). Reports and transcripts were not intended to be representative of the population of cases including biological evidence. Neither reports or transcripts were publicly available. Expert reports were ‘summary reports’ which state in the opening paragraph that ‘a full report can be provided on request’, although it is reportedly unusual for such a request to be made. Transcripts consisted only of the portion containing expert testimony; not the cases in their entirety. Most cases included one report and one transcript, although two cases had an initial report and a follow-up, written at a later date. Reports 3

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Table 1 Sample and sample characteristics. Case

Year

Pages

Reports

Type of forensic evidence

Expert/sa

1 2

2018 2017

25 130

1 2

1 2, 3

3 4 5 6 7 8 9 10

2017 2018 2017 2017 2018 2017 2018 2018

7 28 9 22 86 12 27 69

1 1 1 1 1 1 1 2

Biological examination of Sexual Assault Investigation Kit (SAIK), DNA profiling, search on DNA database Biological examination of items and stains from crime scene, DNA profiling, BPA (Bloodstain Pattern Analysis), search on DNA database, hair examination Biological examination of items from crime scene, DNA profiling, search on DNA database Biological examination of items from crime scene, DNA profiling, Search on DNA database Biological examination of items and stains from crime scene, DNA profiling, Search on DNA database, Biological examination of SAIK, DNA profiling, search on DNA database Biological examination of items and stains from crime scene, biological examination of body parts, DNA profiling, BPA Biological examination of items from crime scene, DNA profiling, search on DNA database, BPA Biological examination of items from crime scene, DNA profiling, search on DNA database Biological examination of items and stains from crime scene, DNA profiling, search on DNA database

3 1, 4 1 5 4, 5 6 5 1, 5

a In the majority of cases, reports named two forensic scientists, one with responsibility for biological examination and one for DNA profiling. The numbers provided in the table above refer only to those who testified at court.

and transcripts were de-identified by FSST by removing the details (e.g. name and address) of complainants and defendants. On average, reports were 10 pages long (range = 4–27 pages) and transcripts of expert testimony were 25 pages long (range = 7–130 pages). They included reference to biological examination of items from the crime scene (n = 8), stains from the crime scene (n = 4), Sexual Assault Investigation Kits (SAIK; n = 2), and body parts (n = 1). Additionally, reports and testimony included the following evidence types: DNA profiling (n = 10) and associated searches on DNA databases (n = 9); Bloodstain Pattern Analysis (BPA; n = 3); hair examination (n = 1); and textile damage analysis (n = 1).

For expert testimony, the fifth category (see Table 2) was also coded. Additional notes were made in this category about who elicited the information (the prosecutor, the defence lawyer, or the judge) and at what stage of examination it was discussed. Finally, data for each expert report and transcript of testimony were compiled into a single document. This lengthy process facilitated the identification of patterns in the information that was included or omitted across texts and cases. 4. Results In general, summary expert reports and testimony provided corresponding information. However, while limited detail was provided in the summary reports, testimony afforded the opportunity for elaboration, allowing content to better reflect the recommendations outlined in standards, practice notes and research. The key findings are presented below for each category of information in reports and testimony. Where relevant, illustrative quotes from testimony are included.

3.2. Content analysis Content analysis is regarded as an unobtrusive method, in that it does not involve participant interaction [41]. It is suitable for analysing both written and verbal communication. Recurring, easily-observed features of the communication are systematically coded to ascertain the content, structure, patterns and themes commonly present in the text [41]. Following previous research on expert reports [21,24,25], content analysis was conducted on the sample of expert reports and corresponding testimony. Prior to analysis, a codebook was created containing a list of content to be included in both expert reports and testimony, by drawing necessary elements for inclusion from relevant sources. These included standards, practice notes, and research. The current study considers elements of report content that are most relevant to the expert testimony; therefore, it omits report-specific content such as summaries and report usage guidelines. The elements of content identified as codes for the study were grouped into broad categories of information: scientist and agency information; examination and exhibit information; methodological information; results, opinions and conclusions; and testimony-specific characteristics (see Table 2).

4.1. Scientist and agency information Details of the scientist and agency-related information that was included in expert reports and testimony can be seen in Table 3. Expert reports included the expert’s name, title, and contact details. Reports did not include information about qualifications and experience as this is provided only in full reports. However, expert testimony in all cases included the expert witness’s full name, title or occupation, workplace, time employed in role, and academic qualifications. Eight cases included information about experts’ experience (for how long they have practiced) and three about their background (at what agency and in what discipline they have practiced). All expert reports featured the reporting scientist’s agency information. This included the agency name (Forensic Science Service Tasmania [FSST]), address, and contact details. Similarly, in all cases, expert testimony mentioned some agency information. Agency location was provided in five cases, with more detail on the nature of the agency and its disciplines in four cases. The glossary of each report provided a number to indicate adherence to a specific procedure or protocol. However, adherence to protocol or practice notes was not discussed within expert testimony.

3.3. Data analysis Expert reports were numbered from 1 to 12 and ten corresponding transcripts of forensic expert testimony were numbered from 1 to 10, in the order of receipt from Forensic Science Service Tasmania (see Table 1). Data analysis was undertaken in three phases. First, information that corresponded to the first four broad categories shown in Table 2 was highlighted using a colour-coded system in expert reports and transcripts of expert testimony. Un-highlighted sections consisted only of information unrelated to the codes, such as table headings (in reports) and general exchanges between practitioners (in testimony). Next, more detailed coding within categories, of each specific type of information was undertaken using physical copies of the codebook, reflected in Table 2. When a code was identified in text, this was noted with a brief description, a direct quote, and the relevant page numbers.

4.2. Examination/exhibit information Details of information about examinations and exhibits included in reports and testimony can be seen in Table 4. Expert reports stated that details of the examination requests made by police investigators could be provided upon request. In testimony, one case included an explicit statement of examination requests: ‘…we had a sexual assault investigation kit…and we were [asked] to examine that for the presence of semen…’ (Case 1, testimony). Similarly, the purposes of examinations 4

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Table 2 Codes for expert reports and testimony. Category Scientist and agency information Examination/exhibit information

Methodological information

Results, opinions and conclusions

Testimony-specific characteristics

Code

qualifications and experience (background, training, proficiency testing) [21,25–27,31] • Scientist’s agency [21,25–27,31] • Scientist’s of adherence to protocols and practice notes [8,21,23,25,28] • Statement of examination requests made [31] • Statement of examinations [21,25] • Purpose of propositions or hypotheses under consideration [8,31] • Statement of each exhibit analysed (ID number, description, source, condition) [2,21,25,26,31] • Mention of whether exhibit is from known origin (e.g., database search, sample submitted by investigator) or questioned origin (e.g., from • Statement crime scene) [2,23,26,31] and amount of DNA material from exhibits where traces are significantly low [8,23,31] • Quality of custody information for each exhibit [21,25,26,31] • Chain basics (definitions and explanations of the science) [2] • Foundational of materials used for analysis [2,21,25,31] • Description of tests conducted (biological examination) [8,21,25,26,31] • Description of the procedures by which examinations or comparisons were conducted (including peer review) [8,21,25,26,31] • Explanation of whether the method is widely accepted as standard [31] • Statement likely limitations of the method and relevance of limitations to the case at hand [26,31] • Any about testing of expertise and validation [21,26,31] • Information of results for each exhibit and observations of similarities and dissimilarities between samples compared [2,21,25,26,31] • Description each item analysed, an indication of which hypothesis was supported [23,31] • For of opinion or inference from analyses, set out separately from findings and with reasons [2,21,25,26,28,31] • Statement explanations and reasons for their rejection [26] • Alternative of observations and tests are not over- or under-stated [26] • Value/weight of the reporting scale employed (whether numerical or verbal) [31] • Explanation of any population databases used (e.g. name, region, how data is gathered) [23,31] • Description of conclusions and implications of analyses [2,23,26,31] • Discussion of analogies by scientists to explain to the jury [8] • Use define complex terms [8,26] • Practitioners do not use scientific terms unless already explained by scientist and makes more sense to use the precise term [8] • Lawyers questions are not insisted upon by counsel when questions indicate complexity (unless opportunity to explain is then provided) • Brief/closed [8] • Information elicited by (prosecutor, defence lawyer, or judge)

Note. Numbers in square brackets refer to the references from which codes were drawn. The use of these codes does not suggest that consensus exists amongst practitioners about the inclusion of all elements in their reporting.

were not outlined within expert reports. However, in six cases, these were stated within expert testimony. In cases that involved evaluative reporting (using likelihood ratios to compare one hypothesis relative to another), the propositions under consideration were briefly stated in reports as: ‘H1: Person A is a contributor’ and ‘H2: Person A is not a contributor.’ Similarly, in these cases, the propositions under consideration were mentioned in testimony when presenting the results. All expert reports and testimony provided details of each exhibit submitted for examination, including source and condition. This included identification numbers, descriptions of condition and sources. In four cases, the jury was provided with copies of the expert report (or an extract thereof). When this occurred, information such as exhibit numbers and descriptions were referred to more briefly in testimony. Similarly, all expert reports and testimony provided information on the origin of exhibits. Exhibits of known origin (e.g., a DNA reference sample from a suspect) were distinguished from those of questioned origin (e.g., a sample taken from a crime scene) by mentioning it as a

reference sample and stating the name of the person who provided the sample. In three cases, expert reports provided explicit indications of when DNA material derived from exhibits was significantly low. This was stated through ‘insufficient human DNA obtained/detected/recovered to proceed with DNA testing’ or upon the presentation of results, where it was stated that there were ‘no reliable conclusions regarding possible contributors due to low DNA levels.’ In testimony, three cases indicated lower amounts of DNA upon the presentation of results, when it was noted that DNA testing could not be undertaken, or a result could not be determined due to low or insufficient DNA levels. Reporting of low levels of DNA would only be anticipated in cases when it is a relevant consideration. Thus, lack of reporting did not indicate omission. Expert reports stated that the chain of custody information for each exhibit could be provided on request. In two cases, chain of custody information was discussed for some exhibits. In one of these cases, testimony briefly stated that the forensic scientist had attended the crime scene to take samples for testing, implying that other personnel

Table 3 Scientist and agency information. Code

Sub-code

Expert reports

Expert testimony

Case/s

Expert/s

Scientist’s qualifications and experience (background, training, proficiency testing)

Qualifications Experience Background Training Proficiency testing Name Location/address Contact details

0/12 0/12 0/12 0/12 12/12 12/12 12/12 12/12 12/12

10/10 8/10 3/10 4/10 0/10 10/10 5/10 0/10 0/10

1–10 1–2, 4, 6–10 2, 8, 9 2, 6, 7, 9 1–10 1–10 4–6, 9, 10 1–10 1–10

1–6 1–6 2, 3, 5, 6 2, 3, 4, 5 1–6 1–6 1, 4, 5 1–6 1–6

Scientist’s agency Statement of adherence to protocols and practice notes

5

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Table 4 Examination/exhibit information. Code

Expert reports

Expert testimony

Case/s

Expert/s

Statement of examination requests made Purpose of examinations

0/12 0/12

1/10 6/10

1 1–5

Statement of propositions or hypotheses under considerationa Mention of each exhibit analysed (ID number, description, source, condition) Statement of whether exhibit is from known origin (e.g., database search, sample submitted by investigator) or questioned origin (e.g., from crime scene) Quality and amount of DNA material from exhibits where traces are significantly low Chain of custody information for each exhibit Foundational basics (definitions and explanations of the science)

4/5 12/12 12/12

3/4 10/10 10/10

1 1, 2, 6, 7, 9, 10 2, 4, 8, 9 1–10 1–10

3/12 0/12 12/12

3/10 2/10 10/10

4, 7, 10 1, 7 1–10

1, 4, 5 1, 4, 5 1–6

1–5 1–6 1–6

a The sample of cases reflects a period of transitioning to reporting using likelihood ratios (LRs). Four cases used this approach to reporting (and of those one had two expert reports). In one case, the amount of DNA obtained was insufficient for testing, and therefore the testimony in that case did not report hypotheses and LRs. In another case, DNA analysis was not undertaken and therefore hypotheses were not presented.

were not involved in the chain of custody. In another case, the chain of custody was briefly mentioned, in that items had been delivered to the laboratory by police. In all cases, expert reports and testimony included the foundational basics of the science specific to the case. All expert reports included glossaries, to define the scientific terms associated with DNA, BPA, hair and textile damage expertise. In testimony, typically, the nature of DNA and rich sources of it were outlined. Other information presented less often included the identification capabilities of DNA, its hereditary nature, where DNA is found, transfer DNA, the 21 areas of observation, DNA shedding, and why DNA is useful in a forensic setting. In one case, expert testimony included a PowerPoint presentation to explain DNA with an example of a profile. For the two cases featuring BPA in testimony, foundational explanations included information about how the appearance of blood patterns can be used to infer how blood was deposited and an overview of the different mechanisms of deposition. In the case that included hair examination, little foundational explanation of the associated science was given. However, the scientist stated that although qualified to testify basic results, hair examination was not their specialist area.

reader to locate the relevant information. Reports simply stated the biological substance found on an item, and different substances were associated with different tests. For example, ‘human blood detected’, may indicate that a ‘Hemastix’ screening test for blood [BM06] or a confirmatory test for human blood [BM27] was conducted. However, for an unfamiliar reader, it may be difficult to ascertain which test was used and therefore to locate the relevant glossary information about that test. In five cases, expert testimony included the names of the tests used in biological examination, the purposes of these tests, how they work, and a description of screening and confirmatory tests. One case featured a SAIK that included only slides and required microscopic analysis rather than biological testing. Expert reports did not include any description of the methods and procedures used in analyses. We have been advised that following the sampled time period, an appendix was added to reports to describe these types of processes. Although reports in the sample did not contain such description, it was included in eight cases of expert testimony. For biological examination, this most commonly included photographing an item, visually examining it, swabbing, testing it using screening and confirmatory tests, and packaging it for DNA profiling. For DNA profiling, procedural descriptions generally included extraction, quantifying and copying processes, followed by running the DNA through a profiling instrument. The most comprehensive description of procedures was given in the case that used a PowerPoint presentation. The first sentence of the glossary states that the test methods used routinely at FSST are widely used and accepted in the forensic community. In expert testimony two cases stated that methods were widely accepted: ‘the [21] locations are just fairly standard through the forensic community worldwide’ (Case 1, testimony) and ‘[the method is] scientifically agreed upon, Australia wide as well as worldwide’ (Case 4, testimony). Expert reports did not mention limitations of the methods used. In testimony, seven cases included mention of limitations. In one case, limitations included differential DNA shedding of different people,

4.3. Methodological information Details of methodological information included in reports and testimony can be seen in Table 5. Expert reports included reference to a procedure number in the glossary. They did not explicitly describe the materials used for either biological examination or DNA profiling analyses. In expert testimony, nine cases included description of some of the materials used for biological examination. This included cotton swabs, Eppendorf tubes and plastic tube bags. In three of the cases, testimony included mention of the materials of DNA profiling, including a chemical solution and the DNA profiling instrument. Expert reports included limited description of tests conducted, although a list of tests was provided in the glossary. However, the body of the report did not include reference to a procedure number to assist the Table 5 Methodological information. Code Description of materials used for analysis Description of tests conducted (biological examination) Explanation of the procedures by which examinations or comparisons were conducted (including peer review)

Statement of whether the method is widely accepted as the standard Any likely limitations of the method and relevance of limitations to the case at hand Information about testing of expertise and validation

Sub-code

Expert reports

Expert testimony

Case/s

Expert/s

Biological examination

0/12 0/12 0/12 0/12

9/10 5/10 8/10 7/10

1–6 1–5 1–5 1–5

0/12 0/12 12/12 0/12 0/12

6/10 0/10 2/10 7/10 1/10

1, 2, 4–10 2, 6, 7, 9, 10 1, 2, 4, 6, 7–10 1, 2, 4, 6, 7, 9, 10 1, 2, 4, 6, 8, 9 N/A 1, 4 2, 5–7, 9, 10 2

DNA profiling Peer review

6

1–6 N/A 1, 4 1–5 2, 3

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include explanations about the possible reasons for the presence of biological material. Unless specifically asked, scientists do not comment on how material may have been deposited as they are not typically provided with the case information that would be necessary to do so. In five cases, testimony discussed alternative explanations, with the defence introducing discussion of plausible and non-incriminating explanations for the presence of the DNA. In two cases, secondary transfer was suggested as an alternative explanation. For example:

which may impact the ability to obtain DNA profiles, and the inability of DNA profiling to provide information about the location that the DNA came from. Other limitations included that a DNA profile does not provide information about how it was deposited, the time it was deposited, and for how long it had been on an item. Finally, the use of ‘wet swabs’ to sample DNA from an item was considered a possible limitation as it might dilute the DNA evidence. The limitations mentioned were expressed in general terms (it was not suggested that they were at issue in the cases at hand; the purpose was to make jurors aware that DNA evidence is not infallible for a range of reasons). Neither expert reports nor testimony included any information on the expertise testing of scientists and validation testing of methods, with the exception of one case. In this case, the scientist stated that the technique had been validated internally by Australian laboratories, and ‘the expected results were obtained’ (Case 2, testimony). The laboratory accreditation requires that methods are validated before they can be used; however, this was not made explicit in reports or testimony.

Defence: …if…person B had shaken hands with person A and then touched the steering wheel, is that a possible way as to how [DNA] would have got there? Scientist: Yes, that is a possibility (Case 8, testimony). Other alternative explanations included differential shedding of DNA by different people, to explain why a person’s DNA could be on someone else’s item of clothing, in the same amount as for the wearer of the clothing. In one case, it was suggested that during a fight, DNA might have been deposited on an item in a particular transfer fashion. Additionally, gravity—rather than external force—might have explained the cause of a particular blood pattern. Within all expert reports and testimony, scientists were conservative when they indicated the value and weight attributed to observations and tests. For example, in one case including BPA, the expert remained conservative in relation to observing particular blood patterns as spatter stains: ‘…I certainly wouldn’t be putting my hand on my heart and saying that it is [a spatter stain], because as I said, I don’t know…’ (Case 7, testimony). The same uncertainty was maintained as to the number of blows required to cause blood patterns: ‘…It probably would be more than one, just given the amount of stain there but as for how many I couldn’t tell you. Couldn’t say.’ (Case 7, testimony). In another case, uncertainty was maintained in regard to the source of DNA of a profile being blood: ‘[exhibit] 7(1) was DNA profiled but we didn’t do the human blood test on it. From that we can infer that 7(1) could also well be human blood but we can’t confirm that because we didn’t actually do the test but in all likelihood it is, yes.’ (Case 9, testimony). Uncertainty was conveyed through likelihood ratios and by reporting inconclusive results. Scientists also ensured that they were conservative in the language they used. For example, when a prosecutor asked if the purpose for biological examination of a SAIK was to determine whether sexual intercourse had occurred, the scientist responded: ‘Whether sexual intercourse could have occurred, yes.’ (Case 1, testimony). In eight cases, the term ‘match’ was used for reporting DNA profiling results within expert testimony. In six of the cases, the use of the term was clarified to explain that a ‘match’ was at the 21 areas of DNA that had been compared. In two cases, the expert witness explicitly defined the term. For example, in one case:

4.4. Results, opinions and conclusions Information about results, opinions and conclusions that was included in expert reports and testimony can be seen in Table 6. All expert reports included descriptions of the results of both biological examination and DNA profiling for each exhibit. In all cases, expert testimony mentioned the results of the tests used in biological examination, for particular substances. For DNA profiling, all testimony included the person profile/s (reference sample/s) with which the DNA profile from the crime scene sample corresponded. In six cases, testimony reported whether the DNA profile was for a single contributor or more than one contributor (mixed profile), and the biological sex of these contributors (referred to as gender). In four cases, expert testimony also mentioned the major profile, for which there was the most DNA in a mixture and a minor profile, with less DNA. However, no information was provided on the specific similarities and dissimilarities of the DNA profiles that had been compared, except in one case where the prosecutor asked the scientist to elaborate on the similarities of a profile at each of the 21 locations analysed. All expert reports featured scientific opinions of inferences that could be drawn from biological examination of each exhibit. In seven cases, expert testimony provided scientific opinions. One of the remaining three cases did not mention opinions and two did not provide opinion as no results were obtained from testing. Factors stated as having led the experts to their conclusions were the appearance of stains on items, including colour and consistency, and the result of the testing for a particular substance. Expert reports did not include any alternative explanations for results because, as laboratory staff explained, the reports do not typically Table 6 Results, opinions and conclusions. Code

Expert reports

Expert testimony

Case/s

Expert/s

Description of results for each exhibit

12/12

10/10

1–10

1–6

For each item, for DNA analysis, an indication of which hypothesis was supporteda Statement of opinion or inference from analyses, set out separately from findings and with reasons Alternative explanations and reasons for their rejection Value/weight of observations and tests are not over- or under-stated Explanation of the reporting scale employed Description of any population databases used

4/5 12/12

3/4 7/10

2, 4, 8, 9 1, 2, 5–10

1–5 1–6

0/12 12/12 12/12 0/12 0/12 0/12 0/12 0/12

5/10 7/10 8/10 5/10 1/10 4/10 0/10 1/10

2, 4, 7, 8, 10 1, 2, 5, 6, 7, 9, 10 1, 2, 4–7, 9, 10 2, 4, 6, 7, 9 2 2, 6, 7, 9 N/A 1

1–6 1–5 1–5 1–5 2; 3 2–5 N/A 1

Discussion of conclusions and implications of analyses

Sub-code

Name Region How data is gathered

a The sample of cases reflects a period of transitioning to reporting using likelihood ratios (LRs). Four cases used this approach to reporting (and of those one had two expert reports). In one case, the amount of DNA obtained was insufficient for testing, and therefore the testimony in that case did not report hypotheses and LRs.

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defined the expert field’s terminology. For example, forensic scientists defined scientific terms such as ‘DNA’, ‘screening test’, ‘confirmatory test’, ‘major profile’, ‘mixed profile’ and ‘fraction’. However, in two cases prosecutors used the term ‘contemporaneous’, a lay term often used in the legal realm, without definition. The term is used by forensic scientists in the course of their work and would be an unfamiliar term to many jurors. In all cases, scientific terms were only used by counsel after the scientist had previously used and defined them or in questioning to prompt discussion of the phenomena. In eight cases, closed-ended questions were used appropriately, in that they were not insisted upon by counsel for inherently complex questions about science. They were used when asking about case numbers, exhibits, and whether items were sent for DNA profiling. In one case, counsel used closed-ended questions for the method and DNA explanation, though the expert witness was allowed to elaborate afterward. By contrast, in two cases, the (same) prosecutor led the presentation of results through closed questions. The expert witness agreed (‘yes’) or disagreed (‘no’). This approach denied scientists the opportunity to explain. Table 8 details the elicitation of information in testimony. In the majority of cases, the prosecution elicited information during their initial examination of the expert witness. This included scientist and agency details, examination requests and the purpose of examinations, exhibit presentation, origin and chain of custody information, foundational basics, materials, tests conducted, method and procedures, results and supported hypotheses, scientific opinions, the likelihood ratio, population databases, and the discussion. Expert witnesses most commonly volunteered information on low amounts of DNA material and in some cases whether methods were widely accepted as the standard. Defence lawyers most often elicited information on scientific expertise, validation testing, alternative explanations, and in some cases the limitations of methods used. The judge elicited information about the likelihood ratio and the representativeness of a population database. Finally, in one case, a jury member was permitted by the judge to suggest a limitation involving ‘wet swabbing’ and dilution.

If it was CSI, we could say: ‘that’s a match’ – but in reality, that’s not quite how it works. What we’ve got then is a match at the DNA profile level, so we’re not talking about a match at the sequence level, where we’ve compared all the DNA, we’re just looking at the DNA profile…. (Case 2, testimony). In all cases the expression ‘not excluded’ was used in testimony for reporting DNA profiling results of mixed DNA profiles where greater caution in interpreting profiles is warranted. Statistics were used for reporting expert opinion in DNA (single and mixed profiles). Due to a change in reporting practices over the sampled time period, the expert reports of the four most recent cases featured a clear statement of both prosecution and defence hypotheses and indicated the supported hypothesis of the likelihood ratio. In the associated testimony of these cases, supported hypotheses were indicated for exhibits. In other reports in which likelihood ratios were not used, conditional probability or random match probability figures were provided to indicate the strength of evidence. In all expert reports an explanation of the reporting scale used was provided. In eight cases, expert testimony included explanations of the statistics provided, albeit briefly in one case. Verbal equivalents to the likelihood ratio were not used in explanations. In one case, the prosecutor’s question highlighted the difficulties laypeople face in interpreting statistical information, while the expert’s response indicated the complexity of concepts and challenges in explaining them: Prosecution: So does that mean that – it’s a hundred billion times more likely that he’s a contributor than someone other than…him? Scientist: No, it means that the DNA profile that we’ve obtained is a hundred billion times more likely. So that the profile itself that we’ve seen is a hundred billion times more likely if he was a contributor to the profile. To go to the step of saying ‘it’s a hundred billion times more likely that it’s him’ that requires a whole lot of other information about the scenario that we just don’t have; all we’re working is the DNA profile. So we can tell you how probable the DNA profile is, given the suggestion that this person may have contributed to it, but we can’t tell you how probable it is that that person left that DNA (Case 2, testimony).

5. General discussion

Expert reports did not describe the population databases used to form likelihood ratios, nor their representativeness to the case at hand. In four cases, testimony referred to databases and their regions. In one case, the name of the database was explicitly mentioned. Expert reports did not include discussion, conclusions or implications of the obtained results. Consideration of the case context is reserved for the courtroom. In all cases, testimony featured such discussion. However, only testimony in one case elaborated on the conclusions or implications of testing.

The purpose of this exploratory study was to examine whether expert reports and testimony adhered to standards, practice notes, and recommendations from legal and criminological research, and whether experts have adequate opportunity to explain their findings. Expert reports and testimony given by forensic biologists in a sample of ten cases of crimes against the person heard in the Supreme Court of Tasmania were used as a data source. Overall, it was found that expert reports were very brief and on their own did not provide enough information to explain the findings to a layperson, according to the criteria set by various practice notes, standards and past research. In part, this was because rather than full expert reports, summary reports are routinely provided. Although the reports advise criminal justice practitioners that they can request full reports, laboratory staff report that such requests are not typically made. Despite this, when providing expert testimony, it seemed that forensic scientists were given ample opportunity to explain their results, with some caveats that will be discussed below. While the finding is relatively optimistic about testimony, it does not eliminate concerns about the brevity of summary

4.5. Testimony-specific characteristics Table 7 outlines testimony specific characteristics. In six cases, an analogy was used in expert testimony to explain concepts to the jury. For example, in two cases, Tattslotto was used to explain the probability of the likelihood ratio: ‘Tattslotto, if it’s got sixty numbers in it, [it’s] got much more chances of having no match than one with twenty or forty numbers in it?’ (Case 1, testimony). In the testimony of eight cases, both counsel and expert witnesses Table 7 Testimony-specific characteristics. Code

Expert testimony

Case/s

Expert/s

Use of analogies by scientists to explain to the jury Definition of complex terms by practitioners Use of scientific terms only after explanation by scientist Brief/closed questions insisted upon by counsel when questions indicate complexity

6/10 8/10 10/10 2/10

1, 3, 4, 6, 7, 10 1, 3, 4–9 1–10 4, 10

1, 3–5 1, 3, 4–6 1–6 1, 4, 5

8

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Table 8 Elicitation of information in testimony. Result category Scientist and agency information Examination /exhibit information

Methodological information

Results, opinions and conclusions

Information

qualifications and experience (background, training, proficiency testing) • Scientist’s of the scientist’s agency • Details of examination requests made • Statement of examinations • Purpose of propositions or hypotheses under consideration • Statement of each exhibit analysed (ID number, description, source, condition) • Mention of whether exhibit is from known origin (e.g., database search, sample submitted by • Statement investigator) or questioned origin (e.g., from crime scene) • Quality and amount of DNA material from exhibits where traces are significantly low of custody information for each exhibit • Chain basics are established (definitions and explanations of simple science) before results • Foundational are provided of materials used for analysis • Description of tests conducted • Description of the procedures by which examinations or comparisons were conducted (including • Explanation peer review) of whether the method used is widely accepted as the standard method • Statement • Any likely limitations of the method and relevance of limitations to the case at hand about testing of expertise and validation • Information of results for each exhibit and observations of similarities and dissimilarities between • Description samples compared each item analysed, an indication of which hypothesis was supported • For • Statement of opinion or inference from analyses, set out separately from findings and with reasons explanations and reasons for their rejection • Alternative • Explanation of the reporting scale employed (whether numerical or verbal) of any population databases used (e.g. name, region, how data is gathered) • Description • Discussion of conclusions and implications of analyses

Elicited by Prosecution Prosecution

Expert witness (one case – prosecution) Prosecution Prosecution (one case – expert witness) Prosecution Prosecution (one case – expert witness) Prosecution and expert witness Prosecution and defence (one case – jury member) Defence Prosecution Prosecution Prosecution (two cases – defence) Defence Prosecution (one case – judge) (one case – expert witness) Prosecution Prosecution (in re-examination)

Note. Information was elicited by the prosecution during examination and by defence during cross-examination, unless otherwise stated.

reports because few cases proceed to trial and of these fewer include expert testimony. For other cases, in which the expert report is nevertheless important, police and lawyers may not have easy access to the level of detail required.

1. The history of the samples as known to the laboratory, both before and after their arrival. 2. A statement identifying all items examined, when where and by whom the examination was performed and indicating the findings, whether or not a DNA profile is obtained. 3. A clear statement setting out the basis upon which any opinion rests and the limitations within which it is expressed [5, p. 54].

5.1. Expert reports Increased pressure exists for laboratories to conform to certain reporting practices. This is readily apparent in Europe, as it would facilitate data exchange within a common area of justice [42]. However, it has been noted that not all forensic scientists and laboratories agree with recommended practices [42]. This diversity of opinion is also relevant in the Australian multi-jurisdictional context. Although the summary expert reports did make use of a template, as recommended by the NAS Report [2], they lacked elaboration on much of the content outlined in Table 2 that has been recommended for inclusion. The findings of this study reflect previous research on expert reports [24,25], with limited information included on the methods and materials, procedures, and limitations of the discipline and techniques used. Some information about this may assist non-scientists to recognise that limitations do exist, rather than holding idealised or unrealistic expectations of science. Brevity can present a problem for a layperson if there is not enough information provided to understand what led the expert to their opinion. In short, omission of these types of details may make laypeople more susceptible to viewing scientific findings as facts [18]. It is noteworthy that in his 2010 report, Inquiry into the circumstances that led to the conviction of Mr Farah Abdulkadir Jama, Justice Vincent recommended that: In cases where DNA testing is carried out for forensic purposes, a full report be provided as a matter of course to the investigating police members and, where the VIFM [Victorian Institute of Forensic Medicine] is involved, to them, setting out,

The brevity of reports may reflect organisational constraints and time pressure faced by forensic scientists [3]. For example, in England and Wales, the use of very brief streamlined expert reports is intended to save time and costs [43]. However, the use of these reports is highly contentious because it does not provide an adequate level of detail for report readers, potentially burdening the defence, and is seen to pose threats to the quality of forensic science service provision [34,43,44]. Therefore, it is incumbent on legal practitioners to request full reports from forensic laboratories when the brief reports do not meet their information needs. However, the issue of who should be responsible for recognizing the need for further information provision is vexed; it is apparent that police investigators and legal counsel do not routinely, or even regularly, request full reports. Previous research has noted that scientists in most Australian jurisdictions are open to discussing their findings with both prosecution and defence [8]. However, lawyers can be extremely time poor and defence lawyers may not feel comfortable discussing their cases with experts whom they view as being associated with the prosecution. Further, the job of explaining expert reports to prosecutors can sometimes fall to the police investigator [36]. Police investigators also reported finding it difficult to comprehend the scientific language of reports and to understand reporting scales used to indicate the strength of evidence [36]. Particularly relevant to this study is the fact that forensic DNA reports were reported as amongst the most difficult to 9

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understand, with many police investigators expressing a preference to contact scientists directly for further explanation. However, such contact is not always possible [36]. The fact that police investigators and lawyers may not seek clarification of reports even when it would be helpful to them suggests a need to include more information from the outset. It would be beneficial for forensic scientists to take the initiative to provide more information within the routine reporting template, in line with recommendations from practice notes, standards and research, given that further detail is rarely requested by police and lawyers regardless of need. This includes: the reporting scientist’s qualifications, experience, background, training and proficiency; the examinations requested by police investigators and their purpose; chain of custody information for exhibits; description of the tests conducted, materials used and procedures of both biological examination and DNA profiling; the peer review of methods used; limitations of these methods and their relevance to the forensic evidence of the case; the expertise testing of scientists and validation testing of methods; the similarities and dissimilarities of the DNA profiles compared; alternative explanations for results, where relevant, and reasons for their rejection; information on the population databases used and discussion of the conclusions and implications of analyses. Information about the limitations and assumptions involved in the discipline might be particularly beneficial as these would dissuade readers from believing that scientific evidence is certain. While the list is long, brief information could be included in the reporting template; it would not be necessary to write afresh for each report [34].

practitioners and jurors. The example (see 4.4) of a prosecutor’s question about the statistic and associated inference highlights the challenges that legal practitioners face in regard to statistical reasoning and may also reflect a belief that forensic science can prove who committed a crime, without any potential for error or uncertainty [3]. In line with previous recommendations [8], this study found that counsel did ask more questions about complex elements of forensic science, such as to elicit explanations of likelihood ratios. This study highlighted, as might be expected, that prosecutors prompted discussion of the main elements of expert evidence that required explanation. The role of defence has been highlighted in presenting a balanced view of expert evidence [8,22]. Accordingly, this study highlights that defence introduced questions on elements that had not been raised by the prosecution. It may be that defence counsel are gaining increased familiarity with the types of questions to ask [23]. Additionally, judges sought further clarification from the scientist on some occasions and scientists provided further explanation about some elements. These findings provide empirical support from major cases for research suggesting that experts and legal practitioners share responsibility in presenting expert evidence to the jury [8]. 5.3. Implications for practice and research As has been recommended elsewhere [32,34], ideally, expert reports should include all information that is necessary to explain the key elements of the forensic process. This is important because only a small proportion of cases proceed to trial [45], and of these, expert testimony is not presented in every case. More detailed explanations may be helpful to practitioners who use them in their decision-making, such as police in investigations, lawyers in pre-trial preparation, and judges in court. When a case does go to trial, pre-trial meetings may assist lawyers and forensic scientists to ensure that they can best cover all information in their co-presentation of expert evidence to the jury [8]. It may be that in the cases examined in this study such meetings had occurred, as they are more typical in serious cases. Future research should investigate the views of forensic scientists and other practitioners about the adequacy of report content and the experiences of those in jurisdictions in which major reporting revisions have been implemented. Although expert testimony filled the gaps of expert reports, it could be further enhanced. In some cases, further explanation of the hypotheses used and more elaboration about likelihood ratios may be beneficial. The complexity of expressions of the weight of evidence can unduly influence and confuse jurors about the extent to which facts of a case can be substantiated by the science [7,12]. The findings of the current study showed that the term ‘match’ was used within expert testimony, sometimes without clarification that a match refers to the 21-loci profile compared. This term is reportedly no longer used in FSST’s reports now that likelihood ratios are reported; however, it is an area for consideration by forensic scientists elsewhere. Further research could explore various presentation formats in more detail to build on past research. The expert testimony in one case of the sample in this study featured a PowerPoint presentation. Such presentations have been shown to increase mock juror understanding of these topics [46]. They allow for the comprehensive and well-sequenced presentation of background information to provide a basis for jurors to understand the case-specific evidence to follow. Further research could establish the prevalence of this approach, forensic scientists’ and legal practitioners’ rationales for adopting it, and jurors’ perceptions of its use in cases. This study also identified cases in which extracts of expert reports were provided to the jury. Research could explore this practice in detail to determine whether this helps or hinders juror understanding of forensic evidence. Further research should also replicate the current study with different forensic disciplines, to support the transferability of findings of the current research to various forms of forensic expertise. Research in jurisdictions that have

5.2. Expert testimony As might be expected, the specific content included in expert testimony was found to vary from case to case according to the complexity of cases, the forensic analysis undertaken, the position taken by defence, and the expert report provided. The findings of this study indicate that much of the information recommended for inclusion was discussed within expert testimony. On the whole, forensic scientists seemed to have had ample opportunity in court to provide explanations of their scientific opinions and the results of their analyses. This conclusion is based on the presence of essential information of forensic analyses that was observed within expert testimony, as well as forensic scientists’ ability to provide further explanation due to legal counsel’s use of open questions. Indeed, information provision on certain aspects of the forensic science was consistently present across cases. In particular, explanations of the foundational basics of DNA and BPA, analytical procedures, and questioning by counsel adhered closely to recommendations in most cases. Further, this study highlighted the efforts made in practice by scientists and lawyers to bypass inherent barriers and assist jurors to understand the evidence that they must evaluate. These included the use of a PowerPoint presentation and provision of extracts of expert reports to the jury. Previous research into the experiences of communication between forensic scientists and legal practitioners reported that Supreme Court judges and legal practitioners found it helpful when forensic scientists started with the basics and explained each step of their analysis process in a clear and logical sequence [8]. Forensic biologists’ concern that counsel could make scientific evidence look inappropriately strong or weak necessitates the inclusion of clearly explained measures of uncertainty [8]. The results of the current study allay this concern somewhat. In the cases examined (as outlined in Section 4.4), as counsel advanced their arguments forensic scientists were able to include sources of uncertainty in the results discussed. Additionally, all cases included an explanation of the statistics used, suggesting an effort to assist laypeople to understand the uncertainty associated with findings. However, as highlighted by research [39], it is a challenge to prevent misunderstandings of statistical expressions amongst legal 10

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developed more detailed expert reports would be valuable to assess the impacts on testimony before and after such developments. Given a lack of consensus amongst forensic scientists [42], it would be worthwhile to investigate forensic scientists’ and other criminal justice practitioners’ perceptions of the right balance of information in reports and testimony. Greater understanding of these perceptions may help to explain further what happens in practice.

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5.4. Limitations A limitation of content analysis is its reliance on written texts; it was not possible to incorporate non-verbal cues, such as pauses and gestures, which may also impact understanding. The sample size of 10 finalised cases does not lend itself to generalisation of results; however, it allowed an in-depth examination of the communication in these cases and provides a basis for comparison with other disciplines and jurisdictions. Although the testimony in our sample included many of the reporting elements recommended in previous research, it is not known whether the forensic scientists who testified as experts in these cases perceived that they had adequate opportunity to explain their evidence. Similarly, it is not known whether pre-trial meetings were held, nor whether the jurors understood what was presented. 6. Conclusion This study explored the presentation of forensic biological expert reports and corresponding testimony in major crimes against the person. While expert reports were brief and omitted much of the detail recommended to allow the reader a greater understanding of the evidence, testimony provided opportunities for forensic scientists to elaborate on their findings and expert opinion. The study found that the practices of experts and legal practitioners in providing expert testimony are mostly in line with relevant recommendations. Generally, prosecutors elicited key information from forensic scientists, and when they did not, additional information was introduced by expert witnesses themselves or by defence in cross-examination. Overall, therefore, forensic scientists were able to elaborate on their findings and opinions in court in these major cases. This study provides empirical research on expert reports and testimony to contribute to well-informed decision making by jurors in major cases that involve expert evidence. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements We thank the Supreme Court of Tasmania, the Tasmanian Department of Police, Fire and Emergency Management (DPFEM), and Forensic Science Service Tasmania (FSST) for their support of this project. Thanks also to the Forensic Biology Section at FSST for providing and de-identifying the data for the study and for providing helpful comments on an earlier draft. The views expressed in the paper do not necessarily reflect those of the participating organisations. Funding sources This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. References [1] H.F. Fradella, S.S. Owen, T.W. Burke, Building bridges between criminal justice and the forensic sciences to create forensic studies programs, J. Crim. Justice Educ. 18

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