The following article, applicable to experts in all areas of expertise, was written by me in conjunction with my Courtroom Testimony for Expert Witnesses course and will soon be published in the Canadian Society of Forensic Science Journal. It will be available on an Open Access basis and once published, it will be available at http://dx.doi.org/10.1080/00085030.2022.2135742
Below is the text of this article.
Abstract
The search for the truth can be a daunting task, but without knowing what happened and who is responsible, there can be no attempt at achieving any measure of justice. Forensic scientists often play a pivotal role in determining significant facts and interpreting those facts for the court to consider. When called to testify, expert witnesses have a special duty to the court to provide fair, objective, and non-partisan assistance. The courtroom becomes the classroom as the expert witness takes on pedagogical duties of teaching the underlying science, methodology, and the nuances of forensic opinions. Depending on the area of expertise and evidence, the learning curve for the trier of fact can be steep. The didactic presentation of complex data requires planning and skill. Drawing upon my Courtroom Testimony for Expert Witnesses course and my PhD research, I focus on the search for truth, expert witness bias, and the challenge of teaching complex science to the trier of fact. There will be specific emphasis on the incorporation of visual evidence to explain complex concepts in a more concise and memorable manner to aid in comprehension. The expert witness is a teacher and how the expert teaches makes a difference.
Keywords: Truth; expert witness bias; pedagogical; visual evidence; didactic presentation
Introduction
The search for the truth is the foundation of a criminal prosecution because it is only after we know the truth that questions of criminal liability and punishment can be answered. Though it may appear that once we know the facts, we will know the truth, experience does not bear this out. Facts do not always equate with truth. A direct link between facts and truth may prove illusive as facts can be malleable and may give rise to competing explanations, perspectives, theories, and realities. The presence of DNA, a fingerprint, or other trace evidence in a specific location is a fact but does not necessarily lead to the truth as to how it got there and under what circumstances. The complete truth may be illusory due to missing, prevaricating or imperfect witnesses, equivocal evidence, the absence of evidence, facts that legitimately give rise to multiple interpretations, or vast chasms of the unknown between known facts. The parties must strive to get as near to the complete truth as possible.
It would be optimistic to rely upon the trial process to conclusively determine the truth, yet despite what is often a rather challenging quest, replete with roadblocks, rabbit holes, and diversions, the goal must be to seek the truth. Without knowing what happened and who is responsible, there can be no attempt at achieving justice, however illusive that goal may be. While truth does not guarantee justice, it is an essential precondition for it. It follows that selecting, leading, and challenging evidence should be aimed at ascertaining truth. Truth is not just an esoteric academic precept – the goal of ascertaining the truth is well established in domestic courts and international criminal tribunals and courts. The Supreme Court of Canada, in R. v. Nikolovski [1], said that, “The ultimate aim of any trial, criminal or civil, must be to seek and to ascertain the truth.” Defendants are not always keen on the truth coming out as the truth may not set them free. Nor are police and prosecutors always keen on the truth as it may get in the way of their conception of the case. The many wrongful conviction cases in Canada, the United States, and elsewhere bear this comment out.
Rationally, armed with the facts, the court should be able to divine the truth. It may be convoluted and difficult to ascertain, but there should ultimately be one truth. Not a prosecution truth, nor a defence truth, but the truth. Honest justice, not just the façade of justice. I caution that truth may not be a solitary construct. There may be multiple truths about an event or at least layers of truth. Note the cautionary admonition of the Israel Supreme Court in acquitting Ivan Demjanjuk of the allegation that he was “Ivan the Terrible”, an operator of the gas chambers at Treblinka, “The matter is closed – but not complete. The complete truth is not the prerogative of the human judge.” [2]
Determining the truth is not a utopian construct. It is the very essence of forensic science, even though evidence is sometimes open to interpretation. There may be disputes as to what the facts are because the data are equivocal. Data may give rise to legitimate differences in interpretation of what it means. A more experienced expert may see things differently than a less experienced expert. There may also be legitimate scientific debate regarding the validity of forensic interpretations as seen in bitemark analysis, ear print identification, etc. [3] Forensic science has fluidity. Forensic scientists determine facts and, in some cases, interpret what those facts mean. When testifying, they become teachers, and how they teach makes a difference. This paper focuses on the pedagogical expert and the importance of teaching complex science in the courtroom.
To Whom Does an Expert Witness Owe a Duty?
To contextualize the pedagogical role of the expert witness, it is important to understand the fundamental duty of an expert witness. Is the goal to please the party that retained the expert? Should the expert resist being helpful to the opposing party? This question of duty is inextricably linked with bias, defined as an inclination or prejudice for or against one person or group, especially in a way considered to be unfair [4, 5]. Expert witness bias has been a longstanding concern among counsel and the courts in criminal and civil cases. An expert witness’s lack of independence and impartiality can result in egregious miscarriages of justice. There are many examples of experts being unfairly favorable to one side or the other in litigation. This bias is sometimes intentional – wanting to support the “team” – and sometimes subconscious, but present nevertheless.
In 2015, the Supreme Court of Canada issued a major ruling on the issue of expert witness bias. In White Burgess Langille Inman v. Abbott and Haliburton Co. [6], the Court stated:
Expert witnesses have a special duty to the court to provide fair, objective and non-partisan assistance. A proposed expert witness who is unable or unwilling to comply with this duty is not qualified to give expert opinion evidence and should not be permitted to do so… (para. 2)
Significantly, the Court stated that a proposed expert’s independence and impartiality goes to admissibility, not just weight. The Court focused on three related concepts. First, impartiality – the opinion must reflect an objective assessment of the questions posed. Second, independence – the opinion must be the product of the expert’s independent judgment, uninfluenced by the party that has retained the expert or the outcome of the litigation. Third, absence of bias – the opinion must not unfairly favor one party’s position over another. The acid test is whether the expert’s opinion would vary depending on which party retained the expert. The fact that experts work for the state or are privately retained, instructed, and paid by one party in the litigation does not alone undermine the expert’s independence, impartiality, and freedom from bias. Irrespective of the instructing party, the expert must be fair, objective, and non-partisan. The expert must be aware of this primary duty to the court and be able and willing to carry it out.
Perspective is important. The expert is not a prosecution expert or a prosecution witness. Nor is the expert a defence expert or a defence witness. Thinking in those terms sows the seeds for becoming a biased witness. Rather, the expert is an expert being called by the prosecution or by the defence. This subtle but important shift in perspective will help solidify in the expert’s mind to whom a duty is owed.
Bias can affect how experts think and work. There are two kinds of bias. Motivational bias involves a conscious decision to please a certain party or reach a certain result [7, 8]. This type of bias can often be ferreted out by effective cross examination. More pernicious is cognitive bias, which is unconscious or unintended bias, and may be harder to identify [9]. Bias can be identified and mitigated but it cannot be wholly eliminated. Experts must recognize how bias can affect their work and take steps to mitigate it. Expert witnesses must be aware of their primary duty to the court and must be able and willing to carry out that duty.
Teaching Complex Science in the Courtroom
All prosecutions fundamentally involve pedagogy as counsel teach the court about the prosecution theory and the evidence relied upon to support it. The same applies to the forensic science component of a case. Experts and counsel must consider how to present the forensic evidence in the most effective manner, mindful that the learning curve for the trier of fact may be rather steep. While entertainment value is not the goal, so too must tedium be avoided. Words will be required, but at times words cannot adequately convey the true meaning of the evidence. It is in these darker corners where visual evidence can serve a didactic purpose, casting much needed light. The balance of this paper focuses on the use of visual evidence to convey complex concepts and evidence.
While judges may take judicial notice of facts of common knowledge, adjudicated facts, and documentary evidence, they are not entitled to take judicial notice of complex scientific principles and methodologies. They must gain that knowledge within the confines of the trial and the evidence tendered by the parties. The onus therefore falls upon counsel and expert witnesses to educate the court. This takes on even greater importance when a jury is involved as they too must make findings of fact based only on the evidence presented. The jury must be educated in the courtroom to avoid the impact of the CSI Effect, whereby jurors decide cases based on popularized depictions of forensic science in the entertainment industry, irrespective of whether those portrayals are correct. Since counsel only gets one opportunity to convey their evidence to the court, it is essential that the presentation be didactically effective. It must appear to observers and participants alike to be seamless, surgical, informative, and efficient.
Research in education and psychology has shown that different presentation mediums can have differing impacts on an audience [10, 11, 12, 13]. Our brains are wired to process visual information, such as images, very differently than text and sound. In multimodal learning, visual images are processed in several channels instead of one, giving the brain a far deeper and more meaningful encoding experience. Visual evidence is comprehended differently than words, with visual information being digested more quickly and globally along with a heightened, though not necessarily justified, sense of understanding [14, 15]. It is also remembered better than words. Data visualization, the process of using art, creativity, and math to visually present large amounts of data, can help to explain complex concepts more concisely and memorably [16]. The more complex the material, the more visual evidence can aid in comprehension. Even mathematical data can be more effectively conveyed and understood when presented in graphical form rather than just numbers and equations. How information is presented, interpreted, and understood is dependent upon what information has been selected, to whom it is being shown, and the purposes for showing it. Forensic experts and counsel must therefore consider how to weave visual evidence into the trial narrative in a manner that makes the telling of the story more complete, more impactful, and that does justice to the evidence.
Effective multimedia presentations convey complexity with greater efficiency than words alone and may assist counsel and experts to convey scientific, technical, or abstract information to the court. When presenting complex scientific evidence, there is merit in beginning with an introductory visual presentation designed to teach the court about the science generally, before focusing on specific case facts. A viewer who invests time and effort to interpret and understand complex visual evidence may believe more strongly in their interpretation because of the effort expended. Truth discovered is more powerful than truth told.
Criminal prosecutions often involve complex scientific evidence that must be presented in such a way as to educate the court to ensure full comprehension and an understanding of the probative value of the evidence. Visual depiction is an essential component of that pedagogic exercise. An expert witness who teaches complex material effectively can induce that lightbulb moment when the knowledge level of the viewer is improved. When images are only semi-legible, additional interpretive work and expert assistance are required to understand their meaning. DNA profiles, x-rays, CT scans, fingerprints, and fMRI imagery are examples of semi-legible displays that can only be understood with expert interpretation [17].
Depending upon the evidence to be presented, the following methods of visual presentation may be effective. Due to space limitations, these are summaries only.
a) Photographs and Video
There is often strategic value in using photographic or video images to supplement testimony and other forms of evidence. Counsel must consider whether single or moving image format will be more effective in conveying visual information when both formats are available. In part, this choice is dependent upon the information sought to be conveyed as some information is better presented by way of still images, particularly when detailed image content is critical. Conversely, moving images often engender greater viewer comprehension as they provide certain communicative efficiencies over still images. To maximize the epistemic value of the images, they should be presented electronically via a computer monitor or HD presentation screen rather than via LCD projector (bad) or hard copy (worse) as visual detail is lost using these latter methods.
b) Maps
Maps are quite effective for depicting the overall layout of a city or the geography of rural locations as well as the details of specific events. Whether produced by government, commercial entity or investigators, maps can provide a clinical view that has didactic value, teaching the court about locations of interest in a manner that is familiar and readily understandable. They allow the court to locate areas of interest and gain an appreciation of distances involved. Two-dimensional digital depictions of smaller areas can be created by easy-to-use freeware drafting tools and more complex tools like Photoshop™ or Revit™.
c) Diagrams and Charts
Presenting compendious data visually can be an effective method of collating evidence from diverse sources. Often the most effective way to explain complex relationship, event, and location data is pictorially. Diagrams and flowcharts are proven methods for presenting, understanding, and retaining complex information. Platforms such as Microsoft Visio™, MindMeister™, IBM i2 Analyze™, and others are very effective visual presentation tools that permit the collaborative flowcharting of relationship data.
d) Three-Dimensional Models and Terrestrial Laser Scanning
Accurate and detailed depictions of crime scenes, areas of interest, and objects provide investigators, counsel, and the court with data necessary to comprehend available evidence more fulsomely [18]. Scene measurements, including the location of objects and features within a scene, are central to a proper scene reconstruction, especially given that scenes are transient and that what may seem unimportant at the outset could take on great significance at trial [19]. Terrestrial laser scanning can be used to incorporate data points to create 3D models and scenes in a digital visually appealing form. Computer based 3D modelling is particularly helpful when vertical dimensions of geographic, scene-based, or other features are important. 3D modelling can be effective in adding clarity to expert testimony and in increasing viewer comprehension.
e) Computer Generated Visualizations
Computer generated visualizations produce an image, diagram, graphic, or animation that represents underlying data and are designed to aid in the visual comprehension of the data by depicting what happened in a specific event or what is believed to have happened [20]. They are particularly helpful when an event is difficult to otherwise visualize, cannot be physically reproduced, is technically complex, when facts are disputed, and when timing is critical to evaluating the event [21]. These visualizations can represent with clarity and precision factual details and variations thereof that might be very difficult to imagine relying upon verbal descriptions alone. They can improve the viewer’s ability to comprehend dynamic events, especially when supplemented with oral narration [13]. They may take the form of animations or simulations. Caution is required when utilizing computer generated visualizations as they must fairly and accurately represent the evidence they purport to explain.
Conclusion
Experts not only conduct forensic analysis; they also teach the court how to soundly incorporate it when deciding the facts of a case. There is a spectrum of expert evidence presentation in the courtroom, ranging from clinical and rather uninteresting to dynamic, visual, and didactic. Experts should strive towards the advanced end of the spectrum to fully deliver on their duty to the court. Turn the courtroom into a classroom. This can be done subtly and incrementally so that at first counsel and court may not realize they are being taught. You can be the pedagogical expert witness, teaching complex science in the courtroom.
References
[1] R. v. Nikolovski (1996), 111 C.C.C. (3d) 403, at 409.
[2] Demjanjuk v. Israel, Crim. App. No. 347/88, at 41.
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[6] White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23.
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