The Ultimate Guide to Using Expert Witness Exhibits in Court

Anjelica Cappellino, J.D.

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— Updated on June 25, 2020

The Ultimate Guide to Using Expert Witness Exhibits in Court

The purpose of expert testimony is to help fact finders understand scientific or complex facts at issue during trial. In certain cases, an expert’s verbal testimony may be sufficient to convey complex ideas. However, more often than not, other evidence is needed to further explain, illustrate, or summarize the testimony. This additional evidence is usually presented in the form of expert witness exhibits.

Expert witness exhibits present supplemental visual evidence that helps explain, illustrate, or summarize complex expert witness testimony. In some instances, crucial pieces of evidence must be presented as part of the case, and the expert is the only witness through which they can be properly admitted. When physical evidence is admitted as an exhibit, like the expert’s testimony, it becomes part of the trial record. Before any exhibit is introduced through your expert, it is important to keep in mind the impact each will have on the testimony, as well as the outcome of the case.

When Expert Witness Exhibits are Necessary

The forms that expert witness exhibits take can vary as widely as the subject matter of the testimony. Exhibits can be documentary, such as written documents, contracts, invoices, or anything else that falls into the writing category. They can also be physical, tangible items, like a weapon in a murder trial, also referred to as real evidence. Not all exhibits need to be solely visual. Audio and video recordings may also be relevant evidence depending on the case.

Not all exhibits are meant to establish a fact at issue. Demonstrative evidence (as opposed to real or documentary exhibits) is evidence that is meant to explain the facts that the testimony attempts to prove. For example, demonstrative evidence can include charts, graphs, diagrams, or other graphics that illustrate an expert’s testimony.

Experts Whose Testimony can Benefit From Exhibits

Any case may benefit from the use of expert witness exhibits during testimony. However, testimony from experts in certain specialties may achieve additional credibility from the use of exhibits.  For example, medical experts may use medical records (a form of documentary evidence) to testify to a party’s injuries. But additional evidence in other forms might be necessary to successfully explain the extent of the injuries sustained. A real-life model of the patient or the harmed area, such as a made-to-scale model of the bones in the foot, can illustrate the injuries in ways testimony may not. With the advancements in 3-D technology, medical experts can recreate the effects of different injuries, surgeries, and other treatments simply through certain computer programs.

Technology and data models can also help recreate events at issue. For example, accident reconstruction experts can use computer models, virtual technology, and other programs that can recreate a visual representation of a car collision (or other type of incident) with precision and detail. Of course, accident reconstruction specialists are well-versed in scientific methods like time-distance analysis and velocity. But when an expert is evaluating a car collision to a jury, a computer simulation may be far more helpful in explaining principles in practice. As a general rule, when testimony alone may be too complex for the jury to fully understand, use exhibits.

Relevancy of Exhibits

That being said, not all expert witness exhibits are admissible in court. Each jurisdiction has its own governing rules of evidence to which an expert’s testimony must adhere. As a general rule, evidence will not be admissible at trial unless it is deemed to be relevant. Under Rule 401 of the Federal Rules of Evidence (which is followed by all federal courts and the states which have adopted similar rules), evidence is considered to be relevant if “it has any tendency to make a fact more or less probable than it would be without such evidence and the fact is of consequence in determining the action.”

The rule is couched by Rule 403, which permits the exclusion of otherwise relevant evidence if its probative value is substantially outweighed by the danger of “unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly cumulative evidence.” In other words, exhibits will be carefully scrutinized by the court and opposing counsel as to whether they are relevant and not prejudicial.

There are many reasons certain exhibits may be deemed relevant to an expert’s testimony. Anything that can help explain or substantiate the testimony would tend to make a fact more (or less) probable. Particularly in terms of scientific experts, evidence including past studies, experiments, or empirical research will inevitably be incorporated into testimony. However, it is important to note the limitations of the evidentiary rules when evaluating an exhibit’s relevance and value.

Prejudice of Exhibits

Certain expert exhibits, although relevant, may be deemed too prejudicial, confusing, or simply burdensome to admit. Examples of evidence that may be considered too prejudicial to admit include gory, disturbing, or explicit photographs. This can also include representations of injuries or any visual depiction that has the potential to upset the jury. If an injury of a plaintiff or victim in a criminal trial is otherwise fully proven, a court may preclude the admission of explicit visuals that can appease to a jury’s sensitivities or sentiments.

Likewise, exhibits cannot confuse the issues or mislead the jury. Exhibits should work as a supplement to the testimony, not the other way around. There are also expediency considerations which may preclude evidence that would cause delay, waste time, or be considered cumulative. For example, imagine that thousands of medical records, which are already admitted into evidence, fully exemplify an injury at issue. The court may prevent an expert from utilizing additional records that are similar to the previously admitted reams.

Overall, there is a delicate balance that must be met between an exhibit’s relevancy and its unintended prejudicial consequences.

Summary Exhibits: Wrapping up the Case

Summary exhibits provide a summary or breakdown of evidence that can be conveniently and efficiently examined by the trier of fact. For example, exhibits of exhibits may be warranted when voluminous evidence needs an additional summary.

As permitted under Rule 1006 of the Federal Rules of Evidence, such exhibits can be used through the means of “a summary, chart, or calculation to prove the content of voluminous writings, recordings, or photographs that cannot be conveniently examined in court.” They can be any type of meaningful summary of information. Such exhibits may be used in cases where presenting the entire volume of records is unfeasible. These cases include those involving voluminous financial or medical records that cover extended periods of time. Summary exhibits summarize evidence that has been presented. For example, this can include a chart of the pertinent dates and times of every audio recording admitted.

Summary exhibits aren’t always admitted into evidence though. If they are, however, they hold greater weight. This is because the jury will have access to summary exhibits during deliberations. When a trial has been particularly lengthy, summary exhibits offer a concise wrap up of the evidence that has been admitted.

The Best (and Worst) Exhibits for Juries

There is no blanket answer as to whether a certain exhibit will be helpful to a jury. In terms of substance, the evidentiary rules (as well as common sense) dictate that all exhibits must be relevant to the facts at issue and help explain the expert’s testimony. But substance aside, there are numerous forms a piece of evidence can take. Although there is no one right answer as to the best one, a few general rules should be considered.

First, it has been proven that people, by and large, are visual learners. This means that they respond well, and retain information more easily, when presented with some sort of visualization. Working off of this assumption, it would be wise to interject visual exhibits when necessary during an expert’s testimony. Not only can visual presentations supplement the testimony and help with informational retainment, but they also act as a helpful break from the usual routine of testimony. That being said, there are a few pitfalls to watch out for, no matter the form of the exhibit.

Watch out for Low-Tech Courtrooms

No matter how detailed or explanatory a piece of evidence is, the jury must be able to actually see it. This will largely rely on outside factors to which witnesses and lawyers have little control. Attorneys frequently underestimate how the size of the courtroom and the position of the jury box impact the strength of an exhibit. Likewise, a courtroom’s technological capabilities play a huge role in evidence presentation. Many courts are now adding projectors and individual screens within the jury box so each juror can review the evidence as it’s presented.  But not all courts are as tech-savvy. And unfortunately, some exhibits are useless without such A/V support.

At the same time, it is important to avoid cognitive overload. The legal field has been making great advancements in the area of exhibit presentation. However, that doesn’t mean a jury should be overstimulated with visuals on every detail. All written exhibits should be easy to read and formatted correctly. Summary charts should be easy to follow. Graphics should be clear and concise.

The most important thing to remember when using exhibits is the value that they bring to the case. Exhibits that facilitate a deeper understanding of an expert’s testimony should hopefully yield a successful outcome.

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