APU Legal Studies Original

The Limitations Regarding the Testimony of Expert Witnesses

By Dr. Gary L. Deel, Ph.D., J.D.
Associate Professor, Dr. Wallace E. Boston School of Business

I have written previously about my work as an expert witness in different cases. I’ve also described how experts are compelled to conform to court-imposed requirements for the credibility of expert testimony. When experts cannot defend the basis for their work adequately, they may be exposed to Frye or Daubert challenges from opposing counsel who seek to either exclude testimony or disqualify an expert altogether.

  • Topics outside an expert witness’s purview of expertise
  • Legal opinions
  • Opinions on witness credibility

Topics Outside an Expert Witness’s Purview of Expertise

The first area – topics outside a witness’s purview of expertise – is perhaps the most common reason why a court might exclude expert testimony or why expert witnesses might be disqualified. As I noted in a previous article, “part of truly being an expert in one’s discipline(s) means recognizing and acknowledging the areas in which one is not an expert.” But this line can sometimes be a difficult one to draw.

As an example, one of my areas of expertise is in safety and security practices. And because my professional background includes work in the hospitality, travel, tourism, and leisure industries, I tend to help with a lot of cases in these arenas as a consultant and expert.

A lot of my work concerns cases that involve negligent security or safety practices by hotels, casinos, restaurants, nightclubs, cruise lines, airlines, movie theaters, and event venues. I am usually retained by personal injury attorneys (on both the plaintiff and defense side) to help with such cases.

But many of those same attorneys also handle personal injury matters in other industries, such as retail. Cases where customers slip and fall (or trip and fall) in or around stores, groceries, shopping malls, and other public areas are very common.

Since I am a safety expert, it is not at all unusual for attorneys to ask me if I can testify in such cases. For instance, an attorney might use me for a negligence case against a hotel. If he was happy with my work, he might later want to use me again for a case against, say, a large retailer, such as Walmart. This type of occurrence happens all the time.

And to be fair, many of the most basic safety and security principles for premises liability matters tend not to deviate too drastically across industries. For example, sweeping floors and looking out for dangerous conditions are examples of practices that are pretty universal across different settings, whether one is in a hotel or a grocery store. So for these kinds of cases, I might very well be able to help with consulting or expert testimony on solid footing; indeed, I have done so successfully in my career on numerous occasions.

But what about something more innate to the retail industry, such as receiving and inventorying merchandise? Lawsuits related to products injuring customers in stores are fairly common as well.

But this area is an example of a business practice which does not intuitively translate to hospitality or other industries. In fact, there may be unique standards for handling and inventorying of retail merchandise that only a veteran retail industry professional would know.

For these cases, an individual who is not a consummate retail operations expert would probably be better off punting the request for expert witness testimony to someone else. That other person would ideally have better credentials and inarguable industry experience, so that that expert could competently address the matter under discussion.

To be clear, this is not to say that an expert cannot do the necessary research and preparation to offer valid, legitimate opinions on subjects adjacent to his or her areas of expertise. For example, I have a friend who is a mechanical engineer. His potential area of expertise is extremely broad, covering everything from the design of products as simple as a toothbrush to the planning and construction of the most complex manufacturing machines and equipment.

My friend has a unique set of engineering knowledge, skills and abilities that allow him to bring his expertise to bear on many different applications. Clearly, each new case and context requires that he do some research and investigation.

But research and investigation is part of the process for every good expert witness with each new case. The fact that research was needed does not necessarily imply that the expert is not competent to testify.

However, to deviate too far from one’s own area of expertise is to risk the kinds of exclusions or disqualifications in court that can stigmatize an expert’s career for years. So when in doubt, it is often better to err on the side of caution and stick to engagements that fit squarely within the realm of an expert’s dominion of knowledge.

Expert Witnesses and Offering Legal Opinions

A second area in which expert witnesses should generally avoid testimony is legal opinions. Legal opinions from experts are usually not permitted by courts, because a legal interpretation is for the judge to handle, accompanied by supporting information and argument from the case’s attorneys. And expert witnesses should not encroach on these responsibilities.

But what exactly is a “legal opinion”? The idea might seem simple, but in practice it can be a domain filled with gray areas.

For example, another one of my areas of expertise is human resources and employment law. I am an attorney, and I teach classes that focus on these subjects for several universities, including our own University where I teach this curriculum full-time. As an attorney and instructor, I have been retained as a consultant on more than one case in the past involving claims of employment discrimination against employers.

But just because I am an attorney does not mean that I should give a legal opinion. When I am acting as an expert witness in a case, I am still held to the same rules and requirements as any other expert witness.

In these kinds of engagements, drawing the line between a legal interpretation and an industry practice requires careful articulation. For example, suppose an employee sues an employer, claiming gender discrimination in hiring or promotion.

As an expert witness, I should probably avoid offering testimony on what federal anti-discrimination laws are and how they are applied, as this testimony smacks of legal opinion. But if I instead limit my testimony to topics such as the standards and practices customary among employers and implemented to prevent discrimination, this type of testimony keeps a healthy amount of daylight between the actual law and the standards and practices predicated on legal compliance.

Here’s another very common example that I see in my work. If I use the word “duty” in an opinion in court, what does that mean? Opposing counsel will often be quick to jump on an inference that the word “duty” must always refer to a legal duty – and therefore any statement containing this word must amount to a legal opinion.

But this way of thinking is hyperbolic and ultimately untrue, because “duty” has many different interpretations. While this word is commonly used in laws and legal principles, it is also just as commonly used in industry practices supporting proper business operations.

For example, in a safety-related case, I might testify that a hotel has a “duty” to inspect its guest rooms for unsafe conditions such as wet floors or broken fixtures. But do I mean “legal” duty? No, I mean that the hotel owes a commitment – based on the lodging industry’s standards and practices – to make reasonable efforts at maintaining safe premises for its guests.

Whether that industry commitment also translates to a legal duty – and what that legal duty might mean in the lawsuit – is for the attorneys and the judge presiding over the case to deliberate. But all of that is beyond my scope as an expert.

To prevent any confusion, I will sometimes go so far as to overtly clarify in my written or oral testimony, where I feel it is necessary, that certain language I might use should explicitly not be misconstrued as legal opinion. I may offer definitions for any terms that might be used in order to distinguish them from anything that might suggest legal opinions. So in the case of talking about a “duty,” I might testify that I use the word “duty” to refer to a commitment based on an industry standard as opposed to a legal obligation.

Ultimately, the lines between legal opinions and every other type of opinion can sometimes be less than crystal clear. As a result, attorneys will often base their own interpretations of testimony on their strategies and what is most helpful to their clients’ cases. However, expert witnesses should always be mindful of the prohibition against legal opinions and do their best to avoid them, or, at a minimum, proactively clarify any language that might suggest a legal opinion where one is not actually intended.

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Expert Witnesses and Witness Credibility

One final area in which expert witnesses should be reluctant to offer testimony is witness credibility. If a case involves conflicting testimony from different parties or witnesses, for instance, expert witnesses should generally try to remain neutral regarding who or what they “believe” in a case.

Offering testimony on witness credibility can carry the risk that an expert will be accused of bias based on their inclination to believe one witness over another or one accounting of events over another. Commonly, witness credibility issues are regarded as matters to be deliberated by the trier of fact in a case (the judge or jury) and they remain outside the scope of expert testimony.

Typically, courts have mixed opinions on the admissibility of expert witness testimony as to witness credibility – with some permitting it and some not. Even esteemed legal experts disagree on the propriety of such testimony.

However, if such testimony is to be permitted in court, many scholars agree that it should be limited in scope and, where appropriate, should require expert credentials that would support the legitimacy of any such opinions. For example, someone with an education or expertise in psychology might be able to offer testimony about indications of dishonesty or deceptive behavior if such behaviors are observed from a witness.

What about factual circumstances that might suggest implications about witness credibility? For example, imagine that a witness has a history of dishonest behavior, such as a criminal record that includes fraud, deceit and perjury. Another instance would be if there is solid evidence that a witness was paid to make a statement or coerced into testifying in a certain way.

Generally, an expert witness is free to point out such facts to the extent they are incontrovertible. But he or she should avoid making any accusations about truthfulness one way or another, particularly if they lack the requisite expertise to judge such circumstances.

Still, cases involving mutually incompatible witness accounts are extremely common. Many, if not most, of the cases I have worked so far in my career contain elements of disputed facts.

So what is an expert witness to do when faced with conflicting stories from different individuals? There are a few solid approaches to these situations.

First, if there is a preponderance of evidence or testimony one way or another, expert witnesses are generally free to acknowledge this fact. For instance, suppose that Witness A to a car accident says it was raining at the time of the crash and Witness B says it was not raining. If the historical weather records indicate that it was in fact raining, then there is no problem with an expert simply noting that the weather data seems to be consistent with the testimony of Witness A and not Witness B.

Or in another example, suppose there are five witnesses to a slip and fall in a hotel lobby. Four of them say that there was water on the floor in the lobby at the time of the fall, and one witness says there was no water. In such a case, an expert witness would be free to point out the obvious, which is that a majority of the witnesses recall water being on the floor. This statement is not an opinion as to witness credibility; it is simply noting the distribution of different accounts.

Second, a good idea for expert witnesses in testimony is to acknowledge any incompatibilities in witness accounts and condition opinions accordingly. So, using the previous slip and fall scenario with the five witnesses, if it is my opinion based on the evidence that the hotel failed to maintain safe premises, I could offer this type of conditional opinion: “The presence of water on the floor at the time of the incident is in dispute. If there was in fact water on the floor as reported by four witnesses, then it appears the hotel failed to adequately maintain safe premises for their guests.”

Note that, with the language example I used, I am not taking a side on the issue of witness credibility one way or another. I am not stating or even suggesting that anyone is “right” or “wrong” or being honest or dishonest.

Instead, I am acknowledging the fact that not everyone agrees about the presence of the water, and I am disclaiming that my opinion only stands insofar as water was actually there. Through carefully constructing statements in this way, experts can avoid a lot of headaches with accusations about bias regarding witness credibility issues.

Although expert witnesses have a fairly broad scope with respect to their expert opinions, there are also areas into which expert witnesses should generally refrain from stepping. Knowing the rules of expert witness civil procedure and staying “within the lines” fosters a long expert witness career that maintains one’s integrity and professionalism from beginning to end.

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Gary Deel

Dr. Gary Deel is a faculty member with the Dr. Wallace E. Boston School of Business. He holds an M.S. in Space Studies, an M.A. in Psychology, an M.Ed. in Higher Education Leadership, an M.A. in Criminal Justice, a J.D. in Law, and a Ph.D. in Hospitality/Business Management. Gary teaches classes in various subjects for the University, the University of Central Florida, the University of Florida, Colorado State University, and others.

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