More articles by James O. Harris Expert Witness Record Requirements

Get notified about new articles - join the ExpertPages Mailing List now

There have been numerous court decisions that warrant the preservation of physical evidence in traffic accident litigation. The First District Court of Appeals in California has issued a ruling requiring wrecked cars be preserved "if they should have known it was needed as evidence by an opposing party in the case."

Shortly after this ruling, a case involving a fire in a motor home was dismissed due to the fact that the defendant had not been given the opportunity to examine the burned vehicle. The incident the allegation had been based on occurred over two years before and the insurance company had long since disposed of the vehicle. The only alternative in these cases is to make certain that all parties joined in an action have had ample notice to conduct an examination of the evidence. Even this may not be sufficient in the case of fatalities or considerable damages. It may be safer to preserve the vehicle entirely until litigation is complete.

What about cases where parts have been removed for testing or to be held separately as evidence? Extreme care must be exercised. In Nally v. Volkswagen of America, Inc., 405 Mass 191, 539 N.E. 2nd, 1017 (1989), the court stated "where an expert has removed an item of physical evidence and the item has disappeared, or the expert has caused a change in the substance or appearance of such an item, in such circumstances that the item in its original form may be material to litigation, the judge, at the request of a potentially prejudiced litigant, should preclude the expert from testifying as to his or her observations of such items before he or she altered them and as to any opinion based thereon."

In other words, if the expert loses the item or alters it in any way by testing, neither that item nor your expert's testimony regarding his opinions as to its relevancy to the accident will be allowed. If you allow someone to remove, test or hold evidence, make sure they understand it must not be altered or destroyed until the other litigants have had a chance to examine it in its original state.

Once you have the evidence in hand, you must consider the best way to present it to a jury. There are dozens of ways to present evidence. Some types are simple and convey the message quickly and clearly. Others are more involved and may be needed where complex issues or situations have to be presented. Still others, although simple in appearance, are difficult to produce and can be expensive. In any instance, it is imperative the attorney is aware of the different types of trial exhibits, the advantages and disadvantages of each and the cost of production for each type.

For traffic accidents, the most common exhibit is the scale diagram. Prepared by an accident reconstructionist, these are simple in appearance but the amount of data required to prepare one can be tremendous. A diagram can present any number of objects, vehicles or people at an accident scene. The term "scale" means the drawing will accurately represent the size and location of any object on the drawing in relative distance and size to any other object. A common scale size is, for example, 1 inch on the drawing equals 5 feet on the ground at the accident scene, or 1" = 5'. Larger scale sizes are possible but the drawings tend to become to big to handle easily:

The more items that must be displayed, the more information that must be gathered from the scene or from photographs taken at the scene. The person preparing the diagram will first conduct a survey of the accident location. During this survey, buildings, road edges, curves, trees, lane lines, traffic signs and other fixed objects will be located in his survey notes. These notes represent the scene numerically and this information is then transferred to a drawing as a graphic representation. This type of exhibit is static so several may have to be prepared to show various elements at different points in time.

Current technology allows a draftsman to enter the numerical survey data into a computer and the computer produces the actual drawings on a large format printer or plotter. The plotter is capable of producing very accurate results in many colors. The production of several drawings, each showing elements of interest at different time intervals, is much faster than producing separate drawings each time as the same basic information is used to create the scene. The moving vehicles are placed at different locations on each successive diagram.

Diagrams are very useful for demonstrating sight distances when there is a view obstruction for one of the drivers. Sight lines, laid out from one driver's position to another and viewed from overhead, give a clear picture of what each person could see as the event unfolds.

Diagrams of the accident scene without the vehicles in place are also useful. Witnesses or drivers can draw on the diagram, placing themselves or others at various points or demonstrating what they believe happened to cause the accident. Diagrams can also be mounted on sheet metal with the cars, people and other movable objects on magnets.

Diagrams are a low technology exhibit, no electronic equipment is required to make them work. They are friendly in that the jurors will not be trying to figure out how the technology works but will be concentrating on the evidence presented.

This type of exhibit is probably the most cost effective. The information they contain is not only used to present evidence but is used in many collision situations by an expert to determine time, speed, distance and collision avoidance tactics.

Scale Models

One step up from diagrams is the scale model. The difference between diagrams and a model is the model has three dimensions. Cars, trees, poles, signs, buildings and people can all be included. If the vehicles are not fixed on the model board, they can be moved and placed by witnesses to demonstrate what happened.

Scale models can be as simple or intricate as desired. They are particularly useful for situations involving vehicles that move in several directions, such as backing up then moving forward, before an accident occurs.

Scale models are more expensive than diagrams but have the advantage of depth. The production of a scale model can be moderate to expensive. The cost is dependent entirely upon the size of the scene to be presented and the number of items that will be shown. Costs can increase if the model is to have any moving parts or lighting installed.

Scale models tend to be fairly delicate so care must be taken in handling and shipping should be held to a minimum.

Video animations are a new trend in litigation and still expensive. Not all accident situations lend themselves to animation. They best show a driver's view and collision avoidance tactics in simple scenarios. This type of exhibit, properly prepared, can almost take the jury to the scene.

Animations can also show the scene from above, just like a scale diagram. This gives the juror a perspective that did not exist to any of the witnesses. They can show "what if" scenarios or recreate accidents that otherwise could not be reenacted.

A tremendous amount of information is required before the animator goes to work. Time, speed and distance must all be determined by an expert in extreme detail. The position of every vehicle going into a collision must be known in intervals of fractions of a second. The view of the driver, blocked by outside objects such as buildings or trees, must be determined. The forces acting upon a vehicle in a collision must be ascertained to show the post-collision travel of the vehicle. Lighting becomes an issue in many animations and an expert in this area may be needed.

If a pedestrian accident is to be animated, the movement of the pedestrian, before, during and after the collision, must be analyzed so a realistic presentation can be made.

Animations contain the greatest amount of information possible and because of this are also the most likely to be rejected by the court. Any misrepresentation of any aspect, no matter how small, can compound the errors in the presentation.

The final cost of an animation must include the cost of having an expert perform all the necessary calculations for the animator to follow. This can be as much or more than the actual production of the video.

Stock animations of some aspects, such as injury mechanisms, are now available. Using these as demonstrative aids, rather than as evidence, can be very cost effective. The same animation can be used for any number of cases involving the same injury mechanism.

Reenacting an accident is different from animations. To reenact a scene, actors, vehicles, videographers, stunt performers and a myriad of details must be attended to.

It is necessary to obtain exemplar vehicles. If the intent is to actually recreate the crash, the vehicles will probably be of little value afterwards so there is considerable cost at the outset. Most likely, they will have to be modified for the protection of stunt drivers if they are used. Modifications include removal of the gas tank and glass, installation of roll bars and other protective equipment and reinforcement of certain parts to protect the occupant. It is possible to rig a vehicle with remote controls and dummies to avoid much of the otherwise necessary modification but this is still an expensive proposition.

The accident scene will have to be secured to prevent the inadvertent intrusion of spectators and routine traffic. This can involve obtaining road closing permits, the hiring of off-duty police officers, renting traffic barricades, insurance and other administrative costs.

The videographer is one of the most important people on the scene. He must be a professional with the proper equipment. It is strongly recommended that broadcast quality beta format cameras, rather than home video recorders, be used. Beta format cameras are capable of extremely high resolution and lighting and color balance can be strictly controlled. If you are going to the expense of reenacting an accident, it is wise to have several cameras all running at the same time from different angles. You may only have one shot unless you have purchased a fleet of exemplar vehicles.

For full reenactments using stunt drivers, a stunt coordinator is required. The coordinator is the person in charge of the action on the set during filming. He is there to insure the safety of all the actors involved. No professional stunt drivers will work without a qualified stunt coordinator on the scene.

Before considering a reenactment, it is necessary to determine if it can be accomplished at all. There are situations so unique, and collisions so great, it may be difficult or impossible to recreate the scenario. If this is the case, consider an animation instead.

Skid demonstrations, without an impact, are very useful for showing skid distances. Vehicles are equipped with a recording accelerometer, which gives an immediate indication of the vehicle’s speed through the skid. A chalk bumper gun can be installed on the side of the test vehicle to show where the brakes are first applied and where skidmarks first become visible. This is a very effective and easy to understand demonstration of vehicle skid speeds.

Still photography is an exhibit that has been around a long time. The cost of photo production has dropped dramatically as technology has improved. Huge enlargements of very small objects, called macro-photography, is possible. The filaments of automotive taillights are one subject that lends itself well to macrophoto displays.

Photographs of injuries while a person is in the hospital can graphically show the visible injuries or scars that will be with the victim for a very long time. Professional photographers with portable studio lighting can take photos of a much better quality than the amateur with a camera and small flash.

Crash damage, properly recorded, can be a very dramatic exhibit. Jurors tend to equate damage to speed and if that is the point you are trying to make, one picture is worth a thousand words. When taking pictures of wrecked cars, remember, film is cheap compared to the amount of information it contains and the value of the one great photo to a jury.

Aerial photos are another option to diagrams and scale models. Aerial photos can be taken as obliques, that is outside of an airplane window at an angle to the ground, or as a true vertical. True verticals are taken with the camera pointing straight down to the ground. This results in a view similar to a scale diagram but includes many details that may otherwise be ignored during a ground survey.

Aerial photography is a specialty of many photo firms and for good reason; it is not as simple as it sounds. There are many factors in aerial photography you do not encounter on the ground such as vibration of the aircraft and strong shadows. A true vertical must be taken no more than 5 degrees off vertical. Getting the camera into this position requires aircraft especially equipped for just such an endeavor.

Ground photography can record many details otherwise difficult to record or explain. A driver's view as he approaches an intersection can be shown by taking a photo from the driver's height on the approach. Interior views of vehicles can show places where the occupant contacted panels and controls during a collision.

Court presentations can, and should, be composed of several types of exhibits. The use of various formats, each one complimenting the other, is one way of keeping the juror's interest in the proceedings. Using animations to help explain a sequence of events, a live video of the day in the life of the plaintiff showing the results of the accident, and board graphics to show future losses or reinforcing items of interest regarding liability all make up an effective presentation.

By:  James O. Harris. Email: experts@harristechnical.comWebsite: http://www.harristechnical.com/  Reprinted with permission from James Harris