When Does the Number of Experts Used By One Side Become Cumulative?

In Shallow v. Follwell, plaintiffs Heather Shallow, Michael Bishop, and Todd Bishop sued Dr. Richard Follwell, alleging the negligent wrongful death of the plaintiffs’ mother after her bowel was perforated during surgery. Plaintiffs alleged that in addition to perforating the bowel, Dr. Follwell failed to recognize and treat the injury after surgery. On appeal, plaintiffs argued, in part, Follwell’s presentation of expert witnesses was cumulative.

Dr. Follwell’s expert witnesses included:

• A general care surgeon
• A cardiologist
• A vascular surgeon
• A colorectal surgeon

Standard of Review

In Missouri, the standard of review for reversal regarding the admission or exclusive of evidence at the trial court is “a clear abuse of discretion.” When a ruling “is clearly against the logic of the circumstances then before the court and is so unreasonable and arbitrary that it shocks the sense of justice and indicates a lack of careful, deliberate consideration,” this ruling is “a clear abuse of discretion.”

Argument Against Multiple Experts

Plaintiffs argued that the testimony of the four experts was cumulative, as the testimony of each expert overlapped that of some or all of the other testifying experts. Of note, Follwell also testified on his own behalf, both as a fact witness and as an expert witness. Under Missouri Statute § 490.065, experts may testify if they have “scientific, technical or other specialized knowledge [that] will assist the trier of fact to understand the evidence or to determine a fact in issue,” where the testifying witness is qualified as an expert by any of the following:

1. Knowledge
2. Skill
3. Experience
4. Training
5. Education

Assuming they have the proper qualifications and that their knowledge will assist the trier of fact, the expert witness may offer their opinion as to the matter.

However, other rules of evidence still apply, including the rules governing relevant evidence. Evidence is relevant “if it tends to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.” However, courts must still engage in a balancing test to determine whether the relevant evidence poses the risk of unfair prejudice, cumulativeness, confusion of the issues, misleading the jury, or is an undue delay or waste of time. Where the cost of admitting otherwise relevant evidence “substantially outweighs” the benefits, the evidence should be excluded.

Plaintiffs argued that admitting four experts, along with Dr. Follwell’s testimony, is cumulative.

Cumulative Evidence Defined

Missouri has previously defined cumulative evidence as follows: when evidence “relates to a matter so fully and properly proved by other testimony as to take it out of the area of serious dispute.”

Importantly, courts do not have the discretion “to reject evidence as cumulative when it goes to the very root of the matter in controversy or relates to the main issue, the decision of which turns on the weight of the evidence.”

The Position of the Defense

The defendant argued on appeal that when defending a wrongful death action which arose from medical negligence, the “very root of the matter in controversy” is whether the defendant did, in fact, breach the standard of care or provide causation. Because Follwell maintained the testimony was critical to these issues, Follwell argued the presentation of four different witnesses on the issue was proper.

The Court’s Analysis

The court reviewed the testimony of Follwell’s experts to determine whether the witness testimony was “cumulative.” They noted each of the four experts testified about the “very root of the matter in controversy,” however, each of the experts had a different specialty, and they each added their “own parts” to the narrative. The court conceded the testimony did overlap at certain times, however, each expert testified about information related to their own specialties. When there was overlapping testimony, the court found, the testimony went to the issues of causation and the standard of care which, the court notes, are the very root of a wrongful death action in a medical negligence case.

Limitations of the Ruling

The Supreme Court noted the ruling should not be read as an open invitation to call endless witnesses, nor that testimony that goes to the very root of the controversy will always be legally relevant. In every case, the probative value of relevant evidence going to the root of the controversy must also be weighed against the risk of unfair prejudice.

An excessive number of expert witnesses can create the risk that the trier of fact will simply resolve inconsistencies in expert opinions by merely counting the number of witnesses each side calls, rather than providing due consideration to the credibility and quality of each expert’s opinion. While not the only measure, one measure of prejudicial testimony is where the testimony tends to “lead the jury to decide the case on some basis other than the established propositions of the case.”

Upholding the Trial Court’s Ruling

Because the trial court is “uniquely positioned” to evaluate the testimony and demeanor of the witnesses, the trial court is in the best position to determine whether testimony carries with it a prejudicial impact that outweighs the value of the testimony. The Supreme Court found the trial court carefully considered the plaintiffs’ objections to the cumulative nature of the evidence at the time and offered rulings as to why the court did not believe the testimony was so unfairly prejudicial that excluding the evidence was necessary. In that the court did not abuse their discretion, the judgement of the trial court must stand.

The Effect of the Ruling

Technically, this ruling only impacts the attorneys and judges practicing in the state of Missouri. However, every state, and the federal courts, all have similar Rules of Evidence that they follow. Rule 403 tends to be fairly consistent from state to state, and tends to align closely, if not identically, to the federal rule, which states:

The court may exclude relevant evidence if its probative value is substantially outweighed by a danger of one or more of the following: unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.

Because what is and what is not considered cumulative is, by and large, a judgment call, attorneys and experts would be wise to delineate their differences for the court prior to the beginning of testimony.