Part of being an expert witness—perhaps the most important part—is ensuring the jury understands the evidence presented. If an expert gets on the stand and spews technical, discipline-specific jargon, odds are the jury is going to become not only confused but also irritated. Those emotions can have a negative impact on the case, and justice.
This problem is only exacerbated in regard to skeletal trauma, as bringing a human skull into court is usually frowned upon. To compensate, lawyers and experts have used 2D photographs in the past, as well as 3D imaging, virtual environments and simulations more recently. Now, a team of researchers from the Cranfield Forensic Institute (UK) have tested another successful option—3D printing.
In a study, published in the International Journal of Legal Medicine, the researchers found that 94 percent of jurors understood the technical language of an expert when presented with a 3D-printed model of skull trauma. However, the 3D-printed model did not have a significant influence over verdict when compared with photographs and 3D visualizations.
For the study, 91 individuals were randomly assigned 2D photographs, 3D visualizations or a 3D-printed model as visual evidence in a mock courtroom experience. The “trial” involved two adult males leaving a bar. On their way home, one of the individuals survived a fall that resulted in a severe head injury associated with a cranial fracture. The jurors had to determine whether the victim fell or was pushed by the defendant.
A forensic anthropologist served as an expert witness, and his/her audio recording was played to jurors assigned one of the three imaging techniques for visualization. The photographic evidence and 3D model were displayed real-time to the jurors in the form of a video demonstration, and they matched up to the particular area the forensic pathologist was discussing. Meanwhile, the 3D-printed model was physically demonstrated to the jury as an object that could be passed between them.
Through a questionnaire completed by the jurors, the researchers determined there was no correlation between the type of evidence presented and the overall verdict. And while there was no statistical significance, the study results indicated jurors’ understanding of technical language increased with the use of 3D visualizations.
For example, 79 percent of jurors who looked at photographic images said they understood the technical language of the forensic anthropologist witness. However, 88 percent of jurors who looked at 3D simulations said they understood and 94 percent of jurors who viewed the 3D-printed model stated they understood the technical language.
“The results demonstrate that visually, the clearer the jurors find the evidence and information depicted in the courtroom, the easier it is to understand the technical language used by the expert witness,” the authors wrote. “However, the outcome is not quite that straightforward. In cases where the evidence is deemed clear by the jurors, then comprehension of technical language shows statistical significance. This suggests that the overriding influence on the juror is the evidence type itself as opposed to the language associated with it.”
Therefore, at this time, the researchers recommend the use of 3D imaging since, if this is used for all evidence types, greater technical understanding is likely to be achieved.