Using an Animation or Simulation? Be prepared to defend it!

If you want to use an animation or simulation in a courtroom to show what you believed happened in a crash, make sure it is completely based on the evidence. Software programs can easily be used to create a movie that is not based on facts and is not even physically possible. Simulations of cars flying off a road and spinning out of control may look impressive, but only if the vehicle’s path can be completely validated by the evidence that was found at the scene.

Since crash reconstruction is far from being a new science, you may think your presentations will automatically be accepted in court. However, as recently as May 2013, in a case brought before the Montana Supreme Court, an attorney argued that the testimony of a Crash Reconstruction Expert Witness “…was so utterly lacking in foundation that it should never have seen the light of day in the courtroom.”(1)

In this case, the reconstructionist had created a simulation in Engineering Dynamics Corporation’s HVE program using measurements he took at the scene and information in the Montana Highway Patrol’s report. He was able to explain all of the physical information used as input variables in the simulation and his testimony was ultimately accepted. While it is possible to get a crash simulation or animation accepted in court, you must be prepared to justify all of the input provided to the software, or risk having your presentation thrown out. 

What’s the Difference Between a Simulation and an Animation?

The Crash Zone and The Crime Zone do not perform simulations, instead they have tools that can be used to create animations. Reconstructionists can use animations as a powerful visual aid to support their testimony. So, what’s the difference between an animation and a simulation? Morgan Smith, a California attorney and president of Cogent Legal, claims “A simulation is much more difficult to get into evidence than an animation.” He explains it like this:

“…The basic difference is this: If the presentation is used simply to illustrate an expert’s or witness’s description of what happened, that’s an animation and it’s considered demonstrative evidence only; i.e. it shows real evidence, but is not evidence itself. However, if an expert has to rely on a computer model or program to tell him or her what happened, that’s a simulation, and it’s “real evidence” that requires all the levels of foundation and acceptance of methods used by the expert to create the simulation before it can be admitted into evidence…Animations Show the Expert Opinion   –  Simulations Are the Expert Opinion…” (2)



While an accurate simulation is a very powerful tool, it’s important that the software-generated simulation doesn’t become a replacement for doing an accurate reconstruction of the event. The reconstructionist still must perform an exhaustive search for physical evidence, take accurate measurements and photographs, and create a detailed diagram of the scene. An accurate diagram can then be used to obtain distances and angles for a traditional conservation of momentum analysis.

The Crime Zone and Crash Zone have everything you need to turn your measurements into a detailed diagram of the scene. Whether you use a tape measure, total station, or 3D laser scanner, you can easily bring the measurement data into Crash Zone. These programs have a comprehensive set of drawing and editing tools that only a true CAD program can offer, yet they are designed to be easy for an investigator to use. If you are investigating a crash you can apply the many calculation tools in The Crash Zone, including critical speed calculator, multi-surface skid analysis, momentum calculator and combined speed calculator. There is even a crush calculator that calculates the energy and equivalent barrier speed, and creates a graphical crush model from your data.

Get Your Animations Accepted in Court

Crash Zone animationIf you intend to present an animation as part of your case in court, you must be confident that you can prove it is based on the physical evidence. CAD Zone applications have easy-to-use animation tools that let you show the movement of up to four vehicles, bullets, people, or any other symbols. You draw the path of the movement and place Key Event Points where each object changes velocity or direction. If you place these Key Event Points using the exact measurements taken at the scene, such as the location of skids, gouge marks, vehicle final rest position, and so on, the animation will be accurate.

According to crash reconstructionist, Bobby Jones of Knoxville Tennessee, “To express your ideas by showing objects in motion is far more impressive to anyone viewing it than to hear words with static diagrams.” For example, to explain a crash at an intersection with just static diagrams Jones said he would have to show a diagram of the intersection, then a diagram of the vehicles at impact, and then a series of diagrams at various time intervals. “Watching this unfold in real time as an animation is much more effective.” Jones argues, “We can watch the whole crash, then go back and look at it one frame at a time. Juries comprehend such animations better, and the retention is much higher than with just words and static diagrams.”

In his 32 years as a reconstructionist, Jones has used many different diagramming, animation, and simulation software applications. For creating animations, he prefers to use The Crash Zone. “The animation tools in Crash Zone are second to none. It’s very easy to create accurate and effective animations. However, the visual aspect is only part of a forensic animation. The investigator must also be able to explain it. With the Crash Zone’s animation tool, you can save each frame as an individual image and obtain a comprehensive report of all the data points – the very backbone of any animation.”

Most reconstructionists agree that using an animation or simulation in a courtroom presentation can be an effective way to show their case. However, it’s highly probable that any investigator who testifies in court will be called upon to prove their reconstruction. It’s critical that you only build these visual aids based on the physical data found at the scene and that you are prepared to defend them.  (Click here for more information on The CAD Zone’s animation tools.)


(1) State Law Library of Montana, Case DA 12-0322 , 5/7/2013, Wheaton V. Bradford.
(2) Cogent Legal Blog, author Morgan Smith, 5/24/11,  “Why Trial Attorneys Need to Know Computer “Animations” vs. “Simulations” for Evidence”

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