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Thinking creatively about using expert witnesses

By Jessica E. Bustos

Jessica Bustos

The concept of an expert witness can cause many lawyers to cringe over the prospect of high fees and complicated scientific testimony.

Consider changing that thought and embracing the use of expert witnesses in your cases. The legal definition of an expert and requirements for their testimony are not as difficult to establish as you might think. There are experts all around you that you can deploy at little to no cost. Using some creative thinking about experts can assist you in proving your case and save your client or organization money, which ultimately improves the administration of justice.

Where can an expert be used?

The evidence code provides for expert witnesses to educate the jury involving an issue beyond common sense. Most often we think about physicians, economists and scientists. However, the law allows for a greater variety of experts than that. Therefore, it is important to review your case and look at whether an expert can help clarify an issue or connect the evidence in your case.

Experts can help prove direct elements in your case, circumstantial evidence and even explain why your evidence came out a certain way. Proving an element directly is what you may ordinarily think about, such as using a handwriting expert to prove the signature belonged to a person, an accident reconstructionist to recreate what happened in a collision case or a gun store owner to establish that a firearm is an assault rifle. Sometimes you may want an expert to help explain something other than direct evidence, such as the absence of a piece of evidence. Some examples include the lack of medical treatment, the lack of damage to a vehicle or lack of injuries when these things might be expected.

Additionally, an expert can help explain why a person testified in a certain way in the case. Courts have approved expert testimony in cases such as a developmentally disabled witness’ reaction to a perceived danger (People v. Dejourney, 121 Cal. App. 4th 1091, 1106 (2011)), a battered woman who minimizes what happened in the case (People v. Riggs, 44 Cal. 4th 248, 292 (2008)) or even testimony regarding a parent who does not immediately report the complaints of child molestation to authorities (People v. McAlpin, 53 Cal. 3rd 1289, 1298 (1991)).

It is important to note that in some of these examples, the expert evidence was used to rehabilitate a witness whose credibility was at issue, and only relevant after their credibility was contested. Nonetheless, they are valuable examples of when you can use expert testimony to explain the way evidence was presented in your case.

Testimony must cover more than the common experience

Expert testimony must be beyond the information a juror may already know. Evidence Code section 801 limits expert testimony to a “subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact.” The more easily the testimony can be understood by the jury without the need for an expert, the more likely the expert’s opinion will be excluded. However, courts have allowed expert witnesses to testify to subjects that the jury might already have knowledge about when the testimony adds to their “common fund of information.” People v. McDonald, 37 Cal. 3d 351, 368 (1984). Further, courts have allowed an expert to give an opinion even if it’s related to common experience if it’s still useful to assist the trier of fact. See People v. Dejourney, 121 Cal. App. 1091 (2011). Therefore, it is imperative to think creatively about how the expert can be useful to your case as well as how this expert adds information beyond a jury’s common experience such that the expert is necessary for your case.  

Expert subject matter requirements

Evidence Code section 801(b) requires the subject matter the expert opines about to be, “[b]ased on matter (including his special knowledge, skill, experience, training and education) perceived by or personally known to the witness or made known to him at or before the hearing, whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates, unless an expert is precluded by law from using such matter as a basis for his opinion.” While that seems a little confusing and complicated, it is meant to serve as a broad definition for all types of experts to ensure that their expertise is reliable and related to their testimony.

Essentially, the subject matter must be something that the expert knew about or can learn about at the hearing and provide an opinion on. For example, a DNA expert can testify about the analysis he conducted on the evidence, while an accident reconstruction expert can testify about the photos she saw of the scene, of the vehicles and of her determination of what happened in the collision. Some experts can also be presented with the information at the hearing in the form of a hypothetical question and asked for their opinion after hearing the hypothetical.

The expert’s opinion on the subject matter must be based on research, practices, experiments and material that experts in that same field typically rely on in rendering opinions. For example, the DNA expert would draw on research, reading books on the subject, performing experiments and their prior analyses on the subject of DNA to render an opinion in the current case. Another example is a real estate agent who looks at the values and sales in the market to decide the value of a given property. This ensures that the expert is drawing the information from a rational database and that the information is related to the subject they are testifying about. It also prevents an expert from drawing a conclusion which is speculative or not rationally based on the witness’s expertise. Garrett v. Howmedica Osteonics Corporation, 214 Cal. App. 4th 173, 185 (2013).

Expert witness qualifications

Evidence Code section 720 sets forth the requirements for a person to testify as an expert witness. It states, “[a] person is qualified to testify as an expert if he has special knowledge, skill, experience, training or education sufficient to qualify him as an expert on the subject to which his testimony relates.” This code section, along with Evidence Code section 802, relates to how you can use an expert witness in your case and admit their opinions into evidence. The trial court judge will determine whether a witness is qualified to testify as an expert. Keep in mind that an expert’s qualifications go to weight, not admissibility, so once you have met the basic requirements and the trial judge assents to the testimony of your expert witness, the jury can still hear the expert’s opinion and make their own determination as to its weight.

You will still want to provide a strong foundation for the witness’ expertise to show why they are knowledgeable and credible. The jury should hear everything about their education, training and experience which is relevant to their opinion on the subject matter. Not only does this meet the requirements of sections 720 and 802, but it also shows the jury that your expert knows about the subject, has experience in the subject and can be trusted to give an opinion on the subject. It is the “why we should listen and trust you” factor. In examining the witness, it is important to show a nexus between the witness’s experience, why it is relevant to your case, why it helps to explain an issue and why the witness’s explanation should be trusted.

Tips to secure cost effective experts

Lastly, experts don’t have to be costly. As a young attorney, you may not have the resources to secure expensive experts or your clients may not be able to afford the cost of the expert. To ensure that your clients are well-represented and that you have the best opportunities to secure justice in your case, it is helpful to think outside of the box in terms of who you can utilize as an expert. You can secure low-cost experts by building your personal and professional networks. An expert does not need to have a professional degree; they only need to have specialized knowledge or skill in the area that you want to teach the jury about. It also helps to have someone who can relate to the jury and who can break down the subject for a lay juror. Additionally, it does not matter that they have never testified as an expert before – otherwise, there would never be experts. McCleery v. City of Bakersfield, 170 Cal. App. 3d 1059, 1066 (1985).

Consider using graduate students, retirees or people who specialize in a trade (mechanic, electrician, physical therapists, etc.). Most graduate students have a current specialized knowledge base of the subject area and have also done some clinical work, so they have both the relevant education and field experience. Further, they are more apt to be available, will charge less and are eager to use this experience as a resume builder. Also, consider using people around you. For example, you can use your local mechanic to describe how a transmission works or a carpenter to describe safety precautions. Finally, consider asking retirees. People continue to learn and develop their skills even after retirement. Some retirees may be interested to help, more available and may cost less.

Some additional things to consider include ensuring you comply with discovery and disclosures of your experts, establish the Kelly/Frye requirements if you have a new scientific technique, and ensure that you write a detailed motion explaining why you are using an expert in your trial. Hopefully with some creative thinking and knowledge of the evidence code, you can more confidently secure and present expert evidence in your case to better achieve justice.

Jessica E. Bustos is a deputy district attorney in the Stanislaus County District Attorney’s Office and a member of the California Young Lawyers Association.