Party not bearing the burden of proof need not present medical causation evidence to a reasonable degree of medical probability.
Kline v. Zimmer, Inc. (May 26, 2022, B302544) __ Cal.App.5th ___ [2022 WL 1679539]
Gary Kline was implanted with an artificial hip joint manufactured by Zimmer, Inc. The surgery was unsuccessful. Kline underwent further procedures and therapy for the next eight years. He then sued Zimmer on a products defect theory. At trial, the court excluded Zimmer’s proffered expert testimony regarding possible explanations of Kline’s persistent pain that were expressed to less than a reasonable medical probability. In contrast, the court allowed Kline’s expert to testify that, to a reasonable degree of medical probability, Zimmer’s defective product caused Kline’s symptoms. The jury returned a verdict for Kline, and the trial court denied Zimmer’s motion for posttrial relief. Zimmer appealed the ensuing judgment.
The Court of Appeal reversed the judgment and remanded for retrial on whether Zimmer’s defective product caused Kline’s alleged harm. The court held that Zimmer was entitled to introduce expert testimony regarding possible (albeit not probable) explanations for Kline’s symptoms to show that Kline had failed to satisfy his burden of proving that Zimmer caused Kline’s injuries. The court explained that “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” because such testimony “could cast doubt on the accuracy and reliability of a plaintiff’s expert.” When the jury is called upon to decide complex issues of medical causation it is “imperative that the party without the burden of proof be allowed to suggest alternative causes, or the uncertainty of causation, to less than a reasonable medical probability. 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.” The court found the error was necessarily prejudicial because it affected a core issue on which expert testimony was needed.