Accident Reconstruction ExpertsIntroduction:

In the December 2015 Verbatim short, “Expert Witness,” director Brett Weiner makes an important point about expert witnesses in the context of accident reconstruction litigation.  “Verbartim” short films use actual courtroom transcripts to make certain arguements.  See Brett Weiner, “Verbatim: Expert Witness,” The New York Times, (2015)[1]; This article addresses accident reconstruction cases and the issue of expert witnesses who over-rely on technology thereby creating problems with evidence that can have serious consequences.


In Weiner’s “Expert Witness” article that accompanies the film, the expert who was deposed refused to answer questions that involved a basic mathematical formula and that would have allowed opposing counsel to understand how much actual distance was represented by a diagram drawn to scale. See Weiner-film, supra.  The equation the expert is asked to perform is one that can be done using a calculator and that, according to evidence provided in a motion on the matter, would only require the mathematical skills of an average eighth-grade student. See id. The point that Weiner makes is that while the expert in the case was able to generate a diagram and a conclusion (although the distance provided by the witness was erroneous by some four feet), he could not explain how he reached that conclusion or what his methodology was. See id.; See also Weiner-article, supra. Weiner explains: “The ‘expert witness’ in this case would not answer questions without his ‘formula sheets,’ which were computer models used to reconstruct accidents. When asked to back up his work with basic calculations, he deflected, repeatedly derailing the proceedings… . [This] is a warning for experts who rely heavily on technology. When it comes to expertise, knowing how to plug numbers into software is not a substitute for understanding the subject matter.” Id.

The point Weiner makes is an important one: that expert witnesses should not rely on technology to do the work (or the explaining) for them, that experts themselves must understand the underlying substantive issues, and that technology is not, in itself, an “expert.”

Others have made similar observations in the context of accident reconstruction litigation, even going a step further and arguing that sometimes, the technology used in accident litigation can impede efforts to get at the truth of what took place. See, e.g., Damian Schofield, “Seeing is Believing: Graphical Evidence and its Effect on the Viewer,” Evidence Technology Magazine, June 2012. One computer analyst and expert witness has highlighted a very serious issue. Dr. Damian Schofield argues that visual tools, such as computer animations that are used to reconstruct accidents, are among the most powerful and persuasive tools to jurors. See id. Because of the power of these tools, extraordinary caution is needed, and experts must not only be able to explain technology-based evidence to jurors, but must also take care to ensure that the images being depicted are reliable, authentic, and accurate. See id.

Schofield’s concern is a valid one. He explains that “Moving images tend to mesmerize, and they can relax an individual’s critical nature. This means that viewers are inclined toward a “seeing is believing” attitude,. . .potentially reducing the standards expected of the evidence. Small alterations to a digital representation of an incident can have a substantial effect on the impression it gives. For example, judgments of speed and recklessness are critical in determining responsibility for road accidents. A driver traveling at speed may seem to be reckless if the reconstruction includes young children near the road, but reasonable if adults are represented. Hence, apparently innocuous decisions about virtual object representation are often critical.” Id.

Furthermore, Schofield points out that because of the overwhelmingly persuasive power of the computer-animated exhibits that are commonly used in accident reconstruction cases, it is incumbent upon attorneys, expert witnesses, and judges to carefully scrutinize these types of evidence. See id. Evidence is generally admissible if its value as proof outweighs the prejudicial effect it may have upon jurors, and Schofield cautions that with computer-animated media, this can be a real issue. Id. For example, a visual demonstration can captivate jurors and persuade them, even if it is rife with inaccuracies. See id. According to Schofield, “a juror’s memory retention improves drastically when comparing visual evidence to oral testimony. Experiments…have shown that when the claimant and defense used an animation to depict their own partisan theories, participants increasingly made judgments that contradicted the physical evidence… .[C]omputer-animated displays can have a greater effect than oral testimony. The memory of a witness to an event can also be biased by computer-generated visual evidence.” Id.

Schofield highlights three serious concerns with over-reliance on computer-animated technology and similar tools: (1). It can be manipulated by attorneys and experts to such an extent that it tells a false story, but that story is accepted as true by jurors because of the incredibly persuasive nature of such evidence; (2). It can affect how actual witnesses testify, in that such witnesses may not remember certain events accurately after viewing computer-generated exhibits; and (3). It is difficult, despite various evidentiary rules, for a judge to know when evidence of this kind is manipulated in a way that undermines the accuracy of the narrative, so it is harder to safeguard against the introduction of misleading technological evidence. See id.

Both Weiner and Schofield make important points about using technology in accident reconstruction cases. Weiner’s analysis underlines the need for expert witnesses to be able to explain how they arrived at certain conclusions, rather than simply depending on technology to do that work for them. An expert witness should not only know how to plug in numbers, but should truly comprehend the substantive issues and be able to convey clearly that understanding to a jury. As one police officer, who frequently uses and observes technological tools in accidents argues, “[T]echonolgy sometimes must take a backseat to common sense. The real ‘software’ resides between our ears; the real ‘firmware’ resides between our solar-plexus and our spine,” and “Overdependence [on technology] can hamper the progress of a critical incident investigation…”. John Rivera, “Tampering our over-reliance on technology,”  (May 12, 2012). Expert witnesses should possess the ability to explain an exhibit or occurrence accurately and clearly, without depending so much on technology that they lose sight of the function of expert testimony—to assist the jury in determining what actually occurred, how it occurred, and what decision should be rendered.

Similarly, Schofield’s analysis underscores the importance of having experts and attorneys who use visual exhibits in court take extraordinary and cautious steps to ensure that such exhibits are accurate and that they do not contradict physical evidence or other testimony. Because such exhibits are so persuasive to jurors, there is a greater risk that jurors will be misled, ignore contradictory physical evidence, and fail to critically analyze computer-generated evidence. See Schofield, supra. Proponents of such evidence must ensure that it is factually correct in every respect, from lighting to distance. See id.  Schofield points out the need for accident reconstruction analysts to exert caution in relying on such tools as a substitute for an actual expert opinion. See id.


Technology and computer-generated exhibits can, if consistent with the truth, be of great value in accident litigation. Their persuasive value is unquestionable. However, when trying cases of this sort, attorneys should take great care to ensure that their expert witnesses are the true experts in the matter, and that technological tools are used only to supplement an accurate narrative, not to supplant it. In turn, good experts will be able to explain the rationale and logic behind their conclusions, and they, too, will utilize technology in an effort to assist in making the facts clear, rather than relying on the technology itself to act as the “expert witness.”

[1]    To distinguish between the film and the article (which bear the same name) in citations, the film will be cited as “Weiner-film,” while the article will be cited as “Weiner-article.” Where the two are listed together in a citation, the “id.” notation will be used to refer the second source, whereas “supra” will be used to denote the first source.