Exclusion of Expert Opinion Held Structural Error on Appeal Requiring Automatic Reversal

In one of the many lawsuits by hip-replacement patients against the maker of the Durom Cup, Kline v. Zimmer, Inc. (D2d8 may 26, 2022) ___ Cal.Rptr.3d ___ 2022 WL 1679539 held the trial court committed structural error when it improperly excluded Zimmer’s expert to rebut the plaintiff’s expert. This is surprising because, normally, trial court rulings on evidence are reviewed for abuse of discretion, and errors are only reversed if the appellant shows they affected the result. But the exclusion of a rebuttal expert here resulted in automatic reversal.

The plaintiff had offered expert testimony that his pain and weakness were the result of a defect in the Durom Cup. Zimmer offered its own expert to opine on alternative causes of the plaintiff’s complaints. Zimmer conceded that those alternatives were “less than a reasonable medical probability,” but still, they were plausible causes that the jury ought to consider in making its finding on causation.

Following precedent that expert causation opinions are inadmissible if expressed short of a reasonable medical probability, the trial court excluded Zimmer’s rebuttal expert. The jury returned a verdict against Zimmer of over $80,000 in economic damages and $7.6 million in noneconomic damages.

The Court of Appeal reversed.

The Trial Court Erred in Excluding Rebuttal Expert Opinion on Grounds the Opinion Was Less Than a Reasonable Medical Probability:

First, the court acknowledged that an expert opinion expressed to less than a reasonable medical probability is a ground for exclusion. “To allow a jury to consider a claim where the plaintiff's prima facie showing falls short of reasonable medical probability would be to allow the jury to find the requisite degree of certainty where science cannot: “ ‘If the experts cannot predict probability in these situations, it is difficult to see how courts can expect a jury of laymen to be able to do so.’ ” (Ortho Pharmaceutical, supra, 163 Cal.App.3d at p. 403 [quoting Parker v. Employers Mut. Liability Ins. Co. (Tex. 1969) 440 S.W.2d 43, 49].)”

But that is not a ground to exclude rebuttal opinion. The court agreed with Zimmer that “to have a defendant state affirmatively that one cause rises to the level of reasonable degree of medical probability is improper burden shifting upon the defendant.”

As the court put it: “Zimmer did not need to show that a different cause was more likely than not the cause of Kline's injuries. All that Zimmer needed to show was that Kline's evidence was insufficient to prove Kline's injuries were more likely than not caused by Zimmer. It should have been permitted to do so by offering expert opinions offered to less than a reasonable medical probability that Kline's injuries may have been attributable to other causes.”

In other words, a defendant is entitled to offer alternative theories, and it is error to require the defendant, as a threshold matter, to establish the alternative theory is more probable than not.

A few interesting comments about the role of experts and juries in deciding scientific questions:

The court made a few other epistemological observations about arriving at conclusions about the world:

• “to allow testimony from a sincere but overconfident expert, but not from an equally sincere expert harboring reasonable doubts, risks closing the courtroom door to scientific consensus (or the absence thereof).”
• “To withhold such information from the jury is to deprive it of relevant information in assessing whether the plaintiff has met its ultimate burden of persuasion.”
• Withholding valid-but-unlikely expert opinions from the jury “would improperly transfer from the jury to the court the responsibility for resolving conflicts between competing expert opinions.”
• “just because an opinion does not reach the reasonable medical probability threshold does not render it speculative…. While the trial court has discretion to determine the point at which an opinion becomes speculative, subject to the applicable provisions of the Evidence Code, that threshold is necessarily shy of the 50 percent likelihood cutoff imposed on Zimmer in this case.”

Improper Exclusion of the Only Expert Rebuttal Was Structural Error:

An evidence ruling normally is reversible only if it worked a different result. (Karlsson v. Ford Motor Co. (2006) 140 Cal.App.4th 1202, 1223.) This rule is compelled by article VI, section 13, of the California Constitution, section 353 of the Evidence Code, and section 475 of the Code of Civil Procedure.

But “structural” errors are reversible per se. “One element of a fair trial is the right to offer admissible evidence on a material issue. (Elkins v. Superior Court (2007) 41 Cal.4th 1337, 1357, superseded by statute on other grounds as stated in In re Marriage of Swain (2018) 21 Cal.App.5th 830, 840.) Therefore, improper exclusion of expert testimony can amount to structural error when it deprives a party of this right.”

Where excluded rebuttal opinion was the only rebuttal opinion, the exclusion leads to a “one-sided presentation of evidence.” Thus, the court held, “The trial court's categorical exclusion of Zimmer’s expert testimony on a central issue, which was beyond the experience of laypeople, deprived Zimmer of a fair trial and therefore constitutes structural error.”

The Upshot: This is the second reversal after a trial, which means the parties will have to try this case a third time. The trial judge, the Hon. Daniel J. Buckley, is a former personal-injury defense attorney. This suggests that, despite the care and experience devoted to this trial, trial procedure governing experts is both extraordinarily important and extraordinarily variable. To the extent expert issues can be crystallized in motions in limine, trial counsel should consider taking up a writ petition.