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Using Computer-Generated Animation and Simulation Evidence at Trial: What You Should Know

The use of computer-generated animations and simulations is on the rise in courtrooms around the country, and for good reason – animations and simulations can greatly increase jurors’ understanding of complex issues, and are of extraordinary help in products liability cases in particular. However, animation and simulation evidence can also be a distraction to jurors, can carry more influence than it should, and can distort the facts of a case. In short, this emerging form of evidence is a powerful persuasive tool.

Courts are aware of the influence of these new evidentiary devices, and have begun establishing guidelines for their admission.

First, courts must determine whether the proposed evidence is an animation or a simulation, which carry different standards of admissibility. Computer-generated evidence can be either demonstrative or substantive in nature. For example, animations are generally considered to be demonstrative evidence, as they are usually offered as a visual aid in support of witness testimony. See, e.g., People v. Cauley, 32 P.3d 602, 606–07 (Colo. Ct. App. 2001); Hinkle v. City of Clarksburg, 81 F.3d 416, 425 (4th Cir. 1996) (citing Datskow v. Teledyne Continental Motors Aircraft Prods., 826 F. Supp. 677, 686 (W.D.N.Y. 1993)). Animations do not purport to be scientific recreations of actual events, but rather visual representations of a witness’ recollection or understanding of events. Clark v. Cantrell, 529 S.E.2d 528, 535 (S.C. 2000). Nonetheless, a thoughtfully conceived animation can have considerable impact on jurors’ understanding of an event at issue in litigation.

On the other hand, simulations are generally considered to be substantive evidence. Id. at 535 n.2. See also Commonwealth v. Serge, 896 A.2d 1170, 1175 (Pa. 2006) (using the animation/simulation distinction). Simulations are computer-generated models or reconstructions based on scientific principles and actual data relevant to the events giving rise to the litigation. Harris v. State, 13 P.3d 489, 494 n.6 (Okla. Ct. Crim. App. 2000), cert. denied, 532 U.S. 1025, 121 S. Ct. 1971 (2001) (citing Kristin L. Fulcher, Comment, The Jury as Witness: Forensic Computer Animation Transports Jurors to the Scene of a Crime or Automobile Accident, 22 U. Dayton L. Rev., 55, 58 (1996)). Whereas animations are depictions of fact witness testimony, simulations can give rise to expert testimony.

Second, after the initial animation/simulation determination has been made, courts must consider the foundational evidentiary requirements for each. See, e.g., State v. Sayles, 662 N.W.2d 1, 9 (Iowa 2003). For animations, general requirements applicable to all demonstrative evidence must be shown (i.e., that the evidence is authentic, relevant, fair and accurate, and not substantially prejudicial). See, e.g., Fed. R. Evid. 401, 403. By contrast, simulations are subjected to a heightened scrutiny appropriate for science-based evidence. The proponent of a simulation must show that it is “based upon sufficient facts or data,” which “are of a type reasonably relied upon by experts in the particular field,” that the simulation is “the product of reliable principles and methods,” and that the supporting expert witness (i.e., the expert that will introduce and explain the simulation) “applied principles and methods reliably” when creating or using the simulation. Fed. R. Civ. P. 702, 703.

There are some common objections to animation and simulation evidence that counsel should anticipate (and employ). Because simulations are generally offered in the context of expert testimony, challenges to this evidence often will be made in the context of Daubert motion practice. Computer-generated evidence is also usually generated late in the course of pre-trial preparations, and therefore counsel should disclose the evidence within a reasonable time before trial to forestall timeliness objections.

Counsel should also consider requesting that cautionary or limiting instructions be given to the jury. Requests for such instructions are nearly always granted and are becoming standard in many trial courts. Appropriate cautionary instructions should address the nature of computer-generated evidence as well as the weight that it should be given by the jury in its consideration of all the evidence of the case. In particular, the instructions should include (1) an admonition that the jury is not to give the animation or simulation more weight just because it comes from a computer; (2) a statement clarifying that the exhibit is based on the supporting witness’ evaluation of the evidence; and (3) in the case of a an animation, a statement that the evidence is not meant to be an exact recreation of the event, but is, instead, a representation of the witness’ testimony.

Computer-generated evidence has become more and more common in today’s courtrooms, and nearly every state and federal circuit has addressed its use. For further information on this topic, including a compendium of recent case law in the 50 states and 11 federal circuits, please view “The Use of Computer-Generated Animations and Simulations at Trial,” at

Authored by Caroline D. Walker

Caroline Walker, Butler Snow Law Firm