Expert Demonstrative exhibits occupy a unique place in the courtroom. Unlike evidentiary exhibits, they are a type of proof put before a jury with respect to which the trial attorney has Aartistic control. A trial attorney's job is persuasion, and the persuasion of a jury need not be limited to the spoken words of the attorneys and witnesses, the dry evidence of documentary exhibits, or the bewildering packet of instructions submitted to the jury.
Jurors, who are presented with days of often tedious witness testimony, are much more likely to remember a visual aid that explains the significance of the testimony to them than the exact words of the witnesses or attorneys. Demonstrative exhibits are an invaluable tool for demonstrating a concept of proof to the jury.
In addition to their immediate visual impact, demonstrative exhibits can often be used with multiple witnesses, and are often left in view of the jurors for long periods of time, further reinforcing their persuasive effect, and essentially allowing ongoing argument during your examination of both fact and expert witnesses.
Demonstrative exhibits are liberally allowed in California. While judges have broad discretion to permit the use of demonstrative exhibits, they are generally inclined to allow counsel to use such exhibits to assist the jury in understanding the case. Such exhibits simply make the trial more interesting and understandable to the jurors.
What should your exhibits consist of?
The best demonstrative exhibits are those that have been meticulously thought out, vetted, tested and prepared. The process for choosing demonstrative exhibits should begin at the inception of your case, and must be a fluid one. What is the theme of your case, and what one exhibit might best represent it? Is a time line your strongest argument? A depiction of a scene? Don't limit your demonstrative evidence to proving your case; sometimes the best exhibits disprove the opponent's case. What about an extensive list of “amazing coincidences" that would have to occur for your opponent's story to be true?
Do determine what the point is that you are tying to make. You should never use demonstrative exhibits just for the sake of making your presentation interesting. What is the point or concept are you trying to illustrate? Demonstrative exhibits can be devastating to your opponent. They can show how simple it would be to put a guard on a piece of equipment or repair a dangerous condition. They can show how it would have been impossible for a witness to have seen something they testified they saw. But a common mistake attorneys make is presenting a mock up of something just so they can see what they are dealing with. If your exhibit is vague, and your opponent is clever, he or she will figure out a way to use your exhibit against you, a devastating effect.
Do make sure your exhibits take your opponent's case into consideration. Your exhibit should do either or both of two things: bolster or prove your case, and/or disprove your opponent's. The most well thought out exhibits will do both.
Do pay attention to every detail. If you intend to use a mock up of an accident scene, make sure that it will serve your every purpose in the case. Pay attention to the smallest details, as some juror will. Your inattention to the size of a peripheral building might make it look to a juror like your eyewitness could not have seen the accident, or the height of a object might appear more or less than it actually is. Such small details might then be brought up by a juror during deliberations and might prove fatal to your case without you ever knowing it was even a factor.
Do have your demonstrative exhibit linked to an expert or fact witness. Judges may allow general use of demonstrative exhibits prepared or supplied by counsel for the purpose of assisting the jury in understanding witness (lay or expert) testimony, such as the use of a model airplane or model car. However, if a demonstrative exhibit, or its use, is in any way testimonial, it will need to be presented through an appropriate witness, and a proper foundation laid for its use through the testimony of that witness. For example, while a lay witness would probably be allowed to use a generic model airplane to show how he or she saw it falling out of the sky, a lay witness would probably not be allowed to use the same model for anything if it had been prepared to depict structure damage from an alleged manufacturing defect.
Do remember, timing is everything. You should disclose your demonstrative exhibits just before expert depositions begin. You should make sure your opponent's experts see them before you take their depositions. At their depositions, ask them if they have any opinions or criticisms of your demonstrative exhibits. While the court may still allow your opponent to construct his or her own demonstrative exhibits in response to yours, you will have a strong argument that they should not be able to present further expert opinions (or exhibits) or testify to opinions they did not testify to at their expert deposition.
Do remember, your exhibits will be attacked. After you construct a mock-up or preliminarily design of your demonstrative exhibits, try it out on colleagues, friends, family, anyone who will give you five minutes. The reactions you receive will be invaluable. They will allow you to judge whether your exhibit imparts what you want it to, whether it suffers from confusion or creates a misunderstanding, and most importantly, whether there might be a better way to demonstrate the concept, condition or fact that you are trying to demonstrate. While your experts will hopefully be able to help you as well, your case will not be tried to experts. It is imperative that you vet your exhibit thoroughly. One comment that the exhibit seems to kind of help the other side, should send you scurrying back to the drawing board.
Do make sure your exhibit can be easily and quickly modified. Judges will often sustain an objection to wording, notations or labels on exhibits, and order that an exhibit be changed, modified or deleted altogether if you want to use it. These changes can be quickly made if the exhibit is stored on a computer, and a new blow-up generated. You should assume that some detail of your opponent's objection will be sustained. Where using detailed, moving computer generations or animations, make sure you have the judge rule on any objections early enough so you can have any necessary corrections made. For these reasons, it is a good practice to keep labels, explanations and other text on exhibits to a bare minimum, and let your expert supply the more detailed explanations. He or she can skirt around objections and find a form to supply the information without being stopped in his or her tracks - like you will be if the Judge sustains an objection to a label at a critical part of your computer animation.
Do make sure your exhibits can be clearly seen by all jurors, the judge and opposing counsel. Exhibits that cannot be clearly seen by all of the jurors will have a negative effect, making those jurors who can't see the exhibit feel excluded. If possible, in addition to your large exhibit, distribute small individual copies of the exhibit to the jurors. Don’t let opposing counsel constantly interrupt the flow of your presentation with “Your Honor, I apologize, but I can’t see the exhibit.” And rest assured that if the judge cannot see it, you will be stopped until he or she can.
Do make sure you have selected the best medium for your exhibits. You have a wide array of mediums to chose from: video, animation, stills, blow-ups, multiple TV monitors, multiple computer monitors, overhead projectors, fold outs, or the ancient art of free hand sketching. Make sure that the message is conveyed through the most suitable medium.
Do not conduct your testing in the courtroom. A demonstrative exhibit that you tell the jury will do “x”, and when you hit the button, does “y”, may be the last of your case. Do not use exhibits that rely on wheels, lubricants, electricity, gears, bearings, gravity or good fortune in the courtroom. If you are going to use an exhibit in a trial that incorporates any type of essential predictable movement, have your expert video tape it in operation before trial, and show the videotape at trial. If something can go wrong with an exhibit in the courtroom, assume it will. The seconds that pass while you or your expert try to figure out what simple reason caused your exhibit not to work will be the longest of your life. A re do after lunch will not help. Your case is in trouble.
Do not overspend on demonstrative exhibits. You do not want to spend tens of thousands of dollars on demonstrative exhibits, especially where your adversary takes a much more frugal approach. A jury will be turned off if they learn that you have spent $50,000 or $100,000 on a computer animation. That is more money than most of them make in a year, and while it may seem reasonable to the seasoned litigator, it will just seem like a gross waste to the jurors and allow your opponent to note during closing “I don’t get it. If their case is so clear cut, why would they have to spend all that money trying to convince you?”
Do not make your demonstrative exhibit too complicated. Often demonstrative exhibits designed by experts or “exhibit professionals” suffer from too much detail, or over complication. Remember that you are trying the case to a jury of lay persons, and that it is your job, and that of your exhibits, to bridge the understanding gap between the jury and your experts, not impress other experts or counsel.
Do not fight over your exhibits. Opposing counsel may ask for the first time, in front of the jury, if they might borrow your exhibit during their examination or argument. You are now caught either objecting to or protesting this request, or agreeing to it, without further comment. If you attempt to refuse, you will likely look petty and argumentative to the jury, or worse yet, like you are worried about or hiding something relative to your exhibit. If you cheerfully agree, you had better hold your breath for what may come next, as opposing counsel pulls out their massive black marker and goes to town on your exhibit. As a practice, you should ask the court as a pretrial matter that any request by opposing counsel to address your demonstrative exhibits be raised, discussed and if necessary ruled on outside presence of the jury. While the trial judge may still consider this request a waste of his or her time, it is a necessary precautionary measure, and probably would serve as a objection preserving your right to a later appeal if counsel uses your exhibit in a prejudicial manner.
Do not overdo it. With demonstrative exhibits, less is more. One great exhibit will serve you much better than 4 or 5 mediocre ones.
A Cautionary Note:
Judges usually disallow the use of particular demonstrative exhibits for totally predictable and avoidable reasons:
Their prejudicial effect outweighs their probative value. California Civil Code Section 352 provides that, The court in its discretion may exclude evidence if its probative value is substantially outweighed by the probability that its admission will (a) necessitate undue consumption of time or (b) create substantial danger of undue prejudice, of confusing the issues, or of misleading the jury.  It is unlikely that any judge would allow the use of a demonstrative exhibit that showed in slow motion detailed close-ups of how each of plaintiff's bones broke during a crash sequence. A judge would, however, likely allow an illustration of a body showing pins, plates and other medical devices present in plaintiff's body, post recovery.
They are dangerous. While it sounds elementary, make sure your exhibit is not constructed in a manner that might injure someone. Make sure sharp edges are covered, it will not easily tip over, or in some way pose a threat to the safety of the jury, counsel or courtroom personnel. Make sure it can be presented without blocking fire exits, doorways and other essential areas. If necessary, see if the judge will allow you to display the exhibit in a larger room in the courthouse, and take the jury to see it. Videotaping larger exhibits is always an option.
Their use will entail an undue consumption of time. Think of your use of demonstrative exhibits as part of a play. When you go to a play, you do not expect to see the actors getting dressed, or the stage hands setting, making or assembling the props. Nor are judges inclined to subject the jury to your backstage machinations. You should have your exhibits assembled, working and ready before the jury enters. Ask the court personnel or judge to allow you to set up any involved demonstrative exhibits before court, at lunch or before or after trial hours.
They contain factual inaccuracies. A judge will likely not let you use a model of a convertible car to demonstrate how an SUV roll over occurred. A judge should not let you use an exhibit that contains a time line that has times, dates or events inaccurately portrayed.
The demonstrative exhibit is really an experiment, presented without an adequate foundation that 1) substantially similar conditions existed to those at issue in the case, and/or 2) that the scientific techniques or principles relied on have not gained general acceptance in the particular scientific field at issue. For example, in allowing counsel to present an exhibit that allows the jury to “see what could be seen under certain lighting conditions” a judge would certainly require that some generally accepted scientific basis was utilized to confirm substantial similarity of light conditions in the exhibit to those at the time of the incident.
A picture is worth a thousand words. Demonstrative exhibits, if utilized properly, can help you win a case. If handled improperly, they can cause irreparable harm. They should be handled with the utmost care and caution throughout every phase of your case.
 Demonstrative exhibits are distinguished from in-court or out-of-court experiments, which will be admitted only when a substantial similarity of all conditions are demonstrated. For substantial similarity requirement regarding experiments, see People v. Gilbert, 5 Cal. App. 4th 1372 (1992).
 See Culpepper v. Volkswagen of America, 33 Cal. App. 3d 510, 521-522 (1973) (Under section 352 of the Evidence Code, the trial judge has wide discretion in admitting the results of demonstrations, experiments and will be reversed only when there is an abuse of discretion.).
 DiRosario v. Havens,196 Cal. App. 3d 1224 (1987) (Videotape reconstruction of automobile accident based on eyewitness statements, police reports, and expert=s visit to scene of accident was admissible in wrongful death action; conditions of videotape were substantially identical to those encountered by driver, and videotape afforded visual confirmation of testimony of other witnesses). People v. Boyd, 222 Cal. App. 3d 541, 565-566 (1990) (The court viewed the film and ruled that foundational requirements for its admission had not been met. The court explained that it thought the human eye could see more than the film showed, and that no witness testified that the film was an accurate representation of the lighting condition on the night of the crime).
 Kennemur v. State of California, 133 Cal. App. 3d 907 (1982) (A party's expert may not offer testimony at trial that exceeds the scope of his deposition testimony if the opposing party has no notice or expectation that the expert will offer the new testimony). But, newly decided Easterby v. Clark 171 Cal. App. 4th 772 (2009) offers a new twist to this long standing rule by explaining that an expert can, at trial, go beyond deposition testimony offered as long as the opposing side is explicitly notified that such expert will Aoffer an opinion that was different from the opinion he offered during his deposition,” Id. at 780, and that the opposing side has time to retake the expert=s deposition Ain light of his changed opinion and prepare for cross-examination and rebuttal of his [email protected] Id.
 See People v. Olguin, 31 Cal. App. 4th 1355 (1994); People v. Avila, 38 Cal. 4th 491 (2006) (Relevant evidence may be excluded if it creates a substantial danger of undue consumption of time or of prejudicing, confusing, or misleading the jury.)
 Maricela C. v. Superior Court, 66 Cal. App. 4th 1138 (1998) (State=s strong interest in prompt and efficient trials permits the nonarbitrary exclusion of evidence). See also Notrica v. State Compensation Insurance Fund, 70 Cal. App. 4th 911 (1999) (Trial court=s excluding evidence of State Compensation Insurance Fund=s (SCIF) executive committee=s reaction to liability verdict in insured=s action alleging breach of covenant of good faith and fair dealing was within its discretion under court rule governing evidence that is more time consuming than probative).
 Smith v. Aggola, 27 Cal.App.2d 750 (1938) (In action for injuries sustained in collision between truck and automobile at intersection, the admission of a small drawing of the intersection, made by an engineer, was not error, where the accuracy of the drawing was not denied). See also DiRosario v. Havens, 196 Cal. App. 3d 1224 (1987) (Videotape reconstruction of automobile accident based on eyewitness statements, police reports, and expert=s visit to scene of accident was admissible in wrongful death action; conditions of videotape were substantially identical to those encountered by driver, and videotape afforded visual confirmation of testimony of other witnesses).
See People v. Gonzalez, 38 Cal. 4th 932 (2006) (Videotape of crime scene was inadmissible in capital murder trial to show lighting conditions at time of shooting committed after sunset, as it did not accurately portray those conditions; not only did expert testify that minimum amount of light needed for video camera to record was greater than that needed for human eye to see, there were other differences between videotape and actual conditions). See also People v. Gilbert, 5 Cal. App. 4th 1372 (1992) (Trial court could refuse to admit demonstration evidence offered by lewd conduct defendant consisting of models who would reenact events to which child victim testified, where victim had been between 3'6" tall and 4' tall, weighed between 70 and 80 pounds, and was 11 years old, and proposed model was 5'1" tall, weighed 94 pounds, and was 36 years old; defendant failed to establish conditions of experiment would be substantially similar to alleged occurrence at issue).