Admissibility of Computer-Generated Evidence: A Case Study of People v. Duenas

“When an animation is done properly, it can show in a few seconds what no amount of oral expert testimony can get across.” - Morgan C. Smith
Photo by Sigmund on Unsplash

Due to the rapid changes in technology, attorneys now have the means to create photo-realistic animations on any subject imaginable for their cases. Attorneys now work with expert motion and graphics companies and agencies to create animations for different subjects relating to their cases including medical, architectural, engineering, etc. In an article published by the American Bar Association, it is said that “computer-generated evidence has become more and more common in today’s courtrooms, and nearly every state and federal circuit has addressed its use”. However, with its increased use, attorneys during various cases have considered its admissibility at trial. A good example is the case of People vs Duenas

In this case, The Supreme Court of California affirmed a judgment of conviction for the first-degree murder of a sheriff’s deputy and sentence of death. Defendant contends that the trial court abused its discretion in admitting the animation. He argues that the animation reflects speculation about key aspects of the shooting of Deputy Hoenig, gave the prosecution‘s case a gratuitous ambiance of scientific validity, and was cumulative of other evidence. Defendant contends that the animation is speculative regarding two aspects of the shooting which are the locations from which he fired the shots and the sequence in which he did so. 

Computer-Generated Evidence
Seal of the Supreme Court of California

This claim was as a result of the animation being mostly still images that began with an image of the street where Deputy Hoenig was shot by the defendant; showing how his patrol car parked to the right and slightly obstructing a driveway. The viewer’s perspective depicted in the animation then shifted to the driver’s side of the patrol car. From that perspective, a fallen bicycle and a standing figure were visible on the sidewalk beyond the patrol car.

The viewer’s perspective continued to shift as the first gunshot was fired, showing the impacts of the bullet on the rear window of the patrol car and on Deputy Hoenig’s hand. The viewer’s perspective then continued to shift as the shooter was shown moving around the car, firing three more shots at the fallen deputy, and fleeing while still firing more shots.

During the trial, over Duenas’ objection, the prosecution‘s expert witnesses Dr. Carley Ward (a biomechanics expert), and Parris Ward (a graphics expert) explained that prior to trial, the animation was created based on both police and autopsy reports, and the evidence, including shell casings, recovered from the crime scene. 

Dr. Ward presented her opinions as to how the shooting happened using the created animation to illustrate her testimony. Prior to the animation being played, Parris Ward informed the jury that animation “doesn’t tell you, because it’s from a computer, that this had to happen this way.” Instead, he explained, it was “an illustrative tool for explaining concepts.” The trial court also gave the jury a cautionary instruction explaining that the animation they were about to see is based on a compilation of different expert opinions.

The Supreme Court of California affirmed the judgment convicting the defendant and sentencing him to death, holding that the trial court duly admitted the computer-generated animation used by the prosecutor. It maintained that the ample cautionary instructions as touching the limited use of a computer-generated animation routed the defendant’s claim that the trial court abused its discretion in admitting the animation as to how the said shooting occurred. Besides, what was illustrated in the animation was expert opinion formed based on substantive evidence gathered at the crime scene as well as autopsy reports.


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