a 3D printer printing a hand

3D Exhibits May Help Jurors Understand an Expert’s Technical Testimony

Written on Wednesday, September 15th, 2021 by T.C. Kelly
Filed under: Research & Trends

Lawyers depend upon expert witnesses to convey their opinions in clear language, breaking down complex ideas into digestible portions that juries and judges can comprehend. While words are an expert witness’ primary tool, juries understand evidence more readily when they can visualize a concept.

Studies suggest that people are more likely to understand new information when it is presented both in narrative and visual form.  Brains process information more effectively when they are stimulated simultaneously though multiple senses, including hearing and seeing.

Demonstrative Evidence

An expert’s visual evidence may be real or demonstrative. Real evidence (also known as physical or evidence) is an object that is material to the litigation. A dented fender with a paint transfer or a fragment of a device that exploded are examples of real evidence. Experts exhibit real evidence to juries while explaining how an examination or study of the evidence caused the expert to form particular opinions.

Demonstrative evidence is a representation of real evidence. Demonstrative evidence depicts a scene, object, or condition as it actually existed. Photographs of an accident scene or an x-ray of a broken bone are examples of demonstrative evidence. Experts use those exhibits to assist their narration of opinions just as they would use real evidence.

Expert witnesses have historically prepared diagrams or drawings to illustrate their testimony. A spinal surgeon might draw a picture of vertebrae to illustrate where an injury occurred, while an accident reconstruction engineer might use a diagram to pinpoint the location of skid marks or debris at an accident scene. 

Because they are familiar to lawyers and courts, diagrams and drawings are usually uncontroversial. The expert will testify that the exhibit accurately depicts the thing it represents and, while the opposing party is free to challenge that testimony on cross-examination, the jury will usually be allowed to see the exhibit if the expert affirms that is a reasonably accurate representation of the facts and if the court finds that it is not misleading or otherwise prejudicial.

Visualization Evidence

Some demonstrative evidence is intended to allow juries to visualize events described by eyewitnesses or deduced by experts. An animation that demonstrates how an accident occurred (or how an expert believes it must have occurred) allows a jury to visualize the accident rather than relying solely on an explanation of a diagram.

As technology has become more sophisticated, so has demonstrative evidence. Three-dimensional visualizations — commonly used by architects to allow a virtual “walk through” of a planned home — allow experts to change the viewer’s perspective so that a scene can be observed from different angles or perspectives. The explosion of 3D printer technology allows experts to build models of objects to exacting specifications.

Like most people, judges tend to resist change. Judges were once wary of technology creeping into the courtroom. Each new generation of judges, however, has been more accepting of technology that has become commonplace. While judges were once skeptical about animations, most judges now allow experts to illustrate their opinions with animated evidence if the expert authenticates the animation by testifying that it fairly and accurately represents the expert’s conclusions.

3D Evidence and Verdicts

While there is evidence that demonstrative evidence helps juries understand complex testimony, it is less clear whether 3D visualizations are more helpful to juries than photographs as jurors attempt to understand an expert’s testimony. A forensic scientist, a psychologist, and two colleagues designed an experiment to determine the impact that different kinds of visual evidence have on juries.

The authors conducted mock trials before randomly selected individuals who played the role of jurors. They presented evidence to different jurors using three kinds of demonstrative evidence. Testimony established that two men left a tavern together. One of the men fell and died after suffering a serious skull fracture. The question for the jury was whether the victim fell accidentally or was pushed.

A forensic anthropologist testified as an expert witness for the prosecution. The juries heard the same recorded testimony in each trial. The expert used technical language to explain the damage to the victim’s skull.

The experimenters varied the nature of the visual evidence that was shown to the jury as the expert testified. In one set of trials, the jurors saw a photograph of the victim’s skull. In a second set of trials, the jurors viewed a 3D visualization of the same skull. In the third set of trials, the jurors considered a 3D printed model of the skull. The skull was circulated among the jurors, allowing them to touch and examine the exhibit, during the expert’s testimony.

The jurors did not deliberate. Instead, each juror completed questionnaires at the end of the trial. About three-fourths of the jurors who viewed the photograph or the 3D visualization would have returned a “not guilty” verdict, while only 55% of jurors who saw the 3D printed model would have acquitted.

The experimenters were cautious about attributing significance to the trial outcome as the experiment was not designed to test whether (as other studies have suggested) demonstrative evidence may induce a pro-prosecution outcome in criminal trials. The experimenters did note that jurors who handled the 3D printed model were more likely to conclude that the amount of force required to damage the skull was indicative of guilt. 

Since the expert gave no testimony about the amount of force needed to cause skull trauma, the experimenters suggested that caution should be exercised in allowing jurors to handle 3D printed models of evidence. Perhaps the handling of a skull evoked an emotional response that made jurors more likely to view a defendant as guilty. 

3D Evidence and Comprehension

The experimenters asked whether jurors understood the visual evidence and how the visual evidence helped jurors understand the expert’s testimony. About three-quarters of the jurors found the exhibit itself to be comprehensible, regardless of its nature, although jurors were slightly more likely to understand the 3D printed model.

More importantly, the experimenters found that 79% of jurors who viewed the photograph thought they understood the expert’s technical language. The use of 3D technology improved the jurors’ understanding of the expert’s jargon. When jurors viewed a 3D visualization of the skull, 88% of jurors thought they understood the expert’s language. When jurors viewed the 3D printed model, 94% of jurors said they understood the expert’s technical testimony.

The experimenters suggested that the study might offer evidence that jurors are less likely to misinterpret an expert’s testimony when the experts use 3D reconstructions to explain the terms that they use. The study might also suggest that jurors place greater weight on conclusions they draw from 3D exhibits than they place on conclusions drawn from the expert’s testimony. 

On the whole, the study offered some evidence that 3D exhibits help jurors understand an expert’s technical language. Lawyers may wish to consider 3D exhibits as an alternative to photographic evidence or diagrams if experts feel comfortable using those exhibits to explain their opinions.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.

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