Attorneys call on expert witnesses for their in-depth knowledge of complex topics relevant to the case. The right expert can explain technical processes, summarize areas of their field, or provide clarity on specialized issues. Ideally, expert testimony helps the judge or jury understand key facts and reach better conclusions. However, an expert’s own conclusions may cross the line from sharing facts to implying or stating a legal conclusion.
Expert witnesses who stray into “legal conclusion” territory are outside their lane. Defining the applicable law is the judge’s responsibility. Judges will not tolerate expert witnesses who cross that boundary, whether or not they do so intentionally. Here, we’re discussing how to help an expert witness remain focused on the facts.
Expert Witness Testimony: How Far is Too Far?
Consider the example of Krys v. Aaron, a 2015 case before the U.S. District Court for the District of New Jersey. The case’s central question was: Did the defendants know that a hedge fund’s excess cash was intermingled with their other holdings?
The plaintiffs offered a professor of law as an expert witness. The professor clarified certain points regarding industry practices and various regulations that applied to the case. This is a reasonable expectation for any expert in a similar position.
However, the expert in Krys went further and offered two opinions. Firstly they concluded that applicable laws entitled the plaintiffs to segregation of the excess cash. Secondly, they stated that the “defendants’ ‘many’ egregious violations, ‘especially when viewed in their totality in the circumstances of this case constitute a knowing fraud, breach of fiduciary duty and trust, and conversion.”
The district court found that these opinions constituted impermissible legal conclusions. It said that the expert had “render[ed] a legal opinion concerning whether various agents of [the defendants] complied with their obligations under federal securities law.” Here, the court chose not to simply strike the expert’s report entirely. Rather, the district court attempted to clarify the line between permissible expert opinions and impermissible legal conclusions.
Understanding the Rules Governing Expert Testimony
Experts are allowed to offer testimony that “embraces an ultimate issue to be decided by the trier of fact” per Federal Rule of Evidence 704(a). This allowance creates space for an expert to complete their line of reasoning on a case. Also, it saves a judge or jury from drawing their own conclusions.
Though an expert may discuss ultimate issues, the expert may not tell the fact-finder what result to reach. The notes on FRE 704(a) provides this probate example: An expert witness can discuss whether they believe the will’s author had the mental capacity to “know the nature and extent of his property and the natural objects of his bounty and to formulate a rational scheme of distribution.” The expert cannot, however, go one step further and say whether the person “had the capacity to make a will.”
The Krys court found that, in this context, the law professor’s expert testimony was largely admissible. The one exception was where it “reache[d] the specific conclusion that any of the defendants acted in compliance with and/or in violation of applicable legal duties or segregation requirements.”
How to Help Experts Testify on an Ultimate Issue
The objection risk increases then an expert’s testimony “embraces an ultimate issue to be decided by the trier of fact.” Attorneys can help their experts avoid accusations of rendering an impermissible legal opinion in several ways.
First, help expert witnesses focus on the abstract, not the particular. The Krys court stated that while an expert “may provide an opinion on whether a party’s conduct or actions meet the underlying bases for an ultimate issue in the case,” the expert may not “merely instruct the jury on the result to reach based upon a party’s specific conduct or actions.”
For example, consider the example given in FRE 704. The ultimate issue for the jury to decide is “Did the testator have the capacity to make a will?” This is the question your expert witness must stop short of answering directly.
Reroute Expert focus
Instead, assist the expert in focusing on the elements that constitute capacity. What does it mean to “know the nature and extent of your property,” to “know the natural objects of one’s bounty,” and “to formulate a rational scheme of distribution?” What evidence indicates, generally, the meeting of each criterion?
An expert witness may even go so far as to say whether or not the evidence in this case supports each of those criteria. Generally speaking, however, experts may not take the final step: “And therefore, this testator had/lacked capacity.” That step should be left for the trier of fact.
Focus on questions like “What do we mean by this phrase?”, “What types of evidence would tend to fulfill the requirements listed here?”, and “Do we see that evidence in this case and if so, what does it look like?” With this focus, attorneys and expert witnesses can build a clear picture of applicable expert criteria. And most importantly, legal teams can achieve this without explicitly stating a legal conclusion.